Ameren (AEE) 10-K risk factor changes: FY2023 vs FY2022

Certain events could prevent us from recovering our costs in a timely manner or [added: at all, or] from earning adequate returns on our investments.

Ameren [removed: Missouri’s electric and] [added: Illinois’] natural gas [removed: utility] rates established in those proceedings are [removed: primarily] based on [removed: historical] [added: estimated future] costs, revenues, and sales volumes.

Ameren [removed: Illinois’] [added: Missouri’s electric and] natural gas [added: utility] rates established in those proceedings [removed: are]

[added: are primarily] based on [removed: estimated future] [added: historical] costs, revenues, and sales volumes.

[removed: Beginning] [added: Effective for rates beginning] in 2024 through at least 2027, Ameren Illinois’ electric distribution rates will be established through an MYRP as discussed in the following risk [removed: factor, which will be based on estimated future costs and an applicable revenue requirement reconciliation, which may not allow for full recovery of actual costs due to a reconciliation cap.][added: factor.]

[removed: Effective for rates beginning] [added: Beginning] in 2024 through at least 2027, [removed: Ameren Illinois will establish] electric distribution rates [added: for Ameren Illinois are established] through an MYRP, which [removed: is] [added: are] subject to [removed: a reconciliation cap] [added: ongoing regulatory] and [removed: includes an ROE determined by the ICC applicable] [added: judicial proceedings and associated risks, and are subject] to [removed: each year of the four-year period.][added: a reconciliation cap.]

The [removed: IETL] [added: CEJA] resulted in changes to the regulatory framework applicable to Ameren Illinois’ electric distribution business by giving Ameren Illinois the option to file an MYRP with the ICC [removed: by mid-January 2023, with rates effective beginning in 2024,] or establish future rates through a traditional regulatory rate review, among other things.

An MYRP [removed: would establish] [added: establishes] rates for a four-year period, and Ameren Illinois has the option to file for an MYRP every four years.

Ameren Illinois elected to file an MYRP [removed: in January 2023] for rates effective in 2024 through [removed: 2027 with the ICC.][added: 2027.]

[removed: The MYRP also allows] [added: Under the MYRP,] Ameren Illinois [removed: to] [added: will] reconcile its actual revenue requirement, as adjusted for certain cost variations, to ICC-approved electric distribution service rates on an annual basis, subject to a reconciliation cap.

Certain variations from forecasted costs [removed: would be] [added: are] excluded from the reconciliation cap, including those associated with major storms; new business and facility relocations; changes in the timing of certain expenditures or investments into or out of the applicable calendar year; and changes in interest rates, income taxes, taxes other than income taxes, pension and other post-retirement benefits costs, and amortization of certain assets.

Ameren Illinois’ existing riders [removed: will] remain effective and electric distribution service revenues [removed: will] continue to be decoupled from sales volumes under the MYRP.

The actual revenue requirement for a particular year [removed: would incorporate] [added: incorporates] Ameren Illinois’ year-end rate base and actual capital structure for such year, provided that the [added: resulting revenue requirement does not exceed the 105% reconciliation cap and the] common equity ratio in such capital structure may not exceed that approved by the ICC in the MYRP.

In addition, the ICC [removed: will determine] [added: determines] the ROE applicable to each year of the four-year period.

[removed: Changes in economic] [added: Economic] conditions could result in the [added: annual] predetermined ROE becoming inadequate over the four-year period.

Ameren Illinois’ electric distribution [added: service] business is also subject to performance [removed: standards.][added: metrics.]

Failure to achieve the [removed: standards] [added: metrics] would result in a reduction in the company’s allowed ROE calculated under the [removed: formula ratemaking recovery mechanisms.][added: MYRP.]

[removed: The] [added: In addition, the] allowed ROE on energy-efficiency investments can be increased or decreased up to 200 basis points, depending on the achievement of annual energy savings goals.

[removed: With respect to] [added: In 2022,] the [removed: MYRP, a September 2022] ICC [added: issued an] order [removed: approved] [added: approving] total ROE incentives and penalties of 24 basis [removed: points,] [added: points under the MYRP,] allocated among [removed: the] seven performance metrics.

These performance metrics [removed: and the ROE incentives and penalties will] apply annually from 2024 through 2027 under the [removed: MYRP filed by Ameren Illinois.][added: MYRP, and the impact of any incentives and penalties will be excluded from the reconciliation cap described above.]

[removed: The QIP provides] [added: Previously, it provided] Ameren Illinois with recovery of, and a return on, qualifying natural gas infrastructure investments that [removed: are] [added: were] placed in service between regulatory rate reviews.

Infrastructure investments under the QIP [removed: earn] [added: earned] a return at the applicable WACC.

[removed: If Ameren Illinois is unable to recover investments under] [added: As a result of] the [removed: QIP or there is no other regulatory change,] [added: expiration of the QIP,] Ameren Illinois [removed: will be] [added: is] subject to increased regulatory lag on its natural gas infrastructure investments that are placed in service between regulatory rate reviews, which could adversely affect Ameren’s and Ameren Illinois’ investment plans and results of operations, financial position, and liquidity.

[removed: Effective] [added: As a result of the election to use the PISA, effective in] 2024, Ameren Missouri’s electric service business is subject to a limitation on increasing the annual revenue requirement due to the inclusion of incremental PISA deferrals in the revenue requirement.

[removed: A penalty incurred as the result of exceeding] [added: to which maintain revenue requirements under] the [removed: rate] [added: reconciliation] cap [removed: could] [added: limit would] adversely affect Ameren’s and Ameren [removed: Missouri’s] [added: Illinois’] results of operations, financial position, and liquidity.

[removed: The] [added: Pursuant to a Missouri] law [removed: extended] [added: that became effective in August 2022,] Ameren Missouri’s PISA election [added: was extended] through December 2028 and [removed: allows for] an additional extension through December 2033 [added: is allowed] if requested by Ameren Missouri and approved by the MoPSC, among other things.

[removed: The] [added: This] law [added: also] established a 2.5% annual limit on increases to the electric service revenue requirement used to set customer [removed: rates] [added: rates, compared to the revenue requirement established in the immediately preceding rate order,] due to the inclusion of incremental PISA deferrals in the revenue requirement.

The limitation will be effective for revenue requirements approved [added: by the MoPSC after January 1, 2024.]

Increased capital expenditures could cause incremental PISA deferrals to exceed the 2.5% [removed: limitation when it is effective,] [added: limitation,] and such amounts exceeding the 2.5% limitation would be excluded from recovery under future revenue requirements.

Failure to [removed: align] [added: limit] capital investments [added: to an amount which maintains PISA deferrals] under the 2.5% limitation could adversely affect Ameren’s and Ameren Missouri’s results of operations, financial position, and liquidity.

Failure to comply with these laws could result in the closing of facilities, alterations to the manner in which these facilities operate, increased operating costs, delays and increased costs of building new facilities, [removed: or] [added: and] exposure to fines and liabilities.

Our electric generation, transmission, and distribution and natural gas distribution and storage operations must comply with a variety of statutes and regulations relating to the protection of the environment and human health and [removed: safety] [added: safety,] including permitting programs implemented by federal, state, and local authorities.

Complex and lengthy processes are required to obtain and renew approvals, permits, and licenses for new, existing, or modified [added: energy-related] facilities.

Further, we are subject to risks from changing or conflicting interpretations of existing laws, [removed: modification] [added: modifications] to existing laws, new laws, [removed: and] new or modified permit [removed: terms.][added: terms, and enforcement of environmental laws and permits by federal, state, and local authorities.]

[removed: They could] [added: Additionally, individuals and non-governmental organizations may seek to enforce environmental laws against us,] allege injury from exposure to hazardous materials, allege a failure to comply with environmental laws, seek to compel remediation of environmental contamination, or seek to recover damages resulting from [removed: that] [added: purported] contamination.

As of December 31, [removed: 2022,] [added: 2023,] Ameren Missouri’s coal-fired energy centers represented [removed: 9%] [added: 8%] and [removed: 17%] [added: 16%] of Ameren’s and Ameren Missouri’s rate base, respectively.

Collectively, these regulations cover a variety of pollutants, such as SO2, particulate matter, NOx, mercury, toxic [removed: metals,] [added: metals] and acid gases, and CO2 [removed: emissions from new power plants.][added: emissions.]

Regulations implementing the Clean Water Act govern both intake and discharges of water, as well as evaluation of the ecological and biological impact of [removed: our operations] [added: those operations,] and could require modifications to water intake structures or more stringent limitations on wastewater discharges.

The management and disposal of coal ash is regulated under the Resource Conservation and Recovery Act and the CCR Rule, which require the closure of [removed: our] surface impoundments at Ameren Missouri’s coal-fired energy centers.

In January 2017, the district court issued a liability ruling against Ameren Missouri and, in September 2019, entered a remedy [removed: order.][added: order that required Ameren Missouri to install a flue gas desulfurization system at the Rush Island Energy Center and a dry sorbent injection system at the Labadie Energy Center.]

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

An MYRP includes a revenue requirement reconciliation, which may not allow for full recovery of actual costs due to a reconciliation cap.

Additionally, Ameren Illinois is subject to certain performance metrics that if not achieved would result in a reduction to the company’s allowed ROE.

The reconciliation cap also excludes costs recovered outside of base rates through riders.

In December 2023, the ICC issued an order in Ameren Illinois' MYRP proceeding, approving revenue requirements for electric distribution service for 2024, 2025, 2026, and 2027 of $1,162 million, $1,210 million, $1,242 million, and $1,255 million, respectively.

These revenue requirements were established under an alternative methodology which used Ameren Illinois’ previously approved 2022 year-end rate base since the order rejected the Grid Plan that was filed by Ameren Illinois as a part of the MYRP proceeding.

The ICC concluded that the proposed Grid Plan did not meet certain statutory requirements and directed Ameren Illinois to file a revised Grid Plan within three months.

Ameren Illinois expects to file a revised Grid Plan with the ICC in March 2024, and also expects to file a request to update the associated MYRP revenue requirements for 2024 through 2027 in the first half of 2024.

The 2022 year-end rate base will remain in effect through 2027, unless subsequently changed by the ICC in the rehearing discussed below or if approval of a revised Grid Plan results in an update of each year’s revenue requirement.

In January 2024, Ameren Illinois filed a request for rehearing of the ICC's December 2023 order.

The filing contended that the use of the 2022 year-end rate base for each year of the MYRP, until a revised Grid Plan is approved, is unlawful and not in compliance with the CEJA.

In addition, the filing requested the ICC revise the order to include an allowed ROE of at least 9.82% for each year of the MYRP and include a base level of investments to maintain grid reliability in each year of the MYRP, among other things.

In January 2024, the ICC partially denied Ameren Illinois’ rehearing request by denying Ameren Illinois’ request regarding the allowed ROE, and granting Ameren Illinois’ request to consider whether it is appropriate to use the 2022 year-end rate base for each year of the MYRP and to include a base level of investments to maintain grid reliability in each year of the MYRP.

Additionally, the scope of the rehearing will include a review of certain operations and maintenance expenses in each year of the MYRP.

In February 2024, Ameren Illinois filed its request in the rehearing proceeding, which proposed updated revenue requirements of $1,214 million, $1,300 million, $1,371 million, and $1,420 million, for 2024, 2025, 2026, and 2027, respectively.

An ICC decision in this rehearing is expected by late June 2024.

Also, in January 2024, Ameren Illinois filed an appeal of the December 2023 ICC order and the partial denial of Ameren Illinois’ request for rehearing to the Illinois Appellate Court for the Fifth Judicial District.

The court is under no deadline to address the appeal.

Ameren Illinois cannot predict the ultimate outcome of the revised Grid Plan filing, its request to update the associated MYRP revenue requirements for 2024 through 2027, the rehearing proceeding, or the appeal to the Illinois Appellate Court for the Fifth Judicial District.

Failure to limit capital expenditures and operation and maintenance expenses to amounts

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

Ameren Illinois’ QIP expired in December 2023, which will subject Ameren Illinois to increased regulatory lag with respect to certain natural gas infrastructure investments.

In addition, reconciliation hearings to determine the accuracy and prudence of natural gas capital investments recovered under the QIP are still ongoing.

The QIP expired in December 2023.

In addition, reconciliation hearings to determine the accuracy and prudence of natural gas capital investments recovered under the QIP from 2020 to 2023 are still ongoing.

In October 2023, the Illinois Attorney General’s office challenged the recovery of capital investments that were made during 2020, alleging that the ICC should disallow approximately $53 million in natural gas capital investments as improper and imprudent, providing a potential over-recovery of approximately $3 million in 2020.

In October 2023, the ICC staff filed testimony that supports the prudence and reasonableness of the capital investments made during 2020.

Ameren Illinois’ 2020 QIP rate recovery request under review by the ICC was within the rate increase limitations allowed by law.

Ameren Illinois cannot predict the ultimate outcome of this regulatory proceeding.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

Following an appeal from Ameren Missouri, in August 2021, the United States Court of Appeals for the Eighth Circuit affirmed the liability ruling and the district court’s remedy order as it related to the installation of a flue gas desulfurization system at the Rush Island Energy Center, but reversed the order as it related to the installation of a dry sorbent injection system at the Labadie Energy Center.

In its amended remedy order, the district court established an October 15, 2024 retirement date and, in the interim, authorized Ameren Missouri to operate the energy center as directed by the MISO.

The United States Department of Justice is seeking an order from the district court providing for additional mitigation relief.

Ameren Missouri could be required to implement mitigation relief measures, the costs of which could be material and which Ameren Missouri would not expect to recover.

Ameren Missouri is challenging such mitigation claims, noting that the scope of any such potential additional mitigation relief should be limited by the August 2021 court of appeals decision and offset by emission reductions resulting from the accelerated retirement of the Rush Island Energy Center.

In 2023, the MISO extended the system support resource designation through August 2024, and in September 2023, an agreement between Ameren Missouri and the MISO was approved by the FERC that results in the Rush Island Energy Center only operating during peak demand times and emergencies.

Construction activities are underway for the transmission upgrades approved by the MISO, with the majority of the upgrades expected to be completed in the fall of 2024.

Related to this matter, in November 2023, Ameren Missouri petitioned the MoPSC for a financing order to authorize the issuance of securitized utility tariff bonds to finance $519 million of costs related to the planned accelerated retirement of the Rush Island Energy Center, which includes the expected remaining unrecovered net plant balance associated with the facility.

Ameren Missouri requested to collect the amounts necessary to repay the bonds over approximately 15 years from the date of bond issuance.

In February 2024, the MoPSC staff filed a response to Ameren Missouri’s petition that stated Ameren Missouri’s decision to accelerate the retirement of the Rush Island Energy Center was prudent and largely supported Ameren Missouri’s securitization request.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

Ameren Illinois is utilizing the IEIMA performance-based formula ratemaking framework to establish annual customer rates effective through 2023.

