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SOUTHERN CO

For the period ended Dec 31, 2023. Filed Feb 15, 2024.

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About this filing

A company's yearly report to the SEC, with audited financial statements. It is the fullest account a company gives of its business, its finances and the risks it sees.

FY2023 · Filed Feb 15, 2024

SO$93.57+1.3%Stored close · as of Nov 9, 2026

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Contents

Retirement Benefits

  1. RETIREMENT BENEFITS

The Southern Company system has a qualified defined benefit, trusteed pension plan covering substantially all employees, with the exception of PowerSecure employees. The qualified pension plan is funded in accordance with requirements of the Employee Retirement Income Security Act of 1974, as amended (ERISA). No contributions to the qualified pension plan were made for the year ended December 31, 2023 andno mandatory contributions to the qualified pension plan are anticipated for the year ending December 31, 2024. The Southern Company system also provides certain non-qualified defined benefits for a select group of management and highly compensated employees, which are funded on a cash basis. In addition, the Southern Company system provides certain medical care and life insurance benefits for retired employees through other postretirement benefit plans. The traditional electric operating companies fund other postretirement trusts to the extent required by their respective regulatory

II-201 commissions. Southern Company Gas has a separate unfunded supplemental retirement health care plan that provides medical care and life insurance benefits to employees of discontinued businesses. For the year ending December 31, 2024, no contributions to any other postretirement trusts are expected.

Actuarial Assumptions

The weighted average rates assumed in the actuarial calculations used to determine both the net periodic costs for the pension and other postretirement benefit plans for the following year and the benefit obligations as of the measurement date are presented below.

2023
Assumptions used to determine netperiodic costs:Southern CompanyAlabama PowerGeorgiaPowerMississippi PowerSouthern PowerSouthern Company Gas
Pension plans
Discount rate – benefit obligations5.25%5.26%5.25%5.25%5.31%5.24%
Discount rate – interest costs5.135.145.125.125.195.12
Discount rate – service costs5.365.385.385.375.375.31
Expected long-term return on plan assets8.408.408.408.408.408.40
Annual salary increase4.804.804.804.804.804.80
Other postretirement benefit plans
Discount rate – benefit obligations5.18%5.20%5.17%5.17%5.24%5.16%
Discount rate – interest costs5.085.095.075.085.125.07
Discount rate – service costs5.345.355.345.335.335.33
Expected long-term return on plan assets7.677.957.497.43—6.59
Annual salary increase4.804.804.804.804.804.80
2022
Assumptions used to determine netperiodic costs:Southern CompanyAlabamaPowerGeorgiaPowerMississippi PowerSouthern PowerSouthern Company Gas
Pension plans
Discount rate – benefit obligations3.09%3.12%3.07%3.07%3.21%3.04%
Discount rate – interest costs2.552.582.512.542.792.53
Discount rate – service costs3.343.363.373.353.363.21
Expected long-term return on plan assets8.258.258.258.258.258.25
Annual salary increase4.804.804.804.804.804.80
Other postretirement benefit plans
Discount rate – benefit obligations2.90%2.95%2.87%2.88%3.07%2.82%
Discount rate – interest costs2.322.382.302.272.552.17
Discount rate – service costs3.263.303.273.263.253.22
Expected long-term return on plan assets7.217.546.887.22—6.08
Annual salary increase4.804.804.804.804.804.80

