Cover and table of contents

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K

(Mark One)

☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2025

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Commission File Number						Exact name of registrant as specified in its charter; State or other jurisdiction of incorporation or organization; Address of principal executive offices, including zip code; and Registrant’s telephone number, including area code															IRS Employer Identification No.
1-8962						PINNACLE WEST CAPITAL CORPORATION															86-0512431
						(an Arizona corporation)
						400 North Fifth Street, P.O. Box 53999
						Phoenix			Arizona			85072-3999
						(602)			250-1000
1-4473						ARIZONA PUBLIC SERVICE COMPANY															86-0011170
						(an Arizona corporation)
						400 North Fifth Street, P.O. Box 53999
						Phoenix			Arizona			85072-3999
						(602)			250-1000

Securities registered pursuant to Section 12(b) of the Act:

						Title Of Each Class						Trading Symbol (s)						Name Of Each Exchange On Which Registered
PINNACLE WEST CAPITAL CORPORATION						Common Stock, No Par Value						PNW						New York Stock Exchange

Securities registered pursuant to Section 12(g) of the Act:

ARIZONA PUBLIC SERVICE COMPANY Common Stock, Par Value $2.50 per share

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act

PINNACLE WEST CAPITAL CORPORATION			Yes			☒						No			☐
ARIZONA PUBLIC SERVICE COMPANY			Yes			☒						No			☐

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.

PINNACLE WEST CAPITAL CORPORATION			Yes			☐						No			☒
ARIZONA PUBLIC SERVICE COMPANY			Yes			☐						No			☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

PINNACLE WEST CAPITAL CORPORATION			Yes			☒						No			☐
ARIZONA PUBLIC SERVICE COMPANY			Yes			☒						No			☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).

PINNACLE WEST CAPITAL CORPORATION			Yes			☒						No			☐
ARIZONA PUBLIC SERVICE COMPANY			Yes			☒						No			☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

PINNACLE WEST CAPITAL CORPORATION

Large accelerated filer			☒			Accelerated filer			☐			Non-accelerated filer			☐			Smaller reporting company			☐
Emerging growth company			☐

ARIZONA PUBLIC SERVICE COMPANY

Large accelerated filer			☐			Accelerated filer			☐			Non-accelerated filer			☒			Smaller reporting company			☐
Emerging growth company			☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☒

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. ☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant's executive officers during the relevant recovery period pursuant to §240.10D-1(b). ☐

Indicate by check mark whether each registrant is a shell company (as defined in Rule 12b-2 of the Act).

PINNACLE WEST CAPITAL CORPORATION			Yes			☐						No			☒
ARIZONA PUBLIC SERVICE COMPANY			Yes			☐						No			☒

State the aggregate market value of the voting and non-voting common equity held by non-affiliates, computed by reference to the price at which the common equity was last sold, or the average bid and asked price of such common equity, as of the last business day of each registrant’s most recently completed second fiscal quarter:

PINNACLE WEST CAPITAL CORPORATION						$	10,673,413,436		as of June 30, 2025
ARIZONA PUBLIC SERVICE COMPANY						$	0		as of June 30, 2025

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date.

PINNACLE WEST CAPITAL CORPORATION			Number of shares of common stock, no par value, outstanding as of February 19, 2026:			120,905,390
ARIZONA PUBLIC SERVICE COMPANY			Number of shares of common stock, $2.50 par value, outstanding as of February 19, 2026:			71,264,947

DOCUMENTS INCORPORATED BY REFERENCE

Portions of Pinnacle West Capital Corporation’s definitive Proxy Statement relating to its Annual Meeting of Shareholders to be held on May 14, 2026 are incorporated by reference into Part III hereof.

Arizona Public Service Company meets the conditions set forth in General Instruction I(1)(a) and (b) of Form 10-K and is therefore filing this form with the reduced disclosure format allowed under General Instruction I(2).

TABLE OF CONTENTS

						Page
GLOSSARY OF NAMES AND TECHNICAL TERMS						ii
FORWARD-LOOKING STATEMENTS						1
PART I						3
Item 1.			Business			3
Item 1A.			Risk Factors			32
Item 1B.			Unresolved Staff Comments			46
Item 1C.			Cybersecurity			46
Item 2.			Properties			49
Item 3.			Legal Proceedings			52
Item 4.			Mine Safety Disclosures			52
Information about our Executive Officers						53
PART II						54
Item 5.			Market for Registrants’ Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities			54
Item 6.			[Reserved]			55
Item 7.			Management’s Discussion and Analysis of Financial Condition and Results of Operations			56
Item 7A.			Quantitative and Qualitative Disclosures About Market Risk			84
Item 8.			Financial Statements and Supplementary Data			85
			Pinnacle West Capital Corporation Financial Statements			91
			Arizona Public Service Company Financial Statements			102
Item 9.			Changes in and Disagreements With Accountants on Accounting and Financial Disclosure			200
Item 9A.			Controls and Procedures			200
Item 9B.			Other Information			201
Item 9C.			Disclosure Regarding Foreign Jurisdictions that Prevent Inspections			201
PART III						201
Item 10.			Directors, Executive Officers and Corporate Governance			201
Item 11.			Executive Compensation			201
Item 12.			Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters			201
Item 13.			Certain Relationships and Related Transactions, and Director Independence			203
Item 14.			Principal Accountant Fees and Services			203
PART IV						204
Item 15.			Exhibits and Financial Statement Schedules			204
Item 16.			Form 10-K Summary			216
SIGNATURES						217