As a result of its participation in the IEIMA performance-based formula ratemaking, Ameren Illinois’ ROE for its electric distribution service through 2023 and its electric energy-efficiency investments are directly correlated to yields on United States Treasury bonds.

Additionally, Ameren Illinois is subject to certain performance standards.

Ameren Illinois is utilizing the IEIMA performance-based formula ratemaking framework to establish annual customer rates effective through 2023 and will reconcile the related revenue requirements through an IEIMA reconciliation.

The reconciliation cap also excludes costs recovered through riders outside of base rates, such as riders for electric energy-efficiency investments, power procurement and transmission services, renewable energy credit compliance, zero emission credits, certain environmental costs, and bad debt write-offs, among others.

By law, Ameren Illinois’ electric distribution revenues are decoupled from sales volumes regardless of the process used to establish electric distribution rates, which ensures that the electric distribution revenues authorized in a regulatory rate review are not affected by changes in sales volumes.

Ameren Illinois’ electric energy-efficiency program rider, which includes a return at the applicable WACC on its program investments, is subject to performance-based formula ratemaking.

The ICC annually reviews each Ameren Illinois rate filing for reasonableness and prudency.

If the ICC were to conclude that Ameren Illinois’ costs were not prudently incurred, the ICC would disallow recovery of such costs.

The allowed ROE under the IEIMA and electric energy-efficiency formula ratemaking recovery mechanisms is based on the annual average of the monthly yields of the 30-year United States Treasury bonds plus 580 basis points.

Therefore, Ameren Illinois’ annual ROE for its electric distribution business is directly correlated to the yields on such bonds, which are outside of Ameren Illinois’ control.

A 50 basis point change in the annual average of the monthly yields of the 30-year United States Treasury bonds would result in an estimated $12 million change in Ameren’s and Ameren Illinois’ annual net income, based on Ameren Illinois’ 2023 projected year-end rate base, including electric energy-efficiency investments.

The performance standards applicable to electric distribution service under the IEIMA include improvements in service reliability to reduce both the frequency and duration of outages, a reduction in the number of estimated bills, a reduction of consumption from inactive meters, and a reduction in bad

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

debt expense.

The 2023 allowed ROE for electric distribution service is subject to the performance standards related to reduced estimated bills and bad debt expense, and may be decreased for penalties up to 10 basis points if these performance standards are not met.

In 2022, 2021, and 2020, there were no performance-related basis point adjustments that materially affected financial results.

While the ICC has approved a plan for Ameren Illinois to invest approximately $120 million per year in electric energy-efficiency programs through 2025, the ICC has the ability to reduce the amount of electric energy-efficiency savings goals in the future plan program years if there are insufficient cost-effective programs available, which could reduce the investments in electric energy-efficiency programs.

With respect to its natural gas delivery service business, unless extended, Ameren Illinois’ QIP will expire after December 2023.

Ameren Illinois’ QIP is subject to a rate impact limitation of a cumulative 4% per year since the most recent delivery service rate order, with no single year exceeding 5.5%.

If the rate impact limitation was met in a particular year, the amount of rate base causing the QIP rate to exceed the limitation would be exposed to regulatory lag until a year when that amount could be recovered under QIP or is added to rate base as a part of a regulatory rate review.

Upon issuance of a natural gas delivery service rate order, QIP rate base is transferred to base rates and the QIP is reset to zero.

Without legislative action, the QIP will expire after December 2023.

As a result of the election to use the PISA, Ameren Missouri’s electric service rates are subject to a rate cap through 2023.

Ameren Missouri’s rate cap under the PISA is effective through 2023 and limits electric service rate increases to a 2.85% compound annual growth rate in the average overall customer rate per kilowatthour, based on the electric rates that became effective in April 2017, less half of the annual savings from the TCJA that was passed on to customers as approved in a July 2018 MoPSC order.

Increased capital investments and operating costs could cause customer rates to exceed the 2.85% rate cap effective through 2023.

In addition, a decrease in off-system sales or capacity revenues or an increase in purchased power expense, all of which are included in net energy costs within the FAC, could also contribute to customer rates exceeding the rate cap.

Off-system sales are affected by generation availability, which is affected by planned and unplanned outages at Ameren Missouri’s energy centers, curtailment of generation resulting from unfavorable economic conditions, the addition of new generation sources, and retirements of Ameren Missouri’s energy centers, among other things.

If rate changes from the FAC or the RESRAM riders would cause rates to temporarily exceed the 2.85% rate cap, the overage would be deferred for future recovery in the next regulatory rate review; however, rates established in such regulatory rate review would be subject to the rate cap.

Any deferred overages approved for recovery would be recovered over a period of 20 years following approval of amounts in a regulatory rate review.

Excluding customer rates under the MEEIA rider, which are not subject to the rate cap, Ameren Missouri would incur a penalty equal to the amount of deferred overage that would cause customer rates to exceed the 2.85% rate cap until new rates are established in the next regulatory rate review.

Also, due to a change in customer behavior and certain business practices resulting from the COVID-19 pandemic, there has been a shift in sales volumes by customer class at Ameren Missouri, which began in 2020, resulting in an increase in residential sales, and a decrease in commercial and industrial sales.

While Ameren Missouri's electric sales volumes in 2022, excluding the estimated effects of weather and customer energy-efficiency programs, were comparable to the same period in 2021 and to pre-pandemic levels, long-term declines in sales volumes, along with increased capital investments and operating costs, could result in Ameren Missouri’s inability to recover amounts exceeding the rate cap.

Missouri Senate Bill 745 became effective on August 28, 2022.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

by the MoPSC after January 1, 2024, and will be based on the revenue requirement established in the immediately preceding rate order.

Additionally, private individuals may seek to enforce environmental laws against us.

That remedy order included a requirement to install a flue gas desulfurization system at the Rush Island Energy Center, which was upheld through an appeals process by the United States Court of Appeals for the Eighth Circuit in the fourth quarter of 2021.

The March 31, 2024 compliance date contained in the district court’s September 2019 remedy order remains in effect unless extended by the district court.

Discussion regarding our financial condition and results of operations for the year ended December 31, [removed: 2020,] [added: 2021,] including comparisons with the year ended December 31, [removed: 2021,] [added: 2022,] is included in Item 7 of our Form 10-K for the year ended December 31, [removed: 2021, filed with the SEC on February 23,] 2022.

In addition to presenting results of operations and earnings amounts in total, we present certain information in cents per [removed: diluted] share.

We believe this per [removed: diluted] share information helps readers to understand the impact of these factors on Ameren’s earnings per diluted share.

Our core strategy is driven by the following three pillars, which allow us to capitalize on opportunities to benefit our customers, [removed: our] [added: communities,] shareholders, and the environment:

| To capitalize on opportunities to benefit our customers, [removed: our] [added: communities,] shareholders, and the environment | | | | | | | | | | | | | | | | | | | | |

| We invest in rate-regulated energy infrastructure and seek to earn competitive returns on our investments. We seek to make prudent investments that benefit our customers. The goal of these investments is to maintain and enhance the reliability of our services, develop and deliver cleaner sources of energy, create economic development opportunities in our region, and provide customers with more options and greater control over their energy usage, among other things. By prudently investing in our businesses, we believe that we deliver superior value to both customers and shareholders. | | | | | | | | | We seek to partner with our stakeholders, including our customers, regulators, federal and state legislators, and RTOs, to enhance our regulatory frameworks and advocate for responsible energy and economic policies for the benefit of our customers and shareholders. We believe [removed: constructive] [added: enhancing our] regulatory frameworks [removed: for] [added: is important to drive] investment [removed: exist at all of] [added: in] our business [removed: segments. Accordingly, we expect to] [added: segments,] earn competitive returns on [removed: investments in our businesses] [added: those investments,] and realize timely recovery of our costs [removed: in the coming years] with the benefits accruing to both customers and shareholders. | | | | | | | | | Utilizing a continuous improvement mindset, we seek to optimize operating performance for the benefit of our customers. We remain focused on disciplined cost management and strategic capital allocation. We align our overall spending, both operating and capital, with economic conditions and with the frameworks established by our regulators. We focus on minimizing the gap between allowed and earned ROEs and allocating capital resources to business opportunities that we expect will provide the most benefit to our customers and offer the most attractive risk-adjusted return potential. | | |

| Rate Base ($ in billions)(a) | | | | | | | | | [removed: Constructive Regulatory] [added: Regulatory] Frameworks(c) | | | | | | | | | [removed: TSR 2017-2022(f)] [added: Improved Reliability(f)] | | |

| [removed: ] [added: ] | | | | | | | | | Segment | | | Regulatory Framework | | | | | | [removed: ] [added: ] | | |

| | | | Ameren Illinois Electric Distribution | | | [removed: *Formula ratemaking*] [added: *Future test year ratemaking under an MYRP(d)*] *Allowed ROE of [removed: 30-year U.S. Treasury + 5.8%*(d)] [added: 8.72%(e)*] | | | | | | | | | | | | | | |

| | | | Ameren Illinois Natural Gas | | | *Future test year ratemaking and [removed: QIP, PGA,] [added: PGA and] VBA Allowed ROE of [removed: 9.67%*] [added: 9.44%*] | | | | | | | | | | | | | | |

| | | | Ameren Missouri | | | *Historical test year ratemaking [removed: and* *PISA,] [added: and PISA,] RESRAM, FAC, MEEIA, [removed: PGA* *Allowed] [added: PGA Allowed] ROE is not [removed: specified*(e)] [added: specified*] | | | | | | | | | | | | | | |

In February [removed: 2023,] [added: 2024,] Ameren Missouri filed an update to its Smart Energy Plan with the MoPSC, which includes a five-year capital investment overview with a detailed one-year plan for [removed: 2023.][added: 2024.]

Investments under the plan are expected to total approximately [removed: $9.9] [added: $12.4] billion over the five-year period from [removed: 2023] [added: 2024] through [removed: 2027,] [added: 2028,] with expenditures largely recoverable under the [removed: PISA and the RESRAM.][added: PISA.]

See Note 2 [removed: –] [added: -] Rate and Regulatory Matters under Part II, Item 8, of this report for additional [removed: information.][added: information regarding the VBA.]

[removed: The] [added: Pursuant to a Missouri] law [removed: extended] [added: that became effective in August 2022,] Ameren Missouri’s PISA election [added: was extended] through [removed: December] 2028 and [removed: allows for] an additional extension through [removed: December] 2033 [added: is allowed] if requested by Ameren Missouri and approved by the MoPSC, among other things.

Ameren Missouri expects a decision by the MoPSC [removed: by April 2023.][added: in March 2024.]

In February [added: and April] 2023, the MoPSC issued [removed: an order] [added: orders] approving [removed: a nonunanimous stipulation and agreement regarding a] requested [removed: certificate of convenience and necessity] [added: CCNs] for the Huck Finn [removed: Solar Project.][added: and Boomtown solar projects, respectively.]

[added: -] In [removed: December 2021, Ameren Missouri filed a motion with] [added: September 2023,] the United States District Court for the Eastern District of Missouri [added: granted Ameren Missouri’s request] to modify a September 2019 remedy order issued by the district court [added: in order] to allow the retirement of the Rush Island Energy Center in advance of its previously expected useful life in lieu of installing a flue gas desulfurization system.

[removed: In September 2022, the] [added: The] Rush Island Energy Center began operating [removed: consistent with] [added: as] a system support resource [removed: agreement approved by the FERC in October] [added: on September 1,] 2022.

[added: - Pursuant to Missouri law, in November 2023,] Ameren Missouri [removed: expects to seek approval from] [added: petitioned] the MoPSC [added: for a financing order] to [removed: finance] [added: authorize] the [added: issuance of securitized utility tariff bonds to finance $519 million of] costs [removed: associated with] [added: related to] the [removed: retirement, including] [added: planned accelerated retirement of] the [added: Rush Island Energy Center, which includes the expected] remaining unrecovered net plant balance associated with the [removed: facility, through the issuance of securitized utility tariff bonds pursuant to Missouri’s securitization statute.][added: facility.]

See Note 14 – Commitments and Contingencies under Part II, Item 8, of this [removed: report] [added: report,] for additional [removed: information.][added: information on environmental matters, including the NSR and Clean Air Act litigation.]

[removed: Under] [added: - Pursuant to] the [removed: MYRP,] [added: CEJA, which was enacted in September 2021, Ameren Illinois may file an MYRP with] the ICC [removed: would approve] [added: to establish] base rates for electric distribution service to be charged to customers for each calendar year of [removed: the] [added: a] four-year period.

The following table [removed: includes] [added: presents] the [removed: forecasted] [added: approved] revenue [removed: requirement, the requested] [added: requirements,] ROE, [removed: the requested] capital structure common equity percentage, and [removed: the forecasted average] annual rate base [removed: for 2024 through 2027,] [added: in the ICC’s December 2023 order,] as [removed: reflected] [added: well as the proposed revenue requirements and annual rate base amounts] in Ameren Illinois’ [removed: MYRP:][added: February 2024 rehearing request filing:]

| Year | | | [removed: Forecasted Revenue] [added: Revenue] Requirement (in millions) | | | [removed: Requested ROE] [added: ROE] | | | [removed: Requested Capital] [added: Capital] Structure Common Equity [removed: Percentage(a)] [added: Percentage] | | | [removed: Forecasted Average Annual] [added: Annual] Rate Base (in billions) | | |

[removed: See] [added: For further information on the matters discussed above, see] Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this [removed: report for additional information.][added: report, and the Outlook section below.]

In [removed: December 2022,] [added: November 2023,] the ICC issued an order in Ameren Illinois’ annual update filing that approved [removed: a $61 million increase in Ameren Illinois’] electric [removed: distribution service] [added: customer energy-efficiency] rates [added: of $100 million] beginning in January [removed: 2023.][added: 2024, which represents an increase of $24 million from 2023 rates.]

The electric energy-efficiency program investments and the return on those investments are collected from customers through a [removed: rider and are not recovered through the electric distribution service performance-based formula ratemaking framework.][added: rider.]

[removed: Construction on the] [added: Related to these projects,] Ameren [removed: projects] [added: expects to begin substation upgrades in 2024 in advance of transmission line construction, which] is expected to begin in [removed: 2025,] [added: 2026,] with [added: forecasted] completion dates [removed: expected] near the end of this decade.

In addition, the new law imposes a 15% minimum tax on adjusted financial statement income, as defined in the law, [removed: assessed against] [added: for] corporations whose average annual adjusted financial statement income exceeds $1 billion for three consecutive preceding tax [removed: years,] [added: years] effective for tax years beginning after December 31, 2022.

See Note 12 – Income Taxes under Part II, Item 8, of this report for additional [removed: information.][added: information on the IRA and the amount of deferred income taxes recorded at December 31, 2023.]

In February [removed: 2022,] [added: 2024,] Ameren’s board of directors increased the quarterly common stock dividend to [removed: 59] [added: 67] cents per share, resulting in an annualized equivalent dividend rate of [removed: $2.36] [added: $2.68] per share.