II-202

2021
Assumptions used to determine net periodic costs:Southern CompanyAlabamaPowerGeorgiaPowerMississippi PowerSouthern PowerSouthern Company Gas
Pension plans
Discount rate – benefit obligations2.81%2.85%2.79%2.80%2.99%2.75%
Discount rate – interest costs2.132.172.092.122.462.10
Discount rate – service costs3.183.233.213.203.222.97
Expected long-term return on plan assets8.258.258.258.258.258.25
Annual salary increase4.804.804.804.804.804.80
Other postretirement benefit plans
Discount rate – benefit obligations2.56%2.63%2.52%2.53%2.78%2.46%
Discount rate – interest costs1.841.911.821.782.121.64
Discount rate – service costs3.073.133.083.063.053.01
Expected long-term return on plan assets7.097.186.846.98—6.54
Annual salary increase4.804.804.804.804.804.80
2023
Assumptions used to determine benefit obligations:Southern CompanyAlabama PowerGeorgia PowerMississippi PowerSouthern PowerSouthern Company Gas
Pension plans
Discount rate5.07%5.08%5.06%5.06%5.14%5.05%
Annual salary increase4.604.604.604.604.604.60
Other postretirement benefit plans
Discount rate4.99%5.01%4.98%4.98%5.06%4.98%
Annual salary increase4.604.604.604.604.604.60
2022
Assumptions used to determine benefit obligations:Southern CompanyAlabama PowerGeorgia PowerMississippi PowerSouthern PowerSouthern Company Gas
Pension plans
Discount rate5.25%5.26%5.25%5.25%5.31%5.24%
Annual salary increase4.804.804.804.804.804.80
Other postretirement benefit plans
Discount rate5.18%5.20%5.17%5.17%5.24%5.16%
Annual salary increase4.804.804.804.804.804.80

The Registrants estimate the expected rate of return on pension plan and other postretirement benefit plan assets using a financial model to project the expected return on each current investment portfolio. The analysis projects an expected rate of return on each of the different asset classes in order to arrive at the expected return on the entire portfolio relying on each trust's target asset allocation and reasonable capital market assumptions. The financial model is based on four key inputs: anticipated returns by asset class (based in part on historical returns), each trust's target asset allocation, an anticipated inflation rate, and the projected impact of a periodic rebalancing of each trust's portfolio. The Registrants set the expected rate of return assumption using an arithmetic mean which represents the expected simple average return to be earned by the pension plan assets over any one year. The Registrants believe the use of the arithmetic mean is more compatible with the expected rate of return's function of estimating a single year's investment return.

II-203

An additional assumption used in measuring the accumulated other postretirement benefit obligations (APBO) was a weighted average medical care cost trend rate. The weighted average medical care cost trend rates used in measuring the APBO for the Registrants at December 31, 2023 were as follows:

Initial Cost Trend RateUltimate Cost Trend RateYear That Ultimate Rate is Reached
Pre-657.00%4.50%2032
Post-65 medical5.504.502032
Post-65 prescription8.504.502032

Pension Plans

The total accumulated benefit obligation for the pension plans at December 31, 2023 and 2022 was as follows:

Southern CompanyAlabama PowerGeorgia PowerMississippi PowerSouthern PowerSouthern Company Gas
(in millions)
December 31, 2023$11,991$2,746$3,674$546$145$808
December 31, 202211,4222,6013,534520135801

An actuarial loss of $0.5 billion and an actuarial gain of $3.9 billion were recorded for the annual remeasurement of the Southern Company system pension plans at December 31, 2023 and 2022, respectively, primarily due to a decrease of 18 basis points and an increase of 216 basis points, respectively, in the overall discount rate used to calculate the benefit obligation as a result of higher market interest rates.

Changes in the projected benefit obligations and the fair value of plan assets during the plan years ended December 31, 2023 and 2022 were as follows:

2023
Southern CompanyAlabama PowerGeorgiaPowerMississippi PowerSouthern PowerSouthern Company Gas
(in millions)
Change in benefit obligation
Benefit obligation at beginning of year$12,602$2,906$3,851$569$163$868
Service cost275646811624
Interest cost62614519128842
Benefits paid(744)(155)(224)(32)(6)(104)
Actuarial loss49311612323652
Balance at end of year13,2523,0764,009599177882
Change in plan assets
Fair value of plan assets at beginning of year14,2183,4274,4566491781,002
Actual return on plan assets1,092260331501279
Employer contributions52119223
Benefits paid(744)(154)(225)(32)(7)(104)
Fair value of plan assets at end of year14,6183,5444,571669185980
Accrued asset$1,366$468$562$70$8$98

