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FAIR VALUE MEASUREMENTS
 12 Months Ended
Dec. 31, 2025
Fair Value Disclosures [Abstract]  
FAIR VALUE MEASUREMENTS FAIR VALUE MEASUREMENTS
Fair value measurements are based on inputs of observable and unobservable market data that a market participant would use in pricing the asset or liability. The use of observable inputs is maximized where available and the use of unobservable inputs is minimized for fair value measurement and reflects a three-tier fair value hierarchy that prioritizes inputs to valuation techniques used for fair value measurement.
•Level 1 consists of observable market data in an active market for identical assets or liabilities.
•Level 2 consists of observable market data, other than that included in Level 1, that is either directly or indirectly observable.
•Level 3 consists of unobservable market data. The input may reflect the assumptions of each Registrant of what a market participant would use in pricing an asset or liability. If there is little available market data, then each Registrant's own assumptions are the best available information.
In the case of multiple inputs being used in a fair value measurement, the lowest level input that is significant to the fair value measurement represents the level in the fair value hierarchy in which the fair value measurement is reported.
Net asset value as a practical expedient is the classification used for assets that do not have readily determined fair values. Fund managers value the assets using various inputs and techniques depending on the nature of the underlying investments.
At December 31, 2025, assets and liabilities measured at fair value on a recurring basis during the period, together with their associated level of the fair value hierarchy, were as follows:
Fair Value Measurements Using
Quoted Prices
in Active
Markets for
Identical
Assets 
Significant
Other
Observable
Inputs
Significant
Unobservable
Inputs
Net Asset
Value as a
Practical
Expedient
At December 31, 2025:(Level 1)(Level 2)(Level 3)(NAV)Total
(in millions)
Southern Company
Assets:
Energy-related derivatives(a)
$4 $60 $— $— $64 
Interest rate derivatives— 8 — — 8 
Foreign currency derivatives— 21 — — 21 
Investments in trusts:(b)
Domestic equity935 278 — — 1,213 
Foreign equity182 225 — — 407 
U.S. Treasury and government agency securities— 398 — — 398 
Municipal bonds— 50 — — 50 
Pooled funds – fixed income— 6 — — 6 
Corporate bonds— 520 — — 520 
Mortgage- and asset-backed securities
— 114 — — 114 
Private equity— — — 192 192 
Cash and cash equivalents1 — — — 1 
Other50 3 — 9 62 
Investments, available for sale:
U.S. Treasury and government agency securities3 12 — — 15 
Corporate bonds1 2 — — 3 
Mortgage- and asset-backed securities
— 5 — — 5 
Cash equivalents
1,080 19 — — 1,099 
Other investments10 34 8 — 52 
Other
— — 11 — 11 
Total$2,266 $1,755 $19 $201 $4,241 
Liabilities:
Energy-related derivatives(a)
$12 $100 $— $— $112 
Interest rate derivatives— 187 — — 187 
Foreign currency derivatives— 22 — — 22 
Contingent consideration3 — 11 — 14 
Other— 13 11 — 24 
Total$15 $322 $22 $— $359 
Fair Value Measurements Using
Quoted Prices
in Active
Markets for
Identical
Assets 
Significant
Other
Observable
Inputs
Significant
Unobservable
Inputs
Net Asset
Value as a
Practical
Expedient
At December 31, 2025:(Level 1)(Level 2)(Level 3)(NAV)Total
(in millions)
Alabama Power
Assets:
Energy-related derivatives
$— $19 $— $— $19 
Nuclear decommissioning trusts:(b)
Domestic equity514 267 — — 781 
Foreign equity182 — — — 182 
U.S. Treasury and government agency securities— 15 — — 15 
Municipal bonds— 1 — — 1 
Corporate bonds— 316 — — 316 