[removed: *Earnings*][added: Earnings]

Net income attributable to Ameren common shareholders was [removed: $1,074] [added: $1,152] million, or [removed: $4.14] [added: $4.38] per diluted share, for [removed: 2022,] [added: 2023,] and [removed: $990] [added: $1,074] million, or [removed: $3.84] [added: $4.14] per diluted share, for [removed: 2021.][added: 2022.]

Net income was favorably affected in [removed: 2022,] [added: 2023,] compared with [removed: 2021,] [added: 2022,] by increased infrastructure investments across all business segments and a higher recognized ROE at Ameren Illinois Electric [removed: Distribution, increased retail electric sales volumes at Ameren Missouri, primarily resulting from colder winter and warmer summer temperatures experienced in 2022, and] [added: Distribution as well as] increased base rate revenues at Ameren Missouri pursuant to the [removed: December 2021] [added: June 2023] MoPSC electric rate order.

At December 31, [removed: 2022,] [added: 2023,] Ameren, on a consolidated basis, had available liquidity in the form of cash on hand and amounts available under the Credit Agreements of [removed: $1.5] [added: $2.1] billion.

Ameren has an ATM program under which Ameren may offer and sell from time to time common stock, which includes the ability to enter into forward [removed: sales] [added: sale] agreements, subject to market conditions and other factors.

As of December 31, [removed: 2022,] [added: 2023,] Ameren had approximately [removed: $1 billion] [added: $770 million] of common stock available for sale under the ATM program, which takes into account the forward sale agreements in effect as of December 31, [removed: 2022.][added: 2023.]

The following chart presents [removed: 2022] [added: 2023] capital expenditures by segment and the midpoint of projected cumulative capital expenditures for [removed: 2023] [added: 2024] through [removed: 2027] [added: 2028] by segment:

| [removed: 2022] [added: 2023] Capital Expenditures by Segment (Total Ameren – [removed: $3.4] [added: $3.6] billion) (in billions) | | | | | | Midpoint of [removed: 2023] [added: 2024] – [removed: 2027] [added: 2028] Projected Capital Expenditures by Segment (Total Ameren – [removed: $19.7] [added: $21.9] billion) (in billions) | | |

[removed: ][added: ]

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

| (a)Reflects year-end rate base except for Ameren Transmission, which is average rate base. Ameren Illinois Electric Distribution excludes electric energy-efficiency rate base. (b)Compound annual growth rate. (c)As of January 2024. (d)In January 2024, Ameren Illinois filed an appeal of the December 2023 ICC order in its MYRP proceeding. For more information on the MYRP proceeding, see Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report. (e)Ameren Illinois’ formula ratemaking framework related to energy-efficiency investments uses an allowed ROE of the annual average of the monthly yields of the 30-year United States Treasury bonds plus 580 basis points, subject to performance standards discussed in Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report. (f)As measured by Ameren Missouri’s and Ameren Illinois’ System Average Interruption Frequency Index. | | | | | | | | | | | | | | | | | | | | |

In June 2023, the MoPSC issued an order that resulted in an increase of $140 million to Ameren Missouri’s annual revenue requirement for electric retail service.

The approved revenue requirement was based on infrastructure investments as of December 31, 2022, and included an extension of the depreciable lives of the Sioux Energy Center’s assets from 2028 to 2030.

The order did not explicitly specify an ROE, capital structure, or rate base.

The order provides for the continued use of the FAC and trackers for pension and postretirement benefits, uncertain income tax positions, certain excess deferred income taxes, and renewable energy standard compliance costs that the MoPSC previously authorized in earlier electric rate orders, as well as the use of an electric property tax tracker.

It also includes a tracker for the utilization of production and investment tax credits or proceeds from the sale of such tax credits allowed under the IRA.

The order increased the annualized base level of net energy costs pursuant to the FAC by approximately $40 million from the base level established in the MoPSC’s December 2021 electric rate order.

The order also changed annualized depreciation, regulatory asset and liability amortization amounts, and the base level of expenses for trackers.

On an annualized basis, these changes reflect approximate increases in “Depreciation and amortization” of $90 million and “Other income, net”, of $100 million, related to non-service pension and postretirement benefit income, on Ameren’s and Ameren Missouri’s consolidated statements of income.

The new rates became effective on July 9, 2023.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

In June 2023, Ameren Missouri filed for CCNs with the MoPSC for four solar generation facilities, including the Split Rail Solar Project (300-MW facility, build-transfer agreement), the Cass County Solar Project (150-MW facility, development-transfer agreement), the Vandalia Solar Project (50-MW facility, self-build), and the Bowling Green Solar Project (50-MW facility, self-build).

In February 2024, Ameren Missouri, the MoPSC staff, and the MoOPC filed a nonunanimous stipulation and agreement requesting the MoPSC approve Ameren Missouri’s requests for CCNs for the Split Rail, Vandalia, and Bowling Green solar projects.

The stipulation and agreement also requests MoPSC approval of the CCN request for the Cass County Solar Project conditioned upon the facility supporting the Renewable Solutions Program and full subscription of the portion of the program supported by this facility, subject to certain other terms and conditions.

The remaining intervenors did not object to the agreement.

Each project is expected to support Ameren Missouri’s transition to renewable generation and, in addition, the Cass County Solar Project is expected to support Ameren Missouri’s Renewable Solutions Program.

In August 2023, the MoPSC issued an order approving a nonunanimous stipulation and agreement to extend Ameren Missouri’s MEEIA 2019 program for an additional year through 2024.

For 2024, the order approved the establishment of a portfolio of customer energy-efficiency programs and performance incentives that will provide Ameren Missouri an opportunity to earn revenues, including $12 million of performance incentive revenues if Ameren Missouri achieves certain program spending goals.

In 2024, Ameren Missouri expects to invest $76 million in energy-efficiency programs.

In January 2024, Ameren Missouri filed a proposed customer energy-efficiency plan with the MoPSC under the MEEIA for 2025 through 2027.

The proposed plan includes a portfolio of customer energy-efficiency programs, along with the continued use of the MEEIA rider, which allows Ameren Missouri to collect from, or refund to, customers any difference in actual MEEIA program costs and related lost electric margins and the amounts collected from customers.

If the plan is approved, Ameren Missouri intends to invest $123 million annually in the proposed customer energy-efficiency programs from 2025 to 2027.

In addition, Ameren Missouri requested performance incentives applicable to each plan year to earn revenues by achieving certain customer energy-efficiency savings and target spending goals.

If 100% of the goals are achieved, Ameren Missouri would earn performance incentive revenues totaling $56 million over the three-year plan.

Ameren Missouri also requested additional performance incentives applicable to each plan year totaling up to $14 million over the three-year plan, if Ameren Missouri exceeds 100% of the goals.

Ameren Missouri expects a decision by the MoPSC by October 2024 but cannot predict the ultimate outcome of this regulatory proceeding.

Ameren Missouri requested to collect the amounts necessary to repay the bonds over approximately 15 years from the date of bond issuance.

In February 2024, the MoPSC staff filed a response to Ameren Missouri’s petition that stated Ameren Missouri’s decision to accelerate the retirement of the Rush Island Energy Center was prudent and largely supported Ameren Missouri’s securitization request.

However, the MoPSC staff claimed Ameren Missouri’s prior actions that resulted in the adverse ruling in the NSR and Clean Air Act Litigation discussed in Note 14 – Commitments and Contingencies under Part II, Item 8, of this report, were imprudent and recommended that the impact of those actions on customers be considered in future rate reviews.

If Ameren Missouri is not allowed to recover Rush Island Energy Center costs through securitization or if future rate reviews result in revenue reductions based on Ameren Missouri’s prior actions that resulted in the adverse ruling in the NSR and Clean Air Act Litigation, it could have a material adverse effect on the results of operations, financial position, and liquidity of Ameren and Ameren Missouri.

Ameren Missouri expects a decision by the MoPSC by the end of June 2024, but cannot predict the ultimate outcome of this regulatory proceeding.

In December 2023, the ICC issued an order in Ameren Illinois' MYRP proceeding, approving base rates for electric distribution services for 2024 through 2027 and rejecting Ameren Illinois' Grid Plan, which was addressed as part of the MYRP proceeding.

Rate changes consistent with the order became effective in January 2024.

The ICC concluded that the proposed Grid Plan did not meet certain statutory requirements and directed Ameren Illinois to file a revised Grid Plan within three months.

Ameren Illinois expects to file a revised Grid Plan with the ICC in March 2024, and also expects to file a request to update the associated MYRP revenue requirements for 2024 through 2027 in the first half of 2024.

The December 2023 order adopted an alternative methodology to establish a rate base and revenue requirements for the years 2024 through 2027, using the 2022 year-end rate base approved by the ICC in its 2022 electric distribution service revenue requirement reconciliation adjustment order discussed below.

This rate base will remain in effect through 2027, unless subsequently changed by the ICC in the rehearing discussed below or if approval of a revised Grid Plan results in an update of each year’s revenue requirement.

In January 2024, Ameren Illinois filed a request for rehearing of the ICC's December 2023 order.

The filing contended that the use of the 2022 year-end rate base for each year of the MYRP, until a revised Grid Plan is approved, is unlawful and not in compliance with the CEJA.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

| (a)Reflects year-end rate base except for Ameren Transmission, which is average rate base. (b)Compound annual growth rate. (c)As of January 2023. (d)Allowed ROE is subject to performance standards as discussed in Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report. (e)Allowed ROE applicable to electric and natural gas delivery service. (f)Ameren management cautions that the stock price performance shown above should not be considered indicative of future stock price performance. | | | | | | | | | | | | | | | | | | | | |

In August 2022, Ameren Missouri filed a request with the MoPSC seeking approval to increase its annual revenues for electric service by $316 million.

The electric rate increase request is based on a 10.2% ROE, a capital structure composed of 51.9% common equity, a rate base of $11.6 billion, and a test year ended March 31, 2022, with certain pro-forma adjustments expected through an anticipated true-up date of December 31, 2022.

In January 2023, the MoPSC staff recommended an increase to Ameren Missouri's annual electric service revenues of $199 million based on a 9.59% ROE, a capital structure composed of 51.84% common equity, and a rate base as of June 30, 2022, of $10.5 billion.

Ameren Missouri expects the MoPSC staff will update its rate base estimate through the anticipated true-up date of December 31, 2022.

The MoPSC staff’s recommendation includes an adjustment to annual electric service revenues for estimated true-up items from June 30, 2022, to December 31, 2022, including the impacts of any investments made during that period.

The MoPSC proceeding

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

relating to the proposed electric service rate changes will take place over a period of up to 11 months, with a decision by the MoPSC expected by June 2023 and new rates effective by July 2023.

Missouri Senate Bill 745 became effective on August 28, 2022.

The law established a 2.5% annual limit on increases to the electric service revenue requirement used to set customer rates due to the inclusion of incremental PISA deferrals in the revenue requirement.

The limitation will be effective for revenue requirements approved by the MoPSC after January 1, 2024, and will be based on the revenue requirement established in the immediately preceding rate order.

The current rate limitation, which is effective through 2023, is a 2.85% cap on the compound annual growth rate in the average overall customer rate per kilowatthour, based on the electric rates that became effective in April 2017, less half of the annual savings from the TCJA that was passed on to customers as approved in a July 2018 MoPSC order.

The law also established electric and natural gas property tax trackers that allow Ameren Missouri to defer the difference between actual property taxes incurred and related taxes included in customer rates as a regulatory asset or regulatory liability, with the difference expected to be reflected in rate base in a subsequent rate order.

Upon the effective date of the law, Ameren Missouri began deferring amounts under these trackers.

In the 2022 electric service regulatory rate review discussed above, Ameren Missouri requested recovery of the amounts deferred under the electric property tax tracker.

In February 2022, Ameren Missouri, through a subsidiary, entered into a build-transfer agreement to acquire, after construction, the Boomtown Solar Project, a 150-MW solar generation facility, which is expected to be located in southeastern Illinois, support Ameren Missouri’s transition to renewable energy generation, and serve customers under the Renewable Solutions Program, if approved by the MoPSC.

In December 2022, the MoPSC staff filed a recommendation that the MoPSC should not approve Ameren Missouri’s July 2022 request for a certificate of convenience and necessity for the facility, arguing Ameren Missouri did not adequately demonstrate the facility is needed to continue providing service to customers.

In June 2022, Ameren Missouri, through a subsidiary, entered into a build-transfer agreement to acquire, after construction, the Huck Finn Solar Project, a 200-MW solar generation facility, which is expected to be located in central Missouri and support Ameren Missouri’s compliance with the state of Missouri’s requirement of achieving 15% of retail sales from renewable energy sources, of which 2% must be derived from solar energy sources.

Both acquisitions are aligned with the 2022 Change to the 2020 IRP, and are subject to certain conditions, including the issuance of certificates of convenience and necessity by the MoPSC for the Boomtown Solar Project and approval by the FERC for both acquisitions.

Depending on the timing of regulatory approvals and the impact of potential sourcing issues, the facilities could be completed as early as the fourth quarter of 2024.

The March 31, 2024 compliance date contained in the district court’s September 2019 remedy order remains in effect unless extended by the district court.

Transmission upgrade projects to mitigate reliability concerns have been approved by the MISO and are expected to be completed by spring of 2025.

The district court has the authority to determine the retirement date and operating parameters for the Rush Island Energy Center.

The district court is under no deadline to issue a ruling modifying the remedy order.

Related to this matter, in February 2022, the MoPSC issued an order directing the MoPSC staff to review Ameren Missouri’s planned accelerated retirement of the Rush Island Energy Center, including potential impacts on the reliability and cost of Ameren Missouri’s service to its customers; Ameren Missouri’s plans to mitigate the customer impacts of the accelerated retirement; and the prudence of Ameren Missouri’s actions and decisions with regard to the Rush Island Energy Center, among other things.

In April 2022, the MoPSC staff filed an initial report with the MoPSC in which the staff concluded early retirement of the Rush Island Energy Center may cause reliability concerns.

The MoPSC staff is under no deadline to complete this review.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

In January 2023, Ameren Illinois filed an MYRP with the ICC to be used in setting electric distribution service rates for 2024 through 2027.

| 2024 | | | $1,282 | | | 10.5% | | | 53.99% | | | $4.3 | | |

| 2025 | | | $1,373 | | | 10.5% | | | 53.97% | | | $4.6 | | |

| 2026 | | | $1,477 | | | 10.5% | | | 54.02% | | | $5.0 | | |

| 2027 | | | $1,556 | | | 10.5% | | | 54.03% | | | $5.3 | | |

(a)A capital structure of up to and including 50% common equity is deemed prudent and reasonable by law.

A higher equity ratio requires specific ICC approval.