II-204

2022
Southern CompanyAlabama PowerGeorgiaPowerMississippi PowerSouthern PowerSouthern Company Gas
(in millions)
Change in benefit obligation
Benefit obligation at beginning of year$16,382$3,806$5,012$743$222$1,134
Service cost4129910317934
Interest cost4089612318628
Benefits paid(692)(144)(226)(30)(5)(75)
Actuarial gain(3,908)(951)(1,161)(179)(69)(253)
Balance at end of year12,6022,9063,851569163868
Change in plan assets
Fair value of plan assets at beginning of year17,2254,1415,4157862131,241
Actual loss on plan assets(2,376)(579)(753)(110)(31)(167)
Employer contributions61920313
Benefits paid(692)(144)(226)(30)(5)(75)
Fair value of plan assets at end of year14,2183,4274,4566491781,002
Accrued asset$1,616$521$605$80$15$134

The projected benefit obligations for the qualified and non-qualified pension plans at December 31, 2023 are shown in the following table. All pension plan assets are related to the qualified pension plan.

Southern CompanyAlabama PowerGeorgia PowerMississippi PowerSouthern PowerSouthern Company Gas
(in millions)
Projected benefit obligations:
Qualified pension plan$12,540$2,959$3,865$569$154$822
Non-qualified pension plan713117145292260

II-205

Amounts recognized in the balance sheets at December 31, 2023 and 2022 related to the Registrants' pension plans consist of the following:

SouthernCompanyAlabama PowerGeorgiaPowerMississippi PowerSouthern PowerSouthern Company Gas
(in millions)
December 31, 2023:
Prepaid pension costs(a)$2,079$585$706$99$31$158
Other regulatory assets, deferred(b)2,9608211,051152—143
Other current liabilities(64)(11)(13)(2)(2)(3)
Employee benefit obligations(c)(649)(106)(131)(27)(21)(58)
Other regulatory liabilities, deferred(47)—————
AOCI79———20(45)
December 31, 2022:
Prepaid pension costs(a)$2,290$629$738$108$37$183
Other regulatory assets, deferred(b)2,455679887123—111
Other current liabilities(56)(10)(12)(2)(2)(3)
Employee benefit obligations(c)(618)(98)(121)(26)(20)(42)
Other regulatory liabilities, deferred(85)—————
AOCI24———11(75)

(a)Included in prepaid pension and other postretirement benefit costs on Alabama Power's balance sheet and other deferred charges and assets on Southern Power's consolidated balance sheet.

(b)Amounts for Southern Company exclude regulatory assets of $173 million and $190 million at December 31, 2023 and 2022, respectively, associated with unamortized amounts in Southern Company Gas' pension plans prior to its acquisition by Southern Company.

(c)Included in other deferred credits and liabilities on Southern Power's consolidated balance sheets.

Presented below are the amounts included in regulatory assets at December 31, 2023 and 2022 related to the portion of the defined benefit pension plan attributable to Southern Company, the traditional electric operating companies, and Southern Company Gas that had not yet been recognized in net periodic pension cost.

SouthernCompanyAlabama PowerGeorgiaPowerMississippi PowerSouthern Company Gas
(in millions)
Regulatory assets:
Prior service cost$9$4$6$1$(7)
Net loss2,9048171,045151100
Regulatory amortization————50
Total regulatory assets(*)$2,913$821$1,051$152$143
Regulatory assets:
Prior service cost$10$4$7$1$(9)
Net loss2,36167588012266
Regulatory amortization————54
Total regulatory assets(*)$2,371$679$887$123$111

(*)Amounts for Southern Company exclude regulatory assets of $173 million and $190 million at December 31, 2023 and 2022, respectively, associated with unamortized amounts in Southern Company Gas' pension plans prior to its acquisition by Southern Company.