Mortgage- and asset-backed securities
— 31 — — 31 
Private equity — — — 192 192 
Other12 1 — 9 22 
Cash equivalents
273 19 — — 292 
Other investments— 34 — — 34 
Total$981 $703 $— $201 $1,885 
Liabilities:
Energy-related derivatives$— $31 $— $— $31 
Georgia Power
Assets:
Energy-related derivatives$— $18 $— $— $18 
Nuclear decommissioning trusts:(b)
Domestic equity421 1 — — 422 
Foreign equity— 224 — — 224 
U.S. Treasury and government agency securities— 383 — — 383 
Municipal bonds— 49 — — 49 
Corporate bonds— 204 — — 204 
Mortgage- and asset-backed securities
— 83 — — 83 
Other38 2 — — 40 
Cash equivalents20 — — — 20 
Total$479 $964 $— $— $1,443 
Liabilities:
Energy-related derivatives$— $33 $— $— $33 
Fair Value Measurements Using
Quoted Prices
in Active
Markets for
Identical
Assets 
Significant
Other
Observable
Inputs
Significant
Unobservable
Inputs
Net Asset
Value as a
Practical
Expedient
At December 31, 2025:(Level 1)(Level 2)(Level 3)(NAV)Total
(in millions)
Mississippi Power
Assets:
Energy-related derivatives$— $14 $— $— $14 
Cash equivalents12 — — — 12 
Total$12 $14 $— $— $26 
Liabilities:
Energy-related derivatives$— $27 $— $— $27 
Southern Power
Assets:
Energy-related derivatives$— $4 $— $— $4 
Foreign currency derivatives— 17 — — 17 
Other
— — 11 — 11 
Total$— $21 $11 $— $32 
Liabilities:
Energy-related derivatives$— $1 $— $— $1 
Contingent consideration3 — 11 — 14 
Other— 13 11 — 24 
Total$3 $14 $22 $— $39 
Southern Company Gas
Assets:
Energy-related derivatives(a)
$4 $5 $— $— $9 
Non-qualified deferred compensation trusts:
Domestic equity— 10 — — 10 
Foreign equity— 1 — — 1 
Pooled funds - fixed income— 6 — — 6 
Cash and cash equivalents1 — — — 1 
Total$5 $22 $— $— $27 
Liabilities:
Energy-related derivatives(a)
$12 $8 $— $— $20 
Interest rate derivatives— 59 — — 59 
Total$12 $67 $— $— $79 
(a)Excludes cash collateral of $33 million.
(b)Excludes receivables related to investment income, pending investment sales, payables related to pending investment purchases, and currencies. See Note 6 under "Nuclear Decommissioning" for additional information.
At December 31, 2024, assets and liabilities measured at fair value on a recurring basis during the period, together with their associated level of the fair value hierarchy, were as follows:
Fair Value Measurements Using
Quoted Prices
in Active
Markets for
Identical
Assets
Significant
Other
Observable
Inputs
Significant
Unobservable
Inputs
Net Asset
Value as a
Practical
Expedient
At December 31, 2024:(Level 1)(Level 2)(Level 3)(NAV)Total
(in millions)
Southern Company
Assets:
Energy-related derivatives(a)
$12 $77 $— $— $89 
Investments in trusts:(b)
Domestic equity849 250 — — 1,099 
Foreign equity148 175 — — 323 
U.S. Treasury and government agency securities— 371 — — 371 
Municipal bonds— 47 — — 47 
Pooled funds – fixed income— 7 — — 7 
Corporate bonds— 452 — — 452 
Mortgage- and asset-backed securities
— 106 — — 106 
Private equity— — — 181 181 
Cash and cash equivalents1 — — — 1 
Other39 3 — 9 51 
Investment, available for sale:
U.S. Treasury and government agency securities
2 7 — — 9 
Corporate bonds
1 2 — — 3 
Mortgage- and asset-backed securities
— 10 — — 10 
Cash equivalents and restricted cash
533 19 — — 552 
Other investments9 31 8 — 48 
Total$1,594 $1,557 $8 $190 $3,349 
Liabilities:
Energy-related derivatives(a)
$5 $124 $— $— $129 
Interest rate derivatives— 269 — — 269 
Foreign currency derivatives— 218 — — 218 
Contingent consideration3 — 16 — 19 
Other— 13 11 — 24 
Total$8 $624 $27 $— $659 
Fair Value Measurements Using
Quoted Prices
in Active
Markets for
Identical
Assets
Significant
Other
Observable
Inputs
Significant
Unobservable
Inputs