Under an MYRP, the IETL permits any initial rate increase to be phased in, with at least 50% of the first annual period’s approved rate increase reflected in rates in the first annual period, with the remaining portion deferred as a regulatory asset that earns a return at the applicable WACC and is collected from customers over a period not to exceed two years beginning within one year after the second annual period’s rates are effective.

Ameren Illinois’ MYRP filing utilizes this phase-in provision and proposes to defer 50% of the requested 2024 rate increase of $175 million as a regulatory asset to be collected from customers in 2026.

An ICC decision in this proceeding is required by December 2023, with new rates effective starting in January 2024.

Our risk management policies are set by [removed: a] [added: the] risk management steering committee, which is composed of senior-level Ameren officers, with Ameren board of directors’ oversight.

- the discount rate applicable to [removed: asset retirement obligations,] [added: AROs,] goodwill, and defined pension and postretirement benefit plans.

See Note 1 – Summary of Significant Accounting Policies and Note 10 – Retirement Benefits under Part II, Item 8, of this report for additional information related to [removed: asset retirement obligations,] [added: AROs,] goodwill, and the defined pension and postretirement benefit plans.

The estimated increase in our annual interest expense and decrease in net income if interest rates were to increase by 100 basis points on variable-rate debt outstanding at December 31, [removed: 2022] [added: 2023] is immaterial.

The allowed ROE under Ameren Illinois’ [removed: IEIMA] electric [removed: distribution service and its electric] energy-efficiency investments formula ratemaking recovery mechanisms is based on the annual average of the monthly yields of the 30-year United States Treasury bonds plus 580 basis points.

[removed: Therefore, Ameren Illinois’] annual ROE for its electric [removed: distribution business] [added: energy-efficiency investments] is directly correlated to the yields on such bonds, which are outside of Ameren Illinois’ control.

See Note 7 – Derivative Financial Instruments under Part II, Item 8, of this report for information on the potential loss on counterparty exposure as of December 31, [removed: 2022.][added: 2023.]

Our physical and financial instruments [removed: are] subject to credit risk [removed: consisting] [added: primarily consist] of trade accounts receivables and executory contracts with market risk exposures.

[removed: The] [added: Credit] risk associated with trade receivables is mitigated by [removed: the large number of customers in a broad range of industry groups who make up] our [added: diversified] customer base.

At December 31, [removed: 2022,] [added: 2023,] no nonaffiliated customer represented more than 10% of our accounts receivable.

When that option is selected, Ameren Illinois produces consolidated bills for the applicable retail customers to reflect charges for electric distribution and purchased [removed: receivables.][added: receivables from the alternative retail electric suppler.]

As of December 31, [removed: 2022,] [added: 2023,] Ameren Illinois’ balance of purchased accounts receivable associated with the utility consolidated billing and purchase of receivables services was [removed: $31] [added: $42] million.

See [removed: Results of Operations in Management’s Discussion and Analysis of Financial Condition and Results of Operations] [added: Note 15 – Supplemental Information] under Part II, Item [removed: 7,] [added: 8,] of this report for more information on Ameren’s, Ameren Missouri’s, and Ameren Illinois’ accounts receivable balances that were 30 days or greater past due or that were a part of a deferred payment arrangement as of December 31, [removed: 2022.][added: 2023.]

Contributions to the plans and future costs could increase materially if we do not achieve pension and postretirement asset portfolio investment returns equal to or in excess of our [removed: 2023] [added: 2024] assumed return on plan assets of 6.75%.

As of December 31, [removed: 2022,] [added: 2023,] this fund was invested in domestic equity securities [removed: (65%)] [added: (68%)] and debt securities [removed: (34%).][added: (31%).]

Additionally, Ameren and Ameren Illinois have COLI contracts with net cash surrender values of [removed: $136] [added: $144] million and [removed: $8] [added: $7] million, respectively, as of December 31, [removed: 2022.][added: 2023.]

As of December 31, [removed: 2022,] [added: 2023,] that separate account is comprised of approximately 50% equity securities and 50% debt securities.

To the extent not recovered through [added: customer] rates, changes in the market values of these contracts are reflected in earnings.

Ameren Illinois has cost recovery mechanisms for power purchased, capacity, zero emission credit, and renewable energy credit [removed: costs and expects full recovery of such] costs.

In [removed: 2022,] [added: 2023,] Ameren Illinois procured power on behalf of its customers for 28% of its total kilowatthour sales.

Ameren Illinois purchases energy and capacity through [removed: the MISO and through] bilateral contracts resulting from IPA procurement [removed: events.][added: events, with any remaining needs procured through the MISO marketplace.]

The IPA has proposed and the ICC has approved multiple procurement events covering portions of years through [removed: 2025] [added: 2027] for capacity and energy.

Ameren Illinois has also entered into ICC-approved contracts for zero emission credits through [removed: 2026] [added: May 2027] and for renewable energy credits with various terms, including contracts with [removed: a] 20-year [removed: term] [added: terms] ending 2032, and contracts entered into beginning in 2018 through [removed: 2022] [added: 2024] with [removed: 15-year] [added: 15- to 20-year] terms.

The following table presents, as of December 31, [removed: 2022,] [added: 2023,] the percentages of the projected required supply of coal and coal transportation for Ameren Missouri’s coal-fired energy centers, nuclear fuel for Ameren Missouri’s Callaway Energy Center, natural gas for Ameren Missouri’s and Ameren Illinois’ retail distribution, and purchased power for Ameren Illinois that are price-hedged over the period [removed: 2023] [added: 2024] through [removed: 2027.][added: 2028.]

| Coal(a) | | | [removed: 91] [added: 98] | | % | | | | [removed: 84] [added: 85] | | % | | | | [removed: 40] [added: 48] | | % |

| Coal transportation(a) | | | 100 | | | | | | [removed: 97] [added: 100] | | | | | | [removed: 74] [added: 98] | | |

| Nuclear fuel | | | [removed: 97] [added: (b)] | | | | | | [removed: (b)] [added: 100] | | | | | | [removed: 96] [added: 100] | | |

| Natural gas for distribution(c) | | | [removed: 88] [added: 97] | | | | | | [removed: 42] [added: 50] | | | | | | [removed: 15] [added: 27] | | |

| Purchased power for Ameren Illinois(d) | | | [removed: 70] [added: 77] | | | | | | [removed: 35] [added: 37] | | | | | | [removed: 9] [added: 11] | | |

| Coal(a) | | | [removed: 91] [added: 98] | | % | | | | [removed: 84] [added: 85] | | % | | | | [removed: 40] [added: 48] | | % |

| Coal transportation(a) | | | 100 | | | | | | [removed: 97] [added: 100] | | | | | | [removed: 74] [added: 98] | | |

| Nuclear fuel | | | [removed: 97] [added: (b)] | | | | | | [removed: (b)] [added: 100] | | | | | | [removed: 96] [added: 100] | | |

| Natural gas for distribution(c) | | | [removed: 81] [added: 90] | | | | | | [removed: 49] [added: 57] | | | | | | [removed: 28] [added: 31] | | |

| Natural gas for distribution(c) | | | [removed: 89] [added: 98] | | % | | | | [removed: 41] [added: 49] | | % | | | | [removed: 13] [added: 26] | | % |

| Purchased power(d) | | | [removed: 70] [added: 77] | | | | | | [removed: 35] [added: 37] | | | | | | [removed: 9] [added: 11] | | |

The year [removed: 2023] [added: 2024] represents January [removed: 2023] [added: 2024] through March [removed: 2023.][added: 2024.]

The year [removed: 2024] [added: 2025] represents November [removed: 2023] [added: 2024] through March [removed: 2024.][added: 2025.]

This continues each successive year through March [removed: 2027.][added: 2028.]

Ameren Missouri has agreements with multiple suppliers to purchase low-sulfur coal through [removed: 2027] [added: 2028] to comply with environmental regulations.

Ameren Missouri is pursuing a program to qualify an alternate NRC-licensed [removed: supplier, and expects to obtain NRC approval in the near term.][added: supplier for contingency purposes.]

Therefore, Ameren Illinois’

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

Ameren Illinois has purchased approximately 15% of its June 2024 to May 2025 capacity needs bilaterally, however, this percentage beyond May 2025 will be dependent on the results of future IPA procurement events.

| | | | 2024 | | | | | | 2025 | | | | | | 2026 – 2028 | | |

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

Ameren Missouri is awaiting approval from the NRC, which is under no deadline to issue the approval.

Ameren Missouri received a planned delivery of enriched uranium from a Russian supplier in the spring of 2023.

The planned delivery concluded the nuclear fuel supply agreement with this Russian supplier with no future deliveries planned with any Russian suppliers.

See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for additional information on the solar facilities.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

Ameren Illinois expects to use the current IEIMA formula framework to establish annual customer rates effective through 2023 and reconcile the related revenue requirements.

A 50 basis point change in the annual average of the monthly yields of the 30-year United States Treasury bonds would result in an estimated $12 million change in Ameren’s and Ameren Illinois’ annual net income, based on Ameren Illinois’ 2023 projected year-end rate base, including electric energy-efficiency investments.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

Typically, Ameren Illinois purchases a total of 50% of its capacity needs bilaterally, with the remaining balance to be procured through the annual MISO capacity auction.

| | | | 2023 | | | | | | 2024 | | | | | | 2025 – 2027 | | |

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

Ameren Missouri is expecting a delivery for an immaterial amount of enriched uranium sourced from a Russian supplier.

This material is planned to be utilized in the near-term and could become subject to potential sanctions.

Ameren Missouri has established contingency plans to minimize its exposure risk to Russian-sourced fuel.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

[removed: ][added: ]

The extent of the regulatory lag varies for each of Ameren’s electric and natural gas jurisdictions, with the Ameren Transmission [removed: and Ameren Illinois Electric Distribution businesses] [added: business] experiencing the least amount of regulatory lag.

[removed: Depending on the] jurisdiction, the effects of regulatory lag are mitigated by various means, including annual revenue requirement reconciliations, the decoupling of revenues from sales volumes to ensure revenues approved in a regulatory rate review are not affected by changes in sales volumes, the recovery of certain capital investments between traditional regulatory rate reviews, the level and timing of expenditures, the use of future test years to establish customer rates, and the use of trackers and riders.

The following table summarizes the key terms of the rate orders in effect for customer billings for each of Ameren’s rate-regulated utilities as of January 1, [removed: 2023,] [added: 2024,] except as noted:

| | | | Rate Regulator | | | Effective Rate Order Issued In | | | [added: Rates Effective | | |] Allowed ROE | | | Percent of Common Equity | | | Rate Base (in billions) | | | Portion of Ameren’s [removed: 2022] [added: 2023] Operating Revenues(a) | | |

| Ameren Missouri | | | | | | | | | | | | | | | | | | | | | [added: | | |]

| Natural gas delivery service | | | MoPSC | | | December [removed: 2021(e)] [added: 2021] | | | [removed: (e)] [added: February 2022] | | | [removed: (e)] [added: (d)] | | | [added: (d) | | |] $0.3 | | | [removed: 3%] [added: 2%] | | |

| Ameren Illinois | | | | | | | | | | | | | | | | | | | | | [added: | | |]

| Electric distribution delivery [removed: service(f)] [added: service(e)] | | | ICC | | | December [removed: 2022] [added: 2023] | | | [removed: 7.85%] [added: January 2024] | | | [added: 8.72% | | |] 50.00% | | | $3.9 | | | [removed: 28%] [added: 29%] | | |

| Electric transmission [removed: service(h)] [added: service(g)] | | | FERC | | | [removed: (h)] [added: (g)] | | | [added: January 2024 | | |] 10.52% | | | [removed: 54.48%] [added: 54.90%] | | | [removed: $3.4] [added: $3.9] | | | [removed: 4%] [added: 5%] | | |

| ATXI | | | | | | | | | | | | | | | | | | | | | [added: | | |]

| Electric transmission [removed: service(h)] [added: service(g)] | | | FERC | | | [removed: (h)] [added: (g)] | | | [added: January 2024 | | |] 10.52% | | | 60.16% | | | [removed: $1.3] [added: $1.5] | | | [removed: 2%] [added: 3%] | | |

[removed: (e)This] [added: (d)This] rate order did not specify an ROE or a capital structure.

[removed: (f)Ameren Illinois electric distribution delivery service] [added: (g)Transmission] rates are updated annually and become effective each January.

The 10.52% return, which includes a [removed: 50 basis points] [added: 50-basis-point] incentive adder for participation in an RTO, is based on the FERC’s May 2020 order.

For additional information regarding [removed: this order and an August 2022 ruling by] the [removed: United States Court of Appeals for the District of Columbia Circuit related to a review of the May 2020 order,] [added: RTO cost-benefit study,] see Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report.

Ameren Missouri, Ameren Illinois, and ATXI must receive FERC approval to enter into various transactions, such as issuing short-term debt securities and conducting certain acquisitions, mergers, and [removed: consolidations involving electric utility holding companies.][added: consolidations.]

The SERC is one of six regional entities and represents all or portions of 16 central and southeastern states under authority from the NERC for the purpose of [removed: implementing and enforcing reliability standards approved by the FERC.]

The AMMO balancing authority area includes the load and most energy centers of Ameren Missouri, and had a peak demand of [removed: 7,584] [added: 7,836] MWs in [removed: 2022.][added: 2023.]

The AMIL balancing authority area includes the load of Ameren Illinois and certain natural gas-fired energy centers of Ameren Missouri, and had a peak demand of [removed: 8,510] [added: 8,859] MWs in [removed: 2022.][added: 2023.]

In July 2022, the ICC issued an order requiring Ameren Illinois to perform a cost-benefit study of continued participation in the MISO compared to participation in PJM Interconnection LLC, another [removed: RTO, and file the study by July 2023.][added: RTO.]

For additional information regarding [removed: the July 2022 ICC order,] [added: Ameren Illinois’ MYRP proceeding,] see Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report.

In the April [removed: 2022] [added: 2023] MISO capacity auction, Ameren Missouri’s generation resources exceeded its native load capacity [removed: requirements.][added: requirements for the June 2023 through May 2024 period.]

In [removed: August] 2022, the FERC issued an order approving changes to the annual MISO capacity auction.

Beginning with the April 2023 auction for the June 2023 to May 2024 planning year, auctions [removed: will] include four seasonal load forecasts and available capacity levels and [removed: will be] [added: are] designed to cover each season’s peak demand plus a target reserve margin.

The seasonal auction structure [removed: will] [added: was established to] help to address variability in resources as the MISO begins to rely more heavily on renewable generation.

The most recent integrated resource plan was filed in September [removed: 2020] [added: 2023] and [removed: changed in June 2022 to include certain modifications to] [added: includes] Ameren Missouri’s preferred [removed: approach] [added: plan] for meeting customers’ projected long-term energy needs in a [removed: cost-effective] manner [removed: while maintaining] [added: that maintains] system reliability and customer [removed: affordability.][added: affordability while transitioning to clean energy generation in an environmentally responsible manner.]

