Item 5. OTHER INFORMATION

Ozone National Ambient Air Quality Standards

On October 1, 2015, EPA finalized revisions to the primary ground-level ozone NAAQS at a level of 70 parts per billion (“ppb”). As ozone standards become more stringent, our fossil generation units will come under increasing pressure to reduce emissions of NOx and volatile organic compounds, and to generate emission offsets for new projects or facility expansions located in ozone nonattainment areas. EPA was expected to designate attainment and nonattainment areas relative to the new 70 ppb standard by October 1, 2017. While EPA took action designating attainment and unclassifiable areas on November 6, 2017, the Agency’s final action designating non-attainment areas was not issued until April 30, 2018. At that time, EPA designated the geographic areas containing Yuma and Phoenix, Arizona as in non-attainment with the 2015 70 ppb ozone NAAQS. The vast majority of APS’s natural gas-fired EGUs are located in these jurisdictions. Areas of Arizona and the Navajo Nation where the remainder of APS’s fossil-fuel fired electric generating unit fleet is located were designated as in attainment. On December 23, 2020, EPA issued a final regulation retaining the current primary NAAQS for ozone, following a required scientific review process. On October 7, 2022, EPA took final action designating Maricopa County, which includes the Phoenix, Arizona metropolitan area, as “moderate” for non-attainment with the governing ozone NAAQS, which provided for an August 3, 2024 attainment “deadline” by which the area would be automatically designated as in “serious” non-attainment unless it achieved the 2015 ozone NAAQS. On November 18, 2025, EPA redesignated the geographic area containing Yuma into attainment for the 2015 Ozone NAAQS.

On November 19, 2025, EPA issued a proposed rule determining that the Phoenix-Mesa area would have met the 2015 ozone NAAQS standard by its August 3, 2024 “Moderate” attainment date, “but for” emissions emanating from outside of the United States. This proposal was subsequently finalized on March 23, 2026. As a result, facilities applying for new or modified permits in Maricopa County can continue under the moderate nonattainment NOx threshold, rather than being subject to more restrictive serious nonattainment limitations. On May 22, 2026, a coalition of Environmental NGOs, including Sierra Club, Center for Biological Diversity, Natural Resources Defense Council, and Public Employees for Environmental Responsibility, filed a petition for review in the Ninth Circuit Court of Appeals challenging the EPA’s final action. APS will continue to monitor this proceeding. At this time, APS is unable to predict the outcome of this litigation.

Rule 10b5-1 Trading Plans

During the fiscal quarter ended June 30, 2026, none of our directors or executive officers adopted or terminated any “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement” as each term is defined in Item 408 of Regulation S-K.