Net Asset
Value as a
Practical
Expedient
At December 31, 2024:(Level 1)(Level 2)(Level 3)(NAV)Total
(in millions)
Alabama Power
Assets:
Energy-related derivatives
$— $26 $— $— $26 
Nuclear decommissioning trusts:(b)
Domestic equity459 241 — — 700 
Foreign equity148 — — — 148 
U.S. Treasury and government agency securities— 16 — — 16 
Municipal bonds— 1 — — 1 
Corporate bonds— 287 — — 287 
Mortgage- and asset-backed securities
— 31 — — 31 
Private equity — — — 181 181 
Other11 1 — 9 21 
Cash equivalents and restricted cash
334 19 — — 353 
Other investments— 31 — — 31 
Total$952 $653 $— $190 $1,795 
Liabilities:
Energy-related derivatives$— $42 $— $— $42 
Georgia Power
Assets:
Energy-related derivatives$— $19 $— $— $19 
Nuclear decommissioning trusts:(b)
Domestic equity390 1 — — 391 
Foreign equity— 174 — — 174 
U.S. Treasury and government agency securities— 355 — — 355 
Municipal bonds— 46 — — 46 
Corporate bonds— 165 — — 165 
Mortgage- and asset-backed securities
— 75 — — 75 
Other28 2 — — 30 
Cash equivalents35 — — — 35 
Total$453 $837 $— $— $1,290 
Liabilities:
Energy-related derivatives$— $42 $— $— $42 
Mississippi Power
Assets:
Energy-related derivatives$— $19 $— $— $19 
Liabilities:
Energy-related derivatives$— $34 $— $— $34 
Fair Value Measurements Using
Quoted Prices
in Active
Markets for
Identical
Assets
Significant
Other
Observable
Inputs
Significant
Unobservable
Inputs
Net Asset
Value as a
Practical
Expedient
At December 31, 2024:(Level 1)(Level 2)(Level 3)(NAV)Total
(in millions)
Southern Power
Assets:
Energy-related derivatives$— $4 $— $— $4 
Cash equivalents51 — — — 51 
Total$51 $4 $— $— $55 
Liabilities:
Foreign currency derivatives— 51 — — 51 
Contingent consideration3 — 16 — 19 
Other— 13 11 — 24 
Total$3 $64 $27 $— $94 
Southern Company Gas
Assets:
Energy-related derivatives(a)
$12 $9 $— $— $21 
Non-qualified deferred compensation trusts:
Domestic equity— 8 — — 8 
Foreign equity— 1 — — 1 
Pooled funds - fixed income— 7 — — 7 
Cash and cash equivalents
1 — — — 1 
Investments, available-for-sale:
U.S. Treasury and government agency securities
2 7 — — 9 
Corporate bonds
1 2 — — 3 
Mortgage- and asset-backed securities
— 10 — — 10 
Cash equivalents22 — — — 22 
Total$38 $44 $— $— $82 
Liabilities:
Energy-related derivatives(a)
$5 $6 $— $— $11 
Interest rate derivatives— 84 — — 84 
Total$5 $90 $— $— $95 
(a)Excludes cash collateral of $17 million.
(b)Excludes receivables related to investment income, pending investment sales, payables related to pending investment purchases, and currencies. See Note 6 under "Nuclear Decommissioning" for additional information.
Valuation Methodologies
The energy-related derivatives primarily consist of exchange-traded and OTC financial products for natural gas and physical power products, including, from time to time, basis swaps. These are standard products used within the energy industry and are valued using the market approach. The inputs used are mainly from observable market sources, such as forward natural gas prices, power prices, implied volatility, and overnight index swap interest rates. Interest rate derivatives are also standard OTC products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms,
counterparty credit risk, and, occasionally, implied volatility of interest rate options. The fair value of cross-currency swaps reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future foreign currency exchange rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and discount rates. The interest rate derivatives and cross-currency swaps are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note 14 for additional information on how these derivatives are used.