The preferred [removed: approach] [added: plan] includes, among other things, the following:

- the continued implementation of customer energy-efficiency [added: and demand response] programs; [added: and]

- [removed: expanding renewable sources by] adding 2,800 MWs of renewable generation by [removed: 2030 and a total of 4,700 MWs of renewable generation by 2040, representing investment opportunities of $7.5 billion, inclusive of] [added: 2030, which includes] the [removed: 350] [added: 900] MWs of solar generation projects discussed in Note 2 – [removed: Rates] [added: Rate] and Regulatory Matters under Part II, Item 8, of this [removed: report;][added: report, and an additional 1,900 MWs by 2036, representing investment opportunities of $5.3 billion and $4.1 billion, respectively;]

- adding 1,200 MWs of [removed: additional] [added: other] clean dispatchable generation [added: resources] by [added: 2040 and an additional 1,200 MWs by] 2043;

- the expectation that Ameren Missouri will seek and receive NRC approval for an extension of the operating license for the Callaway Energy Center beyond its current 2044 expiration [removed: date;][added: date.]

- extending the retirement date of the [removed: coal-fired] Sioux [removed: Energy Center] [added: coal-fired energy center] from [removed: 2028 to] 2030 to [added: 2032 to] ensure reliability during the transition to clean energy generation, which is subject to the approval of a change in [removed: the asset’s] depreciable [removed: life] [added: lives of the energy center’s assets] by the [removed: MoPSC in Ameren Missouri’s 2022 electric service regulatory rate review;][added: MoPSC;]

- accelerating the retirement date of the Rush Island coal-fired energy center [added: from 2025] to [removed: 2025;][added: 2024;]

- retiring [added: 1,800 MWs of] Ameren Missouri’s [removed: other] natural gas-fired energy centers [removed: in Illinois] by [removed: 2040.][added: 2040 to comply with Illinois law;]

The addition of renewable [removed: and] [added: or] natural gas-fired [removed: combined cycle] generation facilities is subject to obtaining necessary project approvals, including FERC approval and the issuance of a [removed: certificate of convenience and necessity] [added: CCN] by the MoPSC, as applicable.

In connection with the [removed: planned] accelerated retirement of the Rush Island Energy Center, Ameren Missouri [removed: expects to seek] [added: is seeking] approval from the MoPSC to finance the costs associated with the retirement, including the remaining unrecovered net plant balance associated with the facility, through the issuance of securitized utility tariff bonds pursuant to the Missouri securitization statute.

The next integrated resource plan is expected to be filed in September [removed: 2023.][added: 2026.]

[added: Steps include evaluating the potential for further diversification of Ameren Missouri’s generation portfolio through] renewable energy generation, including wind and solar generation, natural gas-fired [removed: combined cycle] generation, including the potential to switch to hydrogen fuel and/or blend hydrogen fuel with natural gas and install carbon capture technology, extending the operating license for the Callaway Energy Center, additional customer energy-efficiency and demand response programs, distributed energy resources, and energy storage.

Missouri law [removed: requires] [added: required] Ameren Missouri to offer solar rebates [added: through December 2023] and [added: currently requires Ameren Missouri to offer] net metering to certain customers that install renewable generation at their premises.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

Depending on the

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

| Electric service(b) | | | MoPSC | | | June 2023 | | | July 2023 | | | (c) | | | (c) | | | (c) | | | 49% | | |

| Natural gas delivery service(f) | | | ICC | | | November 2023 | | | November 2023 | | | 9.44% | | | 50.00% | | | $2.8 | | | 12% | | |

(c)This rate order did not specify an ROE, capital structure, or rate base.

(e)In December 2023, the ICC issued an order in Ameren Illinois' MYRP proceeding, approving base rates for electric distribution services for 2024 through 2027.

This rate order was based on forecasted recoverable costs and an ICC-determined ROE applied to Ameren Illinois’ 2022 year-end rate base approved by the 2022 electric distribution service revenue requirement reconciliation adjustment order.

The December 2023 ICC order rejected Ameren Illinois’ Grid Plan, which was addressed as part of the MYRP proceeding.

The ICC concluded that the proposed Grid Plan did not meet certain statutory requirements and directed Ameren Illinois to file a revised Grid Plan within three months.

Ameren Illinois expects to file a revised Grid Plan with the ICC in March 2024, and also expects to file a request to update the associated MYRP revenue requirements for 2024 through 2027 in the first half of 2024.

The ICC will be under no deadline to act on the revised Grid Plan when filed.

This rate base will remain in effect through 2027, unless the rehearing of the MYRP order or approval of a revised Grid Plan by the ICC results in an update of each year’s revenue requirement.

Under an MYRP, Ameren Illinois will reconcile its actual revenue requirement, as adjusted for certain cost variations, to ICC-approved electric distribution service rates on an annual basis, subject to a reconciliation cap.

The reconciliation cap limits the annual adjustment to 105% of the annual revenue requirement approved by the ICC.

(f)This rate order was based on a 2024 future test year.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

implementing and enforcing reliability standards approved by the FERC.

Local and state land use requirements can also potentially impact our planning activities.

In July 2023, Ameren Illinois filed its cost-benefit study with the ICC.

The study concluded that continued participation in the MISO was prudent and more cost-beneficial than participation in PJM Interconnection LLC.

In January 2024, the ICC staff submitted a report recommending the ICC not take any action with regard to changing Ameren Illinois’ RTO membership.

The ICC is under no obligation to issue an order related to the cost-benefit study.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

- adding an 800-MW natural gas-fired simple-cycle energy center by 2027 and an additional 1,200-MW natural gas-fired combined-cycle energy center by 2033, representing investment opportunities of $0.8 billion and $1.7 billion, respectively;

- adding 400 MWs of battery storage by 2030 and an additional 400 MWs by 2035, representing investment opportunities of $0.6 billion and $0.7 billion, respectively;

- retiring all of Ameren Missouri’s coal-fired energy centers by 2042;

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

Ameren Illinois expects to file a revised Grid Plan with the ICC in March 2024 after its initial Grid Plan for the years 2023 to 2027 was rejected by the ICC’s December 2023 order in Ameren Illinois’ MYRP proceeding.

The second solar generation facility is planned be placed in service before the end of 2025.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

If the target program spending goal is achieved for 2024, the performance incentive would result in revenues of $12 million in 2024.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

| •Be Strategic •Continuously Improve •Deliver Results | | | •Engage Respectfully •Foster Collaboration •Think Customer | | |

We also offer flexible work arrangements, such as permitting certain employees to work from alternate locations or to make adjustments to an employee’s daily work hours, among other things, complemented by our work to advance the digital enablement of our workforce, and have enhanced our facilities and workforce policies and practices to increase collaboration and productivity.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

Our efforts extend to the community through philanthropic contributions and volunteerism, including to support non-profit organizations in leading community-building efforts, providing education and support to our community and company leaders through our diversity leadership summit, providing various training programs, and organizing and promoting opportunities for employee volunteerism.

| | | | | | | | | | | | | | | | | | | | | | | | |

| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

| | | | | | | | | | | | | | | | | | | | | |

| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |

| Electric service(b) | | | MoPSC | | | December 2021(c) | | | (c) | | | (c) | | | $10.2(d) | | | 48% | | |

| Natural gas delivery service(g) | | | ICC | | | January 2021 | | | 9.67% | | | 52.00% | | | $2.1 | | | 15% | | |

(c)This rate order did not specify an ROE, but specified that Ameren Missouri’s September 30, 2021 capital structure, which was composed of 51.97% common equity, is to be used in the PISA and RESRAM.

As a result of this order, new rates became effective in February 2022.

(d)Excludes PISA and RESRAM deferrals for investments after September 30, 2021.

Deferrals after September 30, 2021, through December 31, 2022, will be included in Ameren Missouri’s requested rate base in the 2022 electric service regulatory rate review.

As a result of this order, new rates became effective in February 2022.

This rate order was based on 2021 actual costs, expected net plant additions for 2022, and the annual average of the monthly yields during 2021 of the 30-year United States Treasury bonds plus 580 basis points, which was 2.05%.

Ameren Illinois’ 2023 electric distribution delivery service revenues will be based on its 2023 actual recoverable costs, rate base, common equity percentage, and an allowed ROE, as calculated under the IEIMA’s performance-based formula ratemaking framework.

(g)This rate order was based on a 2021 future test year, and new rates became effective in January 2021.

(h)Transmission rates are updated annually and become effective each January.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

- adding 800 MWs of battery storage by 2040, representing investment opportunities of $650 million;

- adding 1,200 MWs of natural gas-fired combined cycle generation by 2031, representing an investment opportunity of $1.7 billion, with plans to switch to hydrogen fuel and/or blend hydrogen fuel with natural gas and install carbon capture technology if these technologies become commercially available at a reasonable cost;

- retiring the remaining coal-fired energy centers as they reach the end of their useful lives;

- accelerating the retirement date of the Venice natural gas-fired energy center to 2029; and

Steps include evaluating the potential for further diversification of Ameren Missouri’s generation portfolio through

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

In January 2023, Ameren Illinois filed its first multi-year integrated grid plan for the years 2023 to 2027.

The Meramec Energy Center was retired at the end of its useful life in December 2022.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

or uncertainties of supply due to potential work stoppages, delays in coal deliveries, equipment breakdowns, and other factors.

Coal suppliers in the Powder River Basin are experiencing financial hardship because of a decrease in demand resulting from increased natural gas use and renewable energy generation, and the impact of environmental regulations and concerns related to coal-fired generation.

These financial hardships have resulted in bankruptcy filings by certain coal suppliers in recent years.

As of December 31, 2022, coal inventories at the Labadie and Sioux energy centers were below targeted levels due to transportation delays in 2022.

The IPA is expected to file its next long-term renewable resources procurement plan in 2023, which, once approved by the ICC, will establish the 2023 and 2024 renewable energy credit procurement targets.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

If the target spending goals are achieved for 2023, additional revenues of $13 million would be recognized in 2023.

The MEEIA 2019 plan includes the continued use of the MEEIA rider.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

| | | | | | |

| --- | --- | --- | --- | --- | --- |

| •Safety and security •Commitment to excellence •Respect •Accountability | | | •Diversity, equity, and inclusion •Integrity •Teamwork •Stewardship | | |

| •*We Care* about our customers, our communities, and each other *•We Serve with Passion* | | | •*We Deliver* for our customers and stakeholders, today and tomorrow •*We Win* *Together* as a result of our teamwork and collaboration | | |

We also capitalized on opportunities presented by the COVID-19 pandemic and implemented work-from-home policies, advanced the digital enablement of our workforce, and enhanced our facilities and workforce policies and practices to increase collaboration and productivity.

For additional information on material legal and administrative proceedings, see [Note 2 – Rate and Regulatory [removed: Matters](#i7b96da24b4e74d7e9eae7ba802ec632b_235),] [added: Matters](#i9832300923724c57b9a236a12cb814a6_226),] [Note 9 – Callaway Energy [removed: Center](#i7b96da24b4e74d7e9eae7ba802ec632b_265),] [added: Center](#i9832300923724c57b9a236a12cb814a6_253),] and [Note 14 – Commitments and [removed: Contingencies](#i7b96da24b4e74d7e9eae7ba802ec632b_283)] [added: Contingencies](#i9832300923724c57b9a236a12cb814a6_271)] under Part II, Item 8, of this report.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

| ☒ | | | Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the fiscal year ended December 31, [removed: 2022] [added: 2023] | | |

| [removed: ] [added: ] | | | [removed: ] [added: ] | | | [removed: ] [added: ] | | |

See [added: the] definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

As of June 30, [removed: 2022,] [added: 2023,] the aggregate market value of Ameren Corporation’s common stock, $0.01 par value, (based upon the closing price of the common stock on the New York Stock Exchange on June 30, [removed: 2022)] [added: 2023)] held by nonaffiliates was [removed: $23,231,496,514.][added: $21,380,504,079.]

All of the shares of common stock of the other registrants were held by Ameren Corporation as of June 30, [removed: 2022.][added: 2023.]

The number of shares outstanding of each registrant’s classes of common stock as of January 31, [removed: 2023,] [added: 2024,] were as follows:

| Ameren Corporation | | | Common stock, $0.01 par value per share | | | [removed: 262,028,768] [added: 266,288,867] | | |

Portions of the definitive proxy statement of Ameren Corporation and portions of the definitive information statements of Union Electric Company and Ameren Illinois Company for the [removed: 2023] [added: 2024] annual meetings of shareholders are incorporated by reference into Part III of this Form 10-K.

| [GLOSSARY OF TERMS AND [removed: ABBREVIATIONS](#i7b96da24b4e74d7e9eae7ba802ec632b_10)] [added: ABBREVIATIONS](#i9832300923724c57b9a236a12cb814a6_10)] | | | | | | | | | [removed: [1](#i7b96da24b4e74d7e9eae7ba802ec632b_10)] [added: [1](#i9832300923724c57b9a236a12cb814a6_10)] | | |

| [FORWARD-LOOKING [removed: STATEMENTS](#i7b96da24b4e74d7e9eae7ba802ec632b_13)] [added: STATEMENTS](#i9832300923724c57b9a236a12cb814a6_13)] | | | | | | | | | [removed: [4](#i7b96da24b4e74d7e9eae7ba802ec632b_13)] [added: [4](#i9832300923724c57b9a236a12cb814a6_13)] | | |

| Item 1. | | | [removed: [Business](#i7b96da24b4e74d7e9eae7ba802ec632b_19)] [added: [Business](#i9832300923724c57b9a236a12cb814a6_19)] | | | | | | [removed: [6](#i7b96da24b4e74d7e9eae7ba802ec632b_19)] [added: [6](#i9832300923724c57b9a236a12cb814a6_19)] | | |

| | | | [Business [removed: Segments](#i7b96da24b4e74d7e9eae7ba802ec632b_25)] [added: Segments](#i9832300923724c57b9a236a12cb814a6_25)] | | | | | | [removed: [7](#i7b96da24b4e74d7e9eae7ba802ec632b_25)] [added: [7](#i9832300923724c57b9a236a12cb814a6_25)] | | |

| | | | [Rates and [removed: Regulation](#i7b96da24b4e74d7e9eae7ba802ec632b_28)] [added: Regulation](#i9832300923724c57b9a236a12cb814a6_28)] | | | | | | [removed: [7](#i7b96da24b4e74d7e9eae7ba802ec632b_28)] [added: [7](#i9832300923724c57b9a236a12cb814a6_28)] | | |

| | | | [Supply of Electric [removed: Power](#i7b96da24b4e74d7e9eae7ba802ec632b_34)] [added: Power](#i9832300923724c57b9a236a12cb814a6_34)] | | | | | | [removed: [10](#i7b96da24b4e74d7e9eae7ba802ec632b_34)] [added: [10](#i9832300923724c57b9a236a12cb814a6_34)] | | |