This combined Form 10-K is separately filed by Pinnacle West Capital Corporation (“Pinnacle West”) and Arizona Public Service Company (“APS”). Any use of the words “Company,” “we,” “us,” and “our” refer to Pinnacle West unless the context otherwise requires. Each registrant is filing on its own behalf all of the information contained in this Form 10-K that relates to such registrant and, where required, its subsidiaries. Except as stated in the preceding sentence, neither registrant is filing any information that does not relate to such registrant, and therefore makes no representation as to any such information. The information required with respect to each company is set forth within the applicable items. Item 8 of this report includes Consolidated Financial Statements of Pinnacle West and Consolidated Financial Statements of APS. Part II, Item 8 also includes Combined Notes to Consolidated Financial Statements.

i

GLOSSARY OF NAMES AND TECHNICAL TERMS

ACC			Arizona Corporation Commission
ADEQ			Arizona Department of Environmental Quality
AFUDC			Allowance for funds used during construction
AI			Artificial intelligence
ANPP			Arizona Nuclear Power Project, also known as Palo Verde
APS			Arizona Public Service Company, a subsidiary of the Company
ARO			Asset retirement obligations
ASRFP			All-source request for proposal
ASU			Accounting Standards Update
ATM Program			At-the-market equity distribution program
Base Fuel Rate			The portion of APS’s retail base rates attributable to fuel and purchased power costs
BCE			Bright Canyon Energy Corporation
BESS			Battery energy storage system
CAISO			California Independent System Operator
Captive			Captive Insurance Cell
CCR			Coal combustion residuals
CCRMU			Coal combustion residuals management unit
CCS			Carbon capture and sequestration or utilization controls
CERCLA or Superfund			Comprehensive Environmental Response Compensation and Liability Act
Cholla			Cholla Power Plant
DG			Distributed Generation
DOE			United States Department of Energy
DSM			Demand Side Management
EES			Energy Efficiency Standard
El Dorado			El Dorado Investment Company, a subsidiary of the Company
ELG			Effluent Limitation Guidelines
EPA			United States Environmental Protection Agency
FERC			United States Federal Energy Regulatory Commission
Four Corners			Four Corners Power Plant
FRAM			Formula Rate Adjustment Mechanism
GAAP			Accounting principles generally accepted in the United States of America
GHG			Greenhouse gas
GWh			Gigawatt-hour, one billion watts per hour
IRP			Integrated Resource Plan
ITC			Investment Tax Credit
kV			Kilovolt, one thousand volts
kWh			Kilowatt-hour, one thousand watts per hour
LFCR			Lost Fixed Cost Recovery Mechanism
MW			Megawatt, one million watts
MWh			Megawatt-hour, one million watts per hour
NAAQS			National Ambient Air Quality Standards
Native Load			Retail and wholesale sales supplied under traditional cost-based rate regulation
Navajo Plant			Navajo Generating Station
NERC			North American Electric Reliability Corporation
NPDES			National Pollutant Discharge Elimination System
NRC			United States Nuclear Regulatory Commission
NTEC			Navajo Transitional Energy Company, LLC
NEIL			Nuclear Electric Insurance Limited
Ocotillo			Ocotillo Power Plant
Palo Verde			Palo Verde Generating Station or PVGS
PFAS			Per- and polyfluoroalkyl compounds
Pinnacle West			Pinnacle West Capital Corporation (any use of the words “Company,” “we,” “us,” and “our” refer to Pinnacle West unless the context requires otherwise)

ii

PNW Power			Pinnacle West Power, LLC, a subsidiary of the Company
PPA			Power purchase agreement
PSA			Power Supply Adjustor
PTC			Production tax credit
RCRA			Resource Conservation and Recovery Act
Redhawk			Redhawk Power Plant
RES			Renewable Energy Standard
ROD			Record of Decision
ROO			Recommended Opinion and Order
Salt River Project or SRP			Salt River Project Agricultural Improvement and Power District
SCE			Southern California Edison Company
SEC			United States Securities and Exchange Commission
SPP			Southwest Power Pool
SRB			System Reliability Benefit Mechanism
Sundance			Sundance Power Plant
TCA			Transmission cost adjustor
TEAM			Tax expense adjustor mechanism
VIE			Variable interest entity
WEIM			Western Energy Imbalance Market

