EDISON INTERNATIONAL

SCE obtains the power, energy, and local grid support needed to serve its customers primarily from purchases from external parties. SCE estimates that approximately 15% of power delivered to SCE's customers in 2025 came from SCE's own generating facilities.

Natural Gas Supply

SCE requires natural gas to fuel its Mountainview and peaker plants, which are generation units that operate in response to wholesale market signals related to power prices and reliability needs. The physical natural gas purchased by SCE is sourced in competitive interstate markets at trading points on the SoCalGas local distribution company system. SoCalGas is the primary provider of intrastate pipeline transportation service to the gas-fueled generation stations that SCE controls. In 2015 – 2016, SoCalGas experienced a significant natural gas fuel leak at its Aliso Canyon underground gas storage facility that resulted in reduced capacity and usage of the facility. Currently, Aliso Canyon is authorized to operate at up to 79% of its maximum capacity. CPUC has established a biennial assessment process to evaluate the reliability and cost impacts of minimizing or eliminating reliance on Aliso Canyon. To date, SCE has found that gas storage-use restrictions combined with SoCalGas pipeline maintenance constraints contributed to increased electricity costs for customers but did not impact grid reliability. However, there is no certainty that these restrictions or pipeline constraints will not impact grid reliability in the future. Price increases faced by customers would not affect SCE's earnings because SCE expects recovery of these costs through the ERRA balancing account or other CPUC approved procurement plans. However, these higher prices may impact cash flow due to the timing of those recoveries. For more information on cost-recovery mechanisms, see "—Overview of Ratemaking Process" above. SCE is actively monitoring legislative and regulatory processes that are addressing pipeline and electric grid operations impacted by the Aliso Canyon leak, including the CPUC’s biennial assessment process for considering changes to the facility's maximum inventory. SCE has also made additional procurement efforts to alleviate the impact of the partial closure of Aliso Canyon, including accelerating existing contracts for new capacity, procuring energy storage from third-parties, contracting for design, build, and transfer of utility-owned storage, procuring additional demand response and contracting for firm gas transportation capacity.

CAISO Wholesale Energy Market

The CAISO operates a wholesale energy market primarily in California through which competing electricity generators offer their electricity output to market participants, including electricity retailers. The CAISO schedules power in hourly increments with hourly prices through a day-ahead market in California and schedules power in fifteen-minute and five-minute increments with fifteen-minute and five-minute prices through two real-time markets that cover California and portions of ten neighboring states through the Western Energy Imbalance Market. Both markets optimize energy procurement, ancillary service procurement, unit commitment and congestion management. SCE participates in the day-ahead and real-time markets for the sale of its own generation and generation under contract and for purchases for its load requirements. In December 2023, the FERC approved an Extended Day-Ahead Market ("EDAM"), giving utilities outside the CAISO the option of joining a centralized day-ahead market run by the CAISO. The EDAM, which is currently scheduled to go-live in May 2026, gives utilities an opportunity to lock in energy prices a day in advance, and thereby substantially avoid volatility in the real-time energy market.

The CPUC's Resource Adequacy program imposes resource adequacy requirements on load-serving entities like SCE that are designed to provide sufficient resources to the CAISO to ensure the safe and reliable operation of the grid in real time. All load-serving entities are responsible for meeting the system resource adequacy requirements for the load they serve, plus an additional amount that is referred to as a planning reserve margin. The CPUC has also adopted a central procurement structure in SCE's distribution service area for local resource adequacy that transfers the responsibility for procuring local resource adequacy from other local load-serving entities to SCE as a central procurement entity ("CPE") for its distribution service area. Under this structure, while SCE procures local resource adequacy to meet the local resource adequacy requirement for its distribution service area, other load-serving entities can also procure their own local resources. Load-serving entities ("LSE") that procure their own local resources can sell the capacity to the CPE, and utilize the resources.

Following state-wide rotating outages in August 2020 that impacted a significant number of SCE's customers, the CPUC has taken action towards ensuring reliable electric service in the event that extreme heat events occur during summer. The CPUC has issued decisions requiring at least an aggregate of 15,500 MW of additional net qualifying renewable or zero-emitting capacity to be procured collectively by all of the load-serving entities subject to the CPUC’s Integrated Resource Planning purview. The aggregate additional capacity is required by 2028, with 2,000 MW required by 2023, an additional 6,000 MW required by 2024, an additional 1,500 MW required by 2025, an additional 2,000 MW required by 2026, an additional 2,000 MW required by 2027, and an additional 2,000 MW of long-lead time resources, comprised of 1,000 MW of long-duration storage and 1,000 MW of firm zero-emitting resources required by 2028; 2,500 MW of the aggregate procurement requirement through 2025 must be through generation or generation paired with storage.

SCE's allocation of the requirements is 705 MW by 2023, 2,114 MW by 2024, 529 MW by 2025, 684 MW by 2026, 684 MW by 2027, and 705 MW of long-lead time resources, comprised of 353 MW of long-duration storage and 352 MW of firm zero-emitting resources by 2028, for a total of 5,421 MW; 880 MW of the aggregate procurement requirement through 2025 must be through generation or generation paired with storage.

As of December 31, 2025, SCE has executed sufficient long‑term contracts to meet all of these procurement requirements, including renewable and zero‑emitting resources, long‑duration storage and geothermal resources. In addition, SCE has executed contracts sufficient to meet its 880 MW procurement requirement for generation or generation paired with storage due in 2025, although certain projects are not expected to achieve commercial operation until 2026 or 2027. In September 2025, the CPUC established conditions under which delayed procurement may still be deemed compliant for up to three years after a required online date if the LSE has executed sufficient long‑term contracts and meets their month‑ahead system resource adequacy obligations during the delay. SCE expects to utilize this alternative compliance mechanism to address remaining delays in meeting applicable procurement requirements.

In February 2024, the CPUC adopted a decision approving SCE’s integrated resource plan identifying the resources needed to meet California’s greenhouse gas emissions and reliability targets and authorizing SCE to procure the resource needs identified in its plan. Additionally, the CPUC approved a process to request extensions of the 2028 procurement requirement for long-duration storage and firm zero-emitting resources to no later than 2031.