| | | | [Power [removed: Generation](#i7b96da24b4e74d7e9eae7ba802ec632b_37)] [added: Generation](#i9832300923724c57b9a236a12cb814a6_37)] | | | | | | [removed: [11](#i7b96da24b4e74d7e9eae7ba802ec632b_37)] [added: [11](#i9832300923724c57b9a236a12cb814a6_37)] | | |

| | | | [Renewable Energy and Zero Emission [removed: Standards](#i7b96da24b4e74d7e9eae7ba802ec632b_40)] [added: Standards](#i9832300923724c57b9a236a12cb814a6_40)] | | | | | | [removed: [12](#i7b96da24b4e74d7e9eae7ba802ec632b_40)] [added: [12](#i9832300923724c57b9a236a12cb814a6_40)] | | |

| | | | [Customer Energy-Efficiency [removed: Programs](#i7b96da24b4e74d7e9eae7ba802ec632b_43)] [added: Programs](#i9832300923724c57b9a236a12cb814a6_43)] | | | | | | [removed: [13](#i7b96da24b4e74d7e9eae7ba802ec632b_43)] [added: [13](#i9832300923724c57b9a236a12cb814a6_43)] | | |

| | | | [Natural Gas Supply for [removed: Distribution](#i7b96da24b4e74d7e9eae7ba802ec632b_46)] [added: Distribution](#i9832300923724c57b9a236a12cb814a6_46)] | | | | | | [removed: [14](#i7b96da24b4e74d7e9eae7ba802ec632b_46)] [added: [14](#i9832300923724c57b9a236a12cb814a6_46)] | | |

| | | | [Human Capital [removed: Management](#i7b96da24b4e74d7e9eae7ba802ec632b_49)] [added: Management](#i9832300923724c57b9a236a12cb814a6_49)] | | | | | | [removed: [14](#i7b96da24b4e74d7e9eae7ba802ec632b_49)] [added: [14](#i9832300923724c57b9a236a12cb814a6_49)] | | |

| | | | [Industry [removed: Issues](#i7b96da24b4e74d7e9eae7ba802ec632b_58)] [added: Issues](#i9832300923724c57b9a236a12cb814a6_55)] | | | | | | [removed: [16](#i7b96da24b4e74d7e9eae7ba802ec632b_58)] [added: [16](#i9832300923724c57b9a236a12cb814a6_55)] | | |

| | | | [Operating [removed: Statistics](#i7b96da24b4e74d7e9eae7ba802ec632b_61)] [added: Statistics](#i9832300923724c57b9a236a12cb814a6_58)] | | | | | | [removed: [18](#i7b96da24b4e74d7e9eae7ba802ec632b_61)] [added: [18](#i9832300923724c57b9a236a12cb814a6_58)] | | |

| | | | [Available [removed: Information](#i7b96da24b4e74d7e9eae7ba802ec632b_64)] [added: Information](#i9832300923724c57b9a236a12cb814a6_61)] | | | | | | [removed: [20](#i7b96da24b4e74d7e9eae7ba802ec632b_64)] [added: [20](#i9832300923724c57b9a236a12cb814a6_61)] | | |

| Item 1A. | | | [Risk [removed: Factors](#i7b96da24b4e74d7e9eae7ba802ec632b_67)] [added: Factors](#i9832300923724c57b9a236a12cb814a6_64)] | | | | | | [removed: [20](#i7b96da24b4e74d7e9eae7ba802ec632b_67)] [added: [20](#i9832300923724c57b9a236a12cb814a6_64)] | | |

| Item 1B. | | | [Unresolved Staff [removed: Comments](#i7b96da24b4e74d7e9eae7ba802ec632b_70)] [added: Comments](#i9832300923724c57b9a236a12cb814a6_67)] | | | | | | [removed: [31](#i7b96da24b4e74d7e9eae7ba802ec632b_70)] [added: [30](#i9832300923724c57b9a236a12cb814a6_67)] | | |

| Item 2. | | | [removed: [Properties](#i7b96da24b4e74d7e9eae7ba802ec632b_73)] [added: [Properties](#i9832300923724c57b9a236a12cb814a6_70)] | | | | | | [removed: [31](#i7b96da24b4e74d7e9eae7ba802ec632b_73)] [added: [31](#i9832300923724c57b9a236a12cb814a6_70)] | | |

| Item 3. | | | [Legal [removed: Proceedings](#i7b96da24b4e74d7e9eae7ba802ec632b_76)] [added: Proceedings](#i9832300923724c57b9a236a12cb814a6_73)] | | | | | | [removed: [33](#i7b96da24b4e74d7e9eae7ba802ec632b_76)] [added: [33](#i9832300923724c57b9a236a12cb814a6_73)] | | |

| Item 4. | | | [Mine Safety [removed: Disclosures](#i7b96da24b4e74d7e9eae7ba802ec632b_79)] [added: Disclosures](#i9832300923724c57b9a236a12cb814a6_76)] | | | | | | [removed: [34](#i7b96da24b4e74d7e9eae7ba802ec632b_79)] [added: [33](#i9832300923724c57b9a236a12cb814a6_76)] | | |

| [Information about Our Executive [removed: Officers](#i7b96da24b4e74d7e9eae7ba802ec632b_82)] [added: Officers](#i9832300923724c57b9a236a12cb814a6_79)] | | | | | | | | | [removed: [34](#i7b96da24b4e74d7e9eae7ba802ec632b_82)] [added: [34](#i9832300923724c57b9a236a12cb814a6_79)] | | |

| Item 5. | | | [Market for Registrants’ Common Equity, Related Stockholder Matters, and Issuer [removed: Purchase of] [added: Purchase](#i9832300923724c57b9a236a12cb814a6_85)[s](#i9832300923724c57b9a236a12cb814a6_85) [of] Equity [removed: Securities](#i7b96da24b4e74d7e9eae7ba802ec632b_91)] [added: Securities](#i9832300923724c57b9a236a12cb814a6_85)] | | | | | | [removed: [36](#i7b96da24b4e74d7e9eae7ba802ec632b_91)] [added: [36](#i9832300923724c57b9a236a12cb814a6_85)] | | |

| Item 6. | | | [removed: [(Reserved)](#i7b96da24b4e74d7e9eae7ba802ec632b_94)] [added: [(Reserved)](#i9832300923724c57b9a236a12cb814a6_88)] | | | | | | [removed: [37](#i7b96da24b4e74d7e9eae7ba802ec632b_94)] [added: [37](#i9832300923724c57b9a236a12cb814a6_88)] | | |

| Item 7. | | | [Management’s Discussion and Analysis of Financial Condition and Results of [removed: Operations](#i7b96da24b4e74d7e9eae7ba802ec632b_100)] [added: Operations](#i9832300923724c57b9a236a12cb814a6_94)] | | | | | | [removed: [37](#i7b96da24b4e74d7e9eae7ba802ec632b_100)] [added: [37](#i9832300923724c57b9a236a12cb814a6_94)] | | |

| | | | [Liquidity and Capital [removed: Resources](#i7b96da24b4e74d7e9eae7ba802ec632b_127)] [added: Resources](#i9832300923724c57b9a236a12cb814a6_121)] | | | | | | [removed: [57](#i7b96da24b4e74d7e9eae7ba802ec632b_127)] [added: [57](#i9832300923724c57b9a236a12cb814a6_121)] | | |

| Item 7A. | | | [Quantitative and Qualitative Disclosures About Market [removed: Risk](#i7b96da24b4e74d7e9eae7ba802ec632b_175)] [added: Risk](#i9832300923724c57b9a236a12cb814a6_166)] | | | | | | [removed: [78](#i7b96da24b4e74d7e9eae7ba802ec632b_175)] [added: [78](#i9832300923724c57b9a236a12cb814a6_166)] | | |

| Item 8. | | | [Financial Statements and Supplementary [removed: Data](#i7b96da24b4e74d7e9eae7ba802ec632b_181)] [added: Data](#i9832300923724c57b9a236a12cb814a6_172)] | | | | | | [removed: [82](#i7b96da24b4e74d7e9eae7ba802ec632b_181)] [added: [82](#i9832300923724c57b9a236a12cb814a6_172)] | | |

| | | | [Note 1. Summary of Significant Accounting [removed: Policies](#i7b96da24b4e74d7e9eae7ba802ec632b_232)] [added: Policies](#i9832300923724c57b9a236a12cb814a6_223)] | | | | | | [removed: [100](#i7b96da24b4e74d7e9eae7ba802ec632b_232)] [added: [100](#i9832300923724c57b9a236a12cb814a6_223)] | | |

| | | | [Note 2. Rate and Regulatory [removed: Matters](#i7b96da24b4e74d7e9eae7ba802ec632b_235)] [added: Matters](#i9832300923724c57b9a236a12cb814a6_226)] | | | | | | [removed: [104](#i7b96da24b4e74d7e9eae7ba802ec632b_235)] [added: [105](#i9832300923724c57b9a236a12cb814a6_226)] | | |

| | | | [Note 3. Property, Plant, and Equipment, [removed: Net](#i7b96da24b4e74d7e9eae7ba802ec632b_238)] [added: Net](#i9832300923724c57b9a236a12cb814a6_229)] | | | | | | [removed: [116](#i7b96da24b4e74d7e9eae7ba802ec632b_238)] [added: [116](#i9832300923724c57b9a236a12cb814a6_229)] | | |

| | | | [Note 4. Short-term Debt and [removed: Liquidity](#i7b96da24b4e74d7e9eae7ba802ec632b_244)] [added: Liquidity](#i9832300923724c57b9a236a12cb814a6_232)] | | | | | | [removed: [117](#i7b96da24b4e74d7e9eae7ba802ec632b_244)] [added: [117](#i9832300923724c57b9a236a12cb814a6_232)] | | |

| | | | [Note 5. Long-term Debt and Equity [removed: Financings](#i7b96da24b4e74d7e9eae7ba802ec632b_247)] [added: Financings](#i9832300923724c57b9a236a12cb814a6_235)] | | | | | | [removed: [120](#i7b96da24b4e74d7e9eae7ba802ec632b_247)] [added: [120](#i9832300923724c57b9a236a12cb814a6_235)] | | |

| | | | [Note 6. Other Income, [removed: Net](#i7b96da24b4e74d7e9eae7ba802ec632b_253)] [added: Net](#i9832300923724c57b9a236a12cb814a6_241)] | | | | | | [removed: [127](#i7b96da24b4e74d7e9eae7ba802ec632b_253)] [added: [127](#i9832300923724c57b9a236a12cb814a6_241)] | | |

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

| [PART I](#i9832300923724c57b9a236a12cb814a6_16) | | | | | | | | | | | |

| | | | [General](#i9832300923724c57b9a236a12cb814a6_22) | | | | | | [6](#i9832300923724c57b9a236a12cb814a6_22) | | |

| | | | [Transmission](#i9832300923724c57b9a236a12cb814a6_31) | | | | | | [9](#i9832300923724c57b9a236a12cb814a6_31) | | |

| Item 1C. | | | [Cybersecurity](#i9832300923724c57b9a236a12cb814a6_2738) | | | | | | [30](#i9832300923724c57b9a236a12cb814a6_2738) | | |

| [PART II](#i9832300923724c57b9a236a12cb814a6_82) | | | | | | | | | | | |

| | | | [Overview](#i9832300923724c57b9a236a12cb814a6_100) | | | | | | [38](#i9832300923724c57b9a236a12cb814a6_100) | | |

| | | | [Results of Operations](#i9832300923724c57b9a236a12cb814a6_106) | | | | | | [42](#i9832300923724c57b9a236a12cb814a6_106) | | |

| | | | [Outlook](#i9832300923724c57b9a236a12cb814a6_154) | | | | | | [67](#i9832300923724c57b9a236a12cb814a6_154) | | |

| | | | [Regulatory Matters](#i9832300923724c57b9a236a12cb814a6_157) | | | | | | [74](#i9832300923724c57b9a236a12cb814a6_157) | | |

| | | | [Accounting Matters](#i9832300923724c57b9a236a12cb814a6_160) | | | | | | [74](#i9832300923724c57b9a236a12cb814a6_160) | | |

| | | | [Ameren Corporation](#i9832300923724c57b9a236a12cb814a6_184) | | | | | | [88](#i9832300923724c57b9a236a12cb814a6_184) | | |

| | | | [Union Electric](#i9832300923724c57b9a236a12cb814a6_196) | | | | | | [92](#i9832300923724c57b9a236a12cb814a6_196) | | |

| | | | [Ameren Illinois](#i9832300923724c57b9a236a12cb814a6_208) | | | | | | [96](#i9832300923724c57b9a236a12cb814a6_208) | | |

| [PART III](#i9832300923724c57b9a236a12cb814a6_298) | | | | | | | | | | | |

| [PART IV](#i9832300923724c57b9a236a12cb814a6_316) | | | | | | | | | | | |

| [EXHIBIT INDEX](#i9832300923724c57b9a236a12cb814a6_340) | | | | | | | | | [170](#i9832300923724c57b9a236a12cb814a6_340) | | |

| [SIGNATURES](#i9832300923724c57b9a236a12cb814a6_343) | | | | | | | | | [177](#i9832300923724c57b9a236a12cb814a6_343) | | |

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

CCN – Certificate of convenience and necessity.