II-206

The changes in the balance of regulatory assets related to the portion of the defined benefit pension plan attributable to Southern Company, the traditional electric operating companies, and Southern Company Gas for the years ended December 31, 2023 and 2022 are presented in the following table:

SouthernCompanyAlabama PowerGeorgiaPowerMississippi PowerSouthern Company Gas
(in millions)
Regulatory assets (liabilities):(*)
Balance at December 31, 2021$2,801$809$971$146$91
Net (gain) loss(183)(67)(9)(12)27
Reclassification adjustments:
Amortization of prior service costs(1)(1)(1)—2
Amortization of net gain (loss)(246)(62)(74)(11)1
Amortization of regulatory assets(*)————(10)
Total reclassification adjustments(247)(63)(75)(11)(7)
Total change(430)(130)(84)(23)20
Balance at December 31, 2022$2,371$679$887$123$111
Net loss5761531783134
Reclassification adjustments:
Amortization of prior service costs(1)(1)(1)—2
Amortization of net loss(33)(10)(13)(2)—
Amortization of regulatory assets(*)————(4)
Total reclassification adjustments(34)(11)(14)(2)(2)
Total change5421421642932
Balance at December 31, 2023$2,913$821$1,051$152$143

(*)Amounts for Southern Company exclude regulatory assets of $173 million and $190 million at December 31, 2023 and 2022, respectively, associated with unamortized amounts in Southern Company Gas' pension plans prior to its acquisition by Southern Company.

Presented below are the amounts included in AOCI at December 31, 2023 and 2022 related to the portion of the defined benefit pension plan attributable to Southern Company, Southern Power, and Southern Company Gas that had not yet been recognized in net periodic pension cost.

SouthernCompanySouthernPowerSouthern CompanyGas
(in millions)
AOCI:
Prior service cost$(1)$—$(2)
Net (gain) loss8020(43)
Total AOCI$79$20$(45)
AOCI:
Prior service cost$(2)$—$(3)
Net (gain) loss2611(72)
Total AOCI$24$11$(75)

II-207

The components of OCI related to the portion of the defined benefit pension plan attributable to Southern Company, Southern Power, and Southern Company Gas for the years ended December 31, 2023 and 2022 are presented in the following table:

Southern CompanySouthernPowerSouthern CompanyGas
(in millions)
AOCI:
Balance at December 31, 2021$100$35$(45)
Net gain(82)(22)(30)
Reclassification adjustments:
Amortization of net gain (loss)6(2)—
Total change(76)(24)(30)
Balance at December 31, 2022$24$11$(75)
Net loss62929
Reclassification adjustments:
Amortization of prior service costs1—1
Amortization of net loss(8)——
Total reclassification adjustments(7)—1
Total change55930
Balance at December 31, 2023$79$20$(45)

II-208

Components of net periodic pension cost for the Registrants were as follows:

Southern CompanyAlabama PowerGeorgiaPowerMississippi PowerSouthern PowerSouthern Company Gas
(in millions)
Service cost$275$64$68$11$6$24
Interest cost62614519128842
Expected return on plan assets(1,229)(297)(385)(56)(15)(85)
Recognized net (gain) loss329132—(5)
Net amortization—11——15
Prior service cost—————(3)
Net periodic pension cost (income)$(296)$(78)$(112)$(15)$(1)$(12)
Service cost$412$99$103$17$9$34
Interest cost4089612318628
Expected return on plan assets(1,265)(306)(399)(57)(15)(91)
Recognized net loss24062751128
Net amortization—11——15
Prior service cost—————(3)
Net periodic pension cost (income)$(205)$(48)$(97)$(11)$2$(9)
Service cost$434$102$112$18$10$37
Interest cost3468210416524
Expected return on plan assets(1,191)(287)(375)(55)(14)(86)
Recognized net loss3148210015313
Net amortization111——15
Prior service cost—————(3)
Net periodic pension cost (income)$(96)$(20)$(58)$(6)$4$—

The service cost component of net periodic pension cost is included in operations and maintenance expenses and all other components of net periodic pension cost are included in other income (expense), net in the Registrants' statements of income.

Net periodic pension cost is the sum of service cost, interest cost, and other costs netted against the expected return on plan assets. The expected return on plan assets is determined by multiplying the expected rate of return on plan assets and the market-related value of plan assets. In determining the market-related value of plan assets, the Registrants have elected to amortize changes in the market value of return-seeking plan assets over five years and