For fair value measurements of the investments within the nuclear decommissioning trusts and the non-qualified deferred compensation trusts, external pricing vendors are designated for each asset class with each security specifically assigned a primary pricing source. For investments held within commingled funds, fair value is determined at the end of each business day through the net asset value, which is established by obtaining the underlying securities' individual prices from the primary pricing source. A market price secured from the primary source vendor is then evaluated by management in its valuation of the assets within the trusts. As a general approach, fixed income market pricing vendors gather market data (including indices and market research reports) and integrate relative credit information, observed market movements, and sector news into proprietary pricing models, pricing systems, and mathematical tools. Dealer quotes and other market information, including live trading levels and pricing analysts' judgments, are also obtained when available.
The NRC requires licensees of commissioned nuclear power reactors to establish a plan for providing reasonable assurance of funds for future decommissioning. See Note 6 under "Nuclear Decommissioning" for additional information.
Southern Company's investments, available for sale relate to a wholly-owned subsidiary that insures various risk exposures of Southern Company and its subsidiaries. Corporate and municipal bonds, government agency securities, and commercial paper are valued using pricing models maximizing the use of observable inputs for similar securities, including basing value on yields currently available on comparable securities of issues with similar credit ratings. Mortgage- and asset-backed securities are valued through an analysis of the underlying assets and a review of the documentation, including financials, the manager's valuation methodology in valuing their underlying assets, the types of assets and risks involved, and the investor's exit and termination parameters.
Southern Power has contingent payment obligations related to two of its acquisitions whereby it is primarily obligated to make generation-based payments to the seller, commencing at the commercial operation of each facility and continuing through 2026 and 2036, respectively. The obligations are primarily categorized as Level 3 under Fair Value Measurements as the fair value is determined using significant unobservable inputs for the forecasted facility's generation in MW-hours, as well as other inputs such as a fixed dollar amount per MW-hour, and a discount rate. The fair value of the obligations reflects the net present value of expected payments and any periodic change arising from forecasted generation is expected to be immaterial.
Southern Power also has payment obligations through 2040 whereby it must reimburse the transmission owners for interconnection facilities and network upgrades constructed to support connection of a Southern Power generating facility to the transmission system. The obligations are categorized as Level 2 under Fair Value Measurements as the fair value is determined using observable inputs for the contracted amounts and reimbursement period, as well as a discount rate. The fair value of the obligations reflects the net present value of expected payments.
"Other investments" primarily includes investments traded in the open market that have maturities greater than 90 days, which are categorized as Level 2 under Fair Value Measurements and are comprised of corporate bonds, bank certificates of deposit, treasury bonds, and/or agency bonds.
The fair value measurements of private market investments held in Alabama Power's nuclear decommissioning trusts that are calculated at net asset value per share (or its equivalent) as a practical expedient totaled $201 million and $190 million at December 31, 2025 and 2024, respectively. Unfunded commitments related to the private market investments totaled $83 million and $78 million at December 31, 2025 and 2024, respectively. Private market investments include high-quality private equity funds across several market sectors, funds that invest in real estate assets, and a private credit fund. Private market funds do not have redemption rights. Distributions from these funds will be received as the underlying investments in the funds are liquidated.
At December 31, 2025 and 2024, other financial instruments for which the carrying amount did not equal fair value were as follows:
Southern
   Company(*)
Alabama
Power
Georgia
Power
Mississippi
Power
Southern
Power
Southern
Company
   Gas(*)
(in billions)
At December 31, 2025:
Long-term debt, including securities due within one year:
Carrying amount$71.1 $12.0 $20.8 $1.8 $2.9 $9.3 
Fair value67.2 10.9 19.4 1.6 2.9 8.4 
At December 31, 2024:
Long-term debt, including securities due within one year:
Carrying amount$63.2 $11.2 $18.1 $1.7 $2.7 $8.5 
Fair value57.7 9.8 16.2 1.5 2.6 7.4 
(*)The carrying amount of Southern Company Gas' long-term debt includes fair value adjustments from the effective date of the 2016 merger with Southern Company. Southern Company Gas amortizes the fair value adjustments over the remaining lives of the respective bonds, the latest being through 2043.
The fair values are determined using Level 2 measurements and are based on quoted market prices for the same or similar issues or on the current rates available to the Registrants.