Formerly referred to as the Illinois Energy Transition Legislation or IETL in previous filings.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

Grid Plan – Multi-year integrated grid plan, a plan required to be filed with the ICC every four years under the CEJA, which outlines how Ameren Illinois expects to invest in electric distribution infrastructure in order to support grid modernization, clean energy, energy efficiency, and the state of Illinois’ renewable energy, equity, climate, electrification, and environmental goals over a five-year period.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

*•*pandemics or other significant global health events, and their impacts on our results of operations, financial position, and liquidity; and

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

| [PART I](#i7b96da24b4e74d7e9eae7ba802ec632b_16) | | | | | | | | | | | |

| | | | [General](#i7b96da24b4e74d7e9eae7ba802ec632b_22) | | | | | | [6](#i7b96da24b4e74d7e9eae7ba802ec632b_22) | | |

| | | | [Transmission](#i7b96da24b4e74d7e9eae7ba802ec632b_31) | | | | | | [9](#i7b96da24b4e74d7e9eae7ba802ec632b_31) | | |

| [PART II](#i7b96da24b4e74d7e9eae7ba802ec632b_88) | | | | | | | | | | | |

| | | | [Overview](#i7b96da24b4e74d7e9eae7ba802ec632b_106) | | | | | | [38](#i7b96da24b4e74d7e9eae7ba802ec632b_106) | | |

| | | | [Results of Operations](#i7b96da24b4e74d7e9eae7ba802ec632b_112) | | | | | | [42](#i7b96da24b4e74d7e9eae7ba802ec632b_112) | | |

| | | | [Outlook](#i7b96da24b4e74d7e9eae7ba802ec632b_163) | | | | | | [67](#i7b96da24b4e74d7e9eae7ba802ec632b_163) | | |

| | | | [Regulatory Matters](#i7b96da24b4e74d7e9eae7ba802ec632b_166) | | | | | | [74](#i7b96da24b4e74d7e9eae7ba802ec632b_166) | | |

| | | | [Accounting Matters](#i7b96da24b4e74d7e9eae7ba802ec632b_169) | | | | | | [74](#i7b96da24b4e74d7e9eae7ba802ec632b_169) | | |

| | | | [Ameren Corporation](#i7b96da24b4e74d7e9eae7ba802ec632b_193) | | | | | | [88](#i7b96da24b4e74d7e9eae7ba802ec632b_193) | | |

| | | | [Union Electric](#i7b96da24b4e74d7e9eae7ba802ec632b_205) | | | | | | [92](#i7b96da24b4e74d7e9eae7ba802ec632b_205) | | |

| | | | [Ameren Illinois](#i7b96da24b4e74d7e9eae7ba802ec632b_217) | | | | | | [96](#i7b96da24b4e74d7e9eae7ba802ec632b_217) | | |

| [PART III](#i7b96da24b4e74d7e9eae7ba802ec632b_310) | | | | | | | | | | | |

| [PART IV](#i7b96da24b4e74d7e9eae7ba802ec632b_328) | | | | | | | | | | | |

| [EXHIBIT INDEX](#i7b96da24b4e74d7e9eae7ba802ec632b_352) | | | | | | | | | [171](#i7b96da24b4e74d7e9eae7ba802ec632b_352) | | |

| [SIGNATURES](#i7b96da24b4e74d7e9eae7ba802ec632b_355) | | | | | | | | | [178](#i7b96da24b4e74d7e9eae7ba802ec632b_355) | | |

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

2022 Change to the 2020 IRP – A change to Ameren’s 2020 IRP filed with the MoPSC in June 2022 reflecting certain modifications to Ameren Missouri’s preferred approach for meeting its customers’ projected long-term energy needs in a cost-effective manner while maintaining system reliability and achieving a targeted goal of net-zero carbon emissions by 2045.

COVID-19 pandemic – The global pandemic resulting from the outbreak of the 2019 novel coronavirus, which causes coronavirus disease 2019 (COVID-19).

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

Missouri Environmental Authority – Environmental Improvement and Energy Resources Authority of the state of Missouri, a governmental body authorized to finance environmental projects by issuing tax-exempt bonds and notes.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

In January 2023, Ameren Illinois filed an MYRP with the ICC for rates effective beginning in 2024.

The MoPSC’s March 2020 electric rate order changed the FAC to include certain fuel additives and ash disposal costs and revenues as of April 2020.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

rates or any other recovery mechanism by adjusting customer rates on an annual basis without a traditional regulatory rate review, subject to MoPSC prudence reviews.

This rate-adjustment mechanism became effective on February 28, 2022, replacing a rate-adjustment mechanism that had decoupled natural gas revenues from actual sales.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

Illinois’ natural gas regulatory rate review filed in January 2023 with the ICC, and the August 2022 United States Court of Appeals for the District of Columbia Circuit ruling that vacated FERC’s MISO ROE-determining orders and remanded the proceedings to the FERC;

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

*•*the length and severity of the COVID-19 pandemic, and its impacts on our results of operations, financial position, and liquidity; and

The Ameren Companies have identified cybersecurity as an enterprise risk, which is managed through Ameren's integrated enterprise risk management program.

The program is designed to continuously assess risk and evaluate the likelihood and probability of impact in order to determine the appropriate risk tolerance and risk management strategies that inform our cybersecurity policies, investments, practices, controls, and countermeasures.

The program is a comprehensive, consistently applied management framework that is designed to ensure all forms of material risk and opportunity are identified, reported and managed in an effective manner overseen by the risk management steering

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

committee.

The risk management steering committee, which is composed of senior-level Ameren officers, with Ameren board of directors’ oversight, oversees Ameren's enterprise risk management processes, which include the identification, assessment, mitigation, and monitoring of risks including strategic, operational, and cybersecurity risks.

Ameren's board of directors maintains a standing committee, the Cybersecurity and Digital Technology Committee, that is dedicated to the oversight of Ameren's cybersecurity and digital technology risks.

The committee has primary responsibility for oversight of cybersecurity and digital technology risk management, including the programs, policies, practices, controls and safeguards for digital technology, information security, prevention and detection of cybersecurity incidents and information or data breaches, and cybersecurity and digital technology matters as they relate to crisis preparedness, incident response plans, and disaster recovery and business continuity capabilities.

The committee receives regular updates from the Chief Customer and Technology Officer, the Chief Information Officer, the Chief Information Security Officer, and other members of senior management regarding Ameren’s cybersecurity program and key initiatives.

The Cybersecurity and Digital Technology Committee regularly reports on its activities to Ameren’s board of directors, including reviewing and advising Ameren’s board of directors of any developments it believes should be considered.

Ameren's cybersecurity program and team are led by the Chief Information Security Officer, who possesses 25 years of critical infrastructure experience both managing and protecting information systems in concert with extensive cybersecurity operations and leadership roles.

The Chief Information Security Officer regularly engages with senior-level Ameren officers, reports to the risk management steering committee, and has recurring meetings with the Cybersecurity and Digital Technology Committee as part of ongoing risk management and oversight of the cybersecurity program.

Ameren’s board of directors is also regularly updated on its cybersecurity program.

In addition, the board of directors participate in periodic cybersecurity drills to prepare for potential crisis scenarios.

To manage against existing conduct and new cybersecurity threats, we maintain enterprise-wide cybersecurity, crisis management, and information security policies and regular training and tests that reinforce the acceptable use of Ameren's information assets, protection of customer and employee data, and the role each employee plays in protecting Ameren against cybersecurity threats.

Incident response plans and procedures are tested through recurring companywide cybersecurity exercises to promote readiness across the organization.

The procedures are also designed to escalate incidents to appropriate members of management to guide the detection, response, and recovery from a material cybersecurity incident.

To address cybersecurity threats, cybersecurity intelligence, as well as responding to cyber-related incidents, we work closely with law enforcement, cybersecurity consulting firms, and industry associations to enhance information sharing and guard against cybersecurity attacks.

We measure our cybersecurity effectiveness through formal cybersecurity scorecards and metrics reported to senior-level Ameren officers, the risk management steering committee, and the Cybersecurity and Digital Technology Committee.

These metrics include but are not limited to measures around the effectiveness of our cybersecurity controls, our ability to manage cybersecurity events and incidents, cybersecurity incident response exercises, and results of our recurring internal assessments, external assessments, and audits that Ameren regularly undergoes.

Ameren regularly engages external cybersecurity experts to assist with evaluating our cybersecurity program.

These engagements provide insights into control performance, prioritized recommendations for enhancements to our cybersecurity strategy, and an overview of the cybersecurity threat landscape that collectively inform our investments and technical controls to protect Ameren's most critical assets.

The results of these engagements are reviewed with senior-level Ameren officers and the Cybersecurity and Digital Technology Committee.

Ameren also deploys a third-party cybersecurity risk management program, which extends the governance elements described above to our third-party providers and suppliers.

The supply chain and third-party risks introduced to Ameren are evaluated prior to the commencement of any new engagement or relationship, monitored closely throughout the lifecycle of the supplier and managed through privacy and cybersecurity provisions within the respective commercial contracts.

Procedures have been established to address supplier incidents as well as supplier off-boarding at the expiration of the relationship.

We are not aware of any cybersecurity events that have materially affected or are reasonably likely to materially affect Ameren, including our business strategy, results of operations, financial position, or liquidity.

The following table shows the anticipated capability of our energy centers at the time of the expected [removed: 2023] [added: 2024] peak summer electrical demand for all energy centers owned as of December 31, [removed: 2022:][added: 2023:]

| Nuclear | | | [removed: Callaway(f)] [added: Callaway(e)] | | | Callaway County, Missouri | | | 1,194,000 | | |

| Hydroelectric | | | [removed: Osage(f)] [added: Osage(e)] | | | Lakeside, Missouri | | | 235,000 | | |

| Pumped-storage | | | Taum [removed: Sauk(f)] [added: Sauk(e)] | | | Reynolds County, Missouri | | | 440,000 | | |

| Natural gas (CTs) | | | [removed: Audrain(g)] [added: Audrain] | | | Audrain County, Missouri | | | 608,000 | | |

| | | | [removed: Venice(h)] [added: Venice(f)] | | | Venice, Illinois | | | [removed: 489,000] [added: 487,000] | | |

| | | | Goose [removed: Creek(h)] [added: Creek(f)] | | | Piatt County, Illinois | | | 438,000 | | |

| | | | [removed: Pinckneyville(h)] [added: Pinckneyville(f)] | | | Pinckneyville, Illinois | | | 316,000 | | |

| | | | Raccoon [removed: Creek(h)] [added: Creek(f)] | | | Clay County, Illinois | | | 304,000 | | |

| | | | [removed: Kinmundy(h)] [added: Kinmundy(f)] | | | Kinmundy, Illinois | | | 210,000 | | |

| | | | Peno [removed: Creek(g)] [added: Creek] | | | Bowling Green, Missouri | | | 172,000 | | |

| Total natural gas | | | | | | | | | [removed: 2,537,000] [added: 2,535,000] | | |

| Oil (CTs) | | | [removed: Fairgrounds(e)] [added: Fairgrounds(g)] | | | Jefferson City, Missouri | | | 55,000 | | |

| | | | [removed: Mexico(e)] [added: Mexico(g)] | | | Mexico, Missouri | | | 54,000 | | |

| | | | [removed: Moberly(e)] [added: Moberly(g)] | | | Moberly, Missouri | | | 54,000 | | |

| | | | [removed: Moreau(e)] [added: Moreau(g)] | | | Jefferson City, Missouri | | | 54,000 | | |

| Total solar | | | | | | | | | [removed: 14,100] [added: 15,300] | | |

| Total Ameren Missouri | | | | | | | | | [removed: 10,014,900] [added: 10,014,100] | | |

For additional information, see [added: NSR and Clean Air Act Litigation in] Note 14 – Commitments and Contingencies under Part II, Item 8, of this report.

(d)As noted in the [removed: 2022 Change to the 2020] [added: 2023] IRP, Ameren Missouri [removed: has requested] [added: plans] to extend the retirement date of the Sioux Energy Center from [removed: 2028] [added: 2030] to [removed: 2030,] [added: 2032,] which is subject to the approval of a change in [removed: the asset’s] depreciable [removed: life] [added: lives of the energy center’s assets] by the [removed: MoPSC in Ameren Missouri’s 2022 electric service regulatory rate review.][added: MoPSC.]

[removed: (e)The] [added: (g)The] Fairgrounds, Mexico, Moberly, and Moreau energy centers are scheduled to be retired by [removed: 2026] [added: the end of 2029] as noted in the [removed: 2020] [added: 2023] IRP.

[removed: (f)The] [added: (e)The] operating licenses for the Callaway, Osage, and Taum Sauk energy centers expire in 2044, 2047, and 2044, respectively.

[removed: (h)The] [added: (f)The] Venice Energy Center is scheduled to retire by [added: the end of] 2029 and the Goose Creek, Pinckneyville, Raccoon Creek, and Kinmundy energy centers are scheduled to retire by [removed: 2040] [added: the end of 2039] as noted in the [removed: 2022 Change to the 2020] [added: 2023] IRP.

The following table presents in-service electric and natural gas utility-related properties for Ameren Missouri and Ameren Illinois as of December 31, [removed: 2022:][added: 2023:]

| Circuit miles of electric transmission lines(a) | | | [removed: 3,126] [added: 3,140] | | | | | | [removed: 4,716] [added: 4,761] | | |

| Circuit miles of electric distribution lines | | | [removed: 33,846] [added: 33,927] | | | | | | [removed: 45,972] [added: 45,984] | | |

| Miles of natural gas transmission and distribution mains | | | [removed: 3,509] [added: 3,532] | | | | | | [removed: 18,680] [added: 18,713] | | |

(a)ATXI owns [removed: 545] [added: 561] circuit miles of electric transmission lines not reflected in this table.

The exceptions as of [removed: January] [added: December] 31, 2023 are as follows:

That property includes a portion of Ameren Missouri’s Osage Energy Center reservoir; certain facilities at Ameren Missouri’s Sioux Energy Center; most of Ameren Missouri’s High Prairie Renewable and Atchison Renewable energy centers; Ameren Missouri’s [removed: Maryland Heights,] [added: BJC, Cape Girardeau,] Lambert, and [removed: BJC] [added: Maryland Heights] energy centers; certain substations; and most transmission and distribution lines and natural gas mains.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

| | | | Other Solar(h) | | | Various | | | 1,400 | | |

| Total Ameren | | | | | | | | | 10,016,600 | | |

(c)The Rush Island Energy Center is scheduled to retire by October 15, 2024 per the remedy order of the United States District Court for the Eastern District of Missouri.

(h)Includes five solar energy centers that each have a nameplate capacity of 500 kilowatts or less.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

| | | | South St. Louis | | | St. Louis, Missouri | | | 200 | | |

| Total Ameren | | | | | | | | | 10,017,400 | | |

(c)The Rush Island Energy Center is scheduled to retire by 2025 as noted in the 2022 Change to the 2020 IRP.

However, changes to the retirement date are subject to a final judgment to be issued by the United States District Court for the Eastern District of Missouri regarding a September 2019 remedy order.

See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for additional information on Ameren Missouri’s request to extend the retirement date of the Sioux Energy Center.

(g)There were economic development arrangements applicable to these CTs, as discussed below.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

Ameren Missouri conveyed most of its Peno Creek CT Energy Center to the city of Bowling Green, Missouri through December 2022.

Ameren Missouri had rights and obligations as the operator of the energy center under a long-term agreement with the city of Bowling Green.

Under the terms of this agreement, Ameren Missouri was responsible for all operation and maintenance at the energy center.

Ownership of the energy center transferred to Ameren Missouri in December 2022, at which time the property, plant, and equipment became subject to the lien of the Ameren Missouri mortgage bond indenture.

Ameren Missouri operates a CT energy center located in Audrain County, Missouri.

Ameren Missouri had rights and obligations as the operator of the energy center under a long-term agreement with Audrain County.

Under the terms of this agreement, Ameren Missouri was responsible for all operation and maintenance at the energy center.

While the agreement was scheduled to expire in December 2023, Ameren Missouri and Audrain County mutually agreed to terminate the agreement in January 2023.

Ownership of the energy center was transferred to Ameren Missouri in January 2023, at which time the property, plant, and equipment became subject to the lien of the Ameren Missouri mortgage bond indenture.

See Note 5 – Long-term Debt and Equity Financings under Part II, Item 8, of this report for additional information for both agreements associated with the Peno Creek CT and Audrain County CT energy centers.