iii

FORWARD-LOOKING STATEMENTS

This document contains forward-looking statements based on current expectations. These forward-looking statements are often identified by words such as “estimate,” “predict,” “may,” “believe,” “plan,” “expect,” “require,” “intend,” “assume,” “project,” “anticipate,” “goal,” “seek,” “strategy,” “likely,” “should,” “will,” “could,” and similar words. Because actual results may differ materially from expectations, we caution readers not to place undue reliance on these statements. A number of factors could cause future results to differ materially from historical results, or from outcomes currently expected or sought by Pinnacle West or APS. In addition to the Risk Factors described in Part I, Item 1A and in Part II, Item 7 — “Management’s Discussion and Analysis of Financial Condition and Results of Operations” of this report, these factors include, but are not limited to:

• our ability to achieve timely and adequate rate recovery of our costs through our regulated rates and adjustor recovery mechanisms, including returns on and of debt and equity capital investment;

• the impacts of federal, state, and local laws, judicial decisions, statutes, regulations, and FERC, NRC, EPA, ACC, and other agency requirements, including as they are changed by legislative and regulatory action as well as executive orders, such as those relating to tax, environment, energy, nuclear plants, and deregulation of the retail electric market;

• our operation of Palo Verde is subject to substantial regulatory oversight and potentially significant liabilities and capital expenditures;

• we are subject to numerous environmental laws and changes to existing laws, or new laws, may increase our costs and impact our business;

• the potential effects of climate change on our electric system, including as a result of weather extremes, such as prolonged drought and high temperature variations in the area where APS conducts its business, as well as the impacts of policy and regulatory changes introduced to address climate change;

• co-owners of our jointly owned generation and transmission facilities may have unaligned goals;

• the willingness or ability of counterparties, participants, and landowners to meet contractual or other obligations or extend the rights for continued generation and transmission operations;

• deregulation of the electric industry and other factors, such as large customers developing large, utility scale generation to serve their energy needs, may result in increased competition;

• variations in demand for electricity, including those due to weather, seasonality (including large increases in ambient temperatures), the general economy or social conditions, customer and sales growth (or decline), data center growth (or lack thereof), including to support the AI industry, the effects of energy conservation measures and DG, and technological advancements;

• wildfires, including those arising as a result of climate change, extreme weather events, or the expansion of the wildland urban interface;

• generation, transmission, and distribution facilities and system operating costs, conditions, performance, and outages;

• our ability and efforts to meet current and anticipated future needs for generation and transmission and distribution facilities in our region at reliable levels, including factors affecting our ability to acquire and develop new resources to serve this load as well as difficulties in accurately forecasting load growth, particularly from high load energy users;

• availability of fuel and water supplies as well as the volatility and costs of fuel and purchased power;

• the direct or indirect effect on our facilities or business from cybersecurity threats or intrusions, data security breaches, terrorist attack, physical attack, severe storms, or other catastrophic events, such as fires, explosions, pandemic health events, or similar occurrences;

• risks inherent in the operation of nuclear facilities, including spent fuel disposal uncertainty;

• the development of new technologies and the impact they have on the retail and wholesale electricity market and the impacts of our adoption or failure to adopt such technologies;

• the availability and retention of qualified personnel and the need to negotiate collective bargaining agreements with union employees;

• the cost of debt, including increased cost as a result of rising interest rates, and equity capital and our ability to access capital markets when required as well as the impacts a credit rating downgrade would have on us;

• the investment performance of the assets of our nuclear decommissioning trust, captive insurance cell, coal mine reclamation escrow, pension, and other postretirement benefit plans, and the resulting impact on future funding requirements;

• Pinnacle West’s cash flow depends on the performance of APS and its ability to make dividends and distributions;

• potential shortfalls in insurance coverage;

• Pinnacle West’s ability to meet its debt service obligation could be adversely affected because its debt securities are structurally subordinated to the debt securities and obligations of its subsidiaries;

• the liquidity of wholesale power markets and the use of derivative contracts in our business;

• policy changes in Arizona or other states through ballot initiatives or referenda may increase our cost or operations or affect our business plans;

• general economic conditions, such as tariffs, inflation, and other supply chain constraints, as well as uncertainties associated with the current and future economic environment and conditions in Arizona; and

• disruptions in financial markets could adversely affect our cost of and access to credit and capital markets.

These and other factors are discussed in the Risk Factors described in Part I, Item 1A of this report, and in Part II, Item 7 — “Management’s Discussion and Analysis of Financial Condition and Results of Operations” of this report, which readers should review carefully before placing any reliance on our financial statements or disclosures. Neither Pinnacle West nor APS assumes any obligation to update these statements, even if our internal estimates change, except as required by law.

PART I