The executive officers of the Ameren Companies, including major subsidiaries, are listed below, along with their ages as of December 31, [removed: 2022,] [added: 2023,] all their positions and offices held with the Ameren Companies as of February [removed: 21, 2023,] [added: 29, 2024,] and their tenures as officers, and their titles for at least the last five years.

| [removed: Warner L. Baxter] [added: Martin J. Lyons, Jr.] | | | [removed: 61] [added: 57] | | | [added: Chairman, President, and Chief] Executive [removed: Chairman;] [added: Officer;] Ameren | | | January [removed: 2022] [added: 2022(a)] – Present | | |

[removed: | | | | | | | Chairman, President,] [added: (a)Elected President] and Chief Executive [removed: Officer;] [added: Officer of] Ameren [removed: | | | 2014(a) –] [added: in] January [removed: 2022 | | |][added: 2022, and Chairman of Ameren in November 2023.]

| Michael L. Moehn | | | [removed: 53] [added: 54] | | | [added: Senior] Executive Vice President and Chief Financial Officer; Ameren | | | [removed: December 2019] [added: March 2023] – Present | | |

| [removed: Chonda J. Nwamu] | | | [removed: 51] | | | Senior Vice President, General Counsel, and Secretary; Ameren | | | August 2019 – [removed: Present] [added: February 2023] | | |

| Theresa A. Shaw | | | [removed: 50] [added: 51] | | | Senior Vice President, Finance, and Chief Accounting Officer; Ameren | | | August 2021 – Present | | |

| [removed: Bhavani Amirthalingam] | | | [removed: 47] | | | Senior Vice President and Chief Digital Information Officer; Ameren Services | | | March [removed: 2018(a)] [added: 2018] – [removed: Present] [added: February 2023] | | |

| Mark C. Birk | | | [removed: 58] [added: 59] | | | Chairman and President; Ameren Missouri | | | January 2022 – Present | | |

| Fadi M. Diya | | | [removed: 60] [added: 61] | | | Senior Vice President and Chief Nuclear Officer; Ameren Missouri | | | January 2014 – Present | | |

| [removed: Mark C. Lindgren] | | | [removed: 55] | | | Senior Vice President, Corporate Communications, and Chief Human Resources Officer; Ameren Services | | | September 2015 – [removed: Present] [added: February 2023] | | |

| Gwendolyn G. Mizell | | | [removed: 61] [added: 62] | | | [added: Senior] Vice [removed: President,] [added: President and] Chief Sustainability, Diversity, & Philanthropy Officer; Ameren Services | | | March [removed: 2022] [added: 2023] – Present | | |

| Shawn E. Schukar | | | [removed: 61] [added: 62] | | | Chairman and President; ATXI | | | May 2017 – Present | | |

| Leonard P. Singh | | | [removed: 53] [added: 54] | | | Chairman and President; Ameren Illinois | | | August [removed: 2022(b)] [added: 2022(a)] – Present | | |

[removed: (b)Leonard] [added: (a)Leonard] P.

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

| | | | | | | Executive Vice President and Chief Financial Officer; Ameren | | | December 2019 – February 2023 | | |

| Chonda J. Nwamu | | | 52 | | | Executive Vice President, General Counsel, and Secretary; Ameren | | | March 2023 – Present | | |

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

| Bhavani Amirthalingam | | | 48 | | | Executive Vice President and Chief Customer and Technology Officer; Ameren Services | | | March 2023 – Present | | |

| Mark C. Lindgren | | | 56 | | | Executive Vice President, Corporate Communications, and Chief Human Resources Officer; Ameren Services | | | March 2023 – Present | | |

| | | | | | | Vice President, Chief Sustainability, Diversity, & Philanthropy Officer; Ameren Services | | | March 2022 – February 2023 | | |

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

| Martin J. Lyons, Jr. | | | 56 | | | President and Chief Executive Officer; Ameren | | | January 2022 – Present | | |

| | | | | | | Vice President and Deputy General Counsel; Ameren Services | | | September 2016 – January 2019 | | |

| | | | | | | Vice President, Internal Audit; Ameren | | | June 2014 – July 2018 | | |

(a)Elected President of Ameren in February 2014, Chief Executive Officer of Ameren in April 2014, and Chairman of Ameren in July 2014.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

| | | | | | | Director, Diversity, Equity and Inclusion; Ameren Services | | | October 2015 – March 2018 | | |

(a)Bhavani Amirthalingam served as the Chief Information Officer and Vice President North America for Schneider Electric SE from January 2015 to March 2018.

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

Ameren common shareholders of record totaled [removed: 37,798] [added: 35,157] on January 31, [removed: 2023.][added: 2024.]

Ameren Corporation, Ameren Missouri, and Ameren Illinois did not purchase any equity securities reportable under Item 703 of Regulation S-K during the period from October 1, [removed: 2022,] [added: 2023,] to December 31, [removed: 2022.][added: 2023.]

The following graph shows Ameren’s cumulative TSR during the five years ended December 31, [removed: 2022.][added: 2023.]

The comparison assumes that $100 was invested on December 31, [removed: 2017,] [added: 2018,] in Ameren common stock and in each of the indices shown and that all of the dividends were reinvested.

[removed: ][added: ]

| December 31, | | | [removed: 2017] [added: 2018] | | | | | | [removed: 2018] [added: 2019] | | | | | | [removed: 2019] [added: 2020] | | | | | | [removed: 2020] [added: 2021] | | | | | | [removed: 2021] [added: 2022] | | | | | | [removed: 2022] [added: 2023] | | |

[Table](#i9832300923724c57b9a236a12cb814a6_7) [of Conten](#i9832300923724c57b9a236a12cb814a6_7)[t](#i9832300923724c57b9a236a12cb814a6_7)[s](#i9832300923724c57b9a236a12cb814a6_7)

| Ameren (AEE) | | | $ | 100.00 | | | | | $ | 120.82 | | | | | $ | 125.98 | | | | | $ | 147.51 | | | | | $ | 151.26 | | | | | $ | 126.94 | |

| S&P 500 Index | | | 100.00 | | | | | | 131.47 | | | | | | 155.65 | | | | | | 200.29 | | | | | | 163.98 | | | | | | 207.04 | | |

| S&P 500 Utility Index | | | 100.00 | | | | | | 126.35 | | | | | | 127.01 | | | | | | 149.46 | | | | | | 151.79 | | | | | | 141.05 | | |

| Philadelphia Utility Index | | | 100.00 | | | | | | 126.82 | | | | | | 130.27 | | | | | | 154.03 | | | | | | 155.03 | | | | | | 140.83 | | |

[Table](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [of](#i7b96da24b4e74d7e9eae7ba802ec632b_7) [Contents](#i7b96da24b4e74d7e9eae7ba802ec632b_7)

| Ameren (AEE) | | | $ | 100.00 | | | | | $ | 113.98 | | | | | $ | 137.71 | | | | | $ | 143.59 | | | | | $ | 168.13 | | | | | $ | 172.40 | |

| S&P 500 Index | | | 100.00 | | | | | | 95.61 | | | | | | 125.70 | | | | | | 148.81 | | | | | | 191.48 | | | | | | 156.77 | | |

| S&P 500 Utility Index | | | 100.00 | | | | | | 104.11 | | | | | | 131.54 | | | | | | 132.23 | | | | | | 155.60 | | | | | | 158.03 | | |

| Philadelphia Utility Index | | | 100.00 | | | | | | 103.52 | | | | | | 131.28 | | | | | | 134.85 | | | | | | 159.45 | | | | | | 160.49 | | |

We have audited the accompanying consolidated balance sheet of Ameren Corporation and its subsidiaries (the “Company”) as of December 31, [removed: 2022] [added: 2023] and [removed: 2021,] [added: 2022,] and the related consolidated statements of income and comprehensive income, of shareholders’ equity and of cash flows for each of the three years in the period ended December 31, [removed: 2022,] [added: 2023,] including the related notes and financial statement schedules listed in the index appearing under Item 15(a)(2) (collectively referred to as the “consolidated financial statements”).

We also have audited the Company’s internal control over financial reporting as of December 31, [removed: 2022,] [added: 2023,] based on criteria established in *Internal Control - Integrated Framework* (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO).

In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of the Company as of December 31, [removed: 2022] [added: 2023] and [removed: 2021,] [added: 2022,] and the results of its operations and its cash flows for each of the three years in the period ended December 31, [removed: 2022] [added: 2023] in conformity with accounting principles generally accepted in the United States of America.

Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, [removed: 2022,] [added: 2023,] based on criteria established in *Internal Control - Integrated Framework* (2013) issued by the COSO.

As of December 31, [removed: 2022,] [added: 2023,] there were approximately [removed: $1.8] [added: $2.2] billion of regulatory assets and approximately [removed: $5.4] [added: $5.6] billion of regulatory liabilities.

We have audited the accompanying consolidated balance sheet of Union Electric Company and its subsidiaries (the “Company”) as of December 31, [removed: 2022] [added: 2023] and [removed: 2021,] [added: 2022,] and the related consolidated statements of income, of shareholders’ equity and of cash flows for each of the three years in the period ended December 31, [removed: 2022,] [added: 2023,] including the related notes and financial statement schedule listed in the index appearing under Item 15(a)(2) (collectively referred to as the “consolidated financial statements”).

In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company as of December 31, [removed: 2022] [added: 2023] and [removed: 2021,] [added: 2022,] and the results of its operations and its cash flows for each of the three years in the period ended December 31, [removed: 2022] [added: 2023] in conformity with accounting principles generally accepted in the United States of America.

As of December 31, [removed: 2022,] [added: 2023,] there were approximately [removed: $0.8] [added: $0.9] billion of regulatory assets and approximately [removed: $2.9] [added: $3.0] billion of regulatory liabilities.

The principal considerations for our determination that performing procedures relating to accounting for the effects of regulation is a critical audit matter are the significant judgment by management when accounting for (i) new or existing regulatory assets or liabilities that were [removed: impacted by updates in regulatory commission orders, legislation, historical experience, or management’s discussions with legal counsel, and (ii) the probability of recovery of regulatory assets and refund of regulatory liabilities recorded before approval has been received from the]

[added: impacted by updates in regulatory commission orders, legislation, historical experience, or management’s discussions with legal counsel, (ii) the probability of recovery of regulatory assets and refund of regulatory liabilities recorded before approval has been received from the] regulator, [added: and (iii) regulatory mechanisms meeting the alternative revenue program criteria,] which in turn led to a high degree of auditor judgment, subjectivity, and [removed: audit] effort when performing audit procedures and evaluating audit evidence obtained related to management’s application of regulatory [removed: accounting and] [added: accounting,] assessment of probability of recovery of regulatory assets and refund of regulatory [removed: liabilities.][added: liabilities, and expected timing of collection within 24 months of the end of the annual period in which mechanisms are recognized.]

These procedures included testing the effectiveness of controls relating to management’s implementation and application of new or existing regulatory assets or liabilities, including controls related to evaluating the probability of recovery of regulatory assets and refund of regulatory [removed: liabilities.][added: liabilities, and alternative revenue programs.]

These procedures also included, among others, (i) testing calculations of new and existing regulatory assets or liabilities by comparison to provisions and formulas outlined in regulatory commission [removed: orders, and] [added: orders or legislation,] (ii) evaluating management’s assessment of the probability of recovery of regulatory assets and refund of regulatory [removed: liabilities.][added: liabilities, and (iii) evaluating management’s assessment of regulatory mechanisms meeting the alternative revenue program criteria and the expected timing of collection within 24 months of the end of the annual period in which mechanisms are recognized.]

We have audited the accompanying balance sheet of Ameren Illinois Company (the “Company”) as of December 31, [removed: 2022] [added: 2023] and [removed: 2021,] [added: 2022,] and the related statements of income, of shareholders’ equity and of cash flows for each of the three years in the period ended December 31, [removed: 2022,] [added: 2023,] including the related notes and financial statement schedule listed in the index appearing under Item 15(a)(2) (collectively referred to as the “financial statements”).

In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, [removed: 2022] [added: 2023] and [removed: 2021,] [added: 2022,] and the results of its operations and its cash flows for each of the three years in the period ended December 31, [removed: 2022] [added: 2023] in conformity with accounting principles generally accepted in the United States of America.

As of December 31, [removed: 2022,] [added: 2023,] there were approximately [removed: $0.9] [added: $1.3] billion of regulatory assets and approximately [removed: $2.4] [added: $2.5] billion of regulatory liabilities.

| | | | [removed: 2022] [added: 2023] | | | | | | [removed: 2021] [added: 2022] | | | | | | [removed: 2020] [added: 2021] | | |

| Electric | | | $ | [removed: 6,581] [added: 6,439] | | | | | $ | [removed: 5,297] [added: 6,581] | | | | | $ | [removed: 4,911] [added: 5,297] | |

| Natural gas | | | [removed: 1,376] [added: 1,061] | | | | | | [removed: 1,097] [added: 1,376] | | | | | | [removed: 883] [added: 1,097] | | |

| Total operating revenues | | | [removed: 7,957] [added: 7,500] | | | | | | [removed: 6,394] [added: 7,957] | | | | | | [removed: 5,794] [added: 6,394] | | |

| Fuel | | | [removed: 473] [added: 514] | | | | | | [removed: 581] [added: 473] | | | | | | [removed: 490] [added: 581] | | |

| Purchased power | | | [removed: 1,547] [added: 1,298] | | | | | | [removed: 606] [added: 1,547] | | | | | | [removed: 513] [added: 606] | | |

| Natural gas purchased for resale | | | [removed: 657] [added: 355] | | | | | | [removed: 442] [added: 657] | | | | | | [removed: 272] [added: 442] | | |

| Other operations and maintenance | | | [removed: 1,937] [added: 1,866] | | | | | | [removed: 1,774] [added: 1,937] | | | | | | [removed: 1,661] [added: 1,774] | | |

| Depreciation and amortization | | | [removed: 1,289] [added: 1,387] | | | | | | [removed: 1,146] [added: 1,289] | | | | | | [removed: 1,075] [added: 1,146] | | |

| Taxes other than income taxes | | | [removed: 539] [added: 522] | | | | | | [removed: 512] [added: 539] | | | | | | [removed: 483] [added: 512] | | |

| Total operating expenses | | | [removed: 6,442] [added: 5,942] | | | | | | [removed: 5,061] [added: 6,442] | | | | | | [removed: 4,494] [added: 5,061] | | |

| Operating Income | | | [removed: 1,515] [added: 1,558] | | | | | | [removed: 1,333] [added: 1,515] | | | | | | [removed: 1,300] [added: 1,333] | | |

| Other Income, Net | | | [removed: 226] [added: 348] | | | | | | [removed: 202] [added: 226] | | | | | | [removed: 151] [added: 202] | | |

| Interest Charges | | | [removed: 486] [added: 566] | | | | | | [removed: 383] [added: 486] | | | | | | [removed: 419] [added: 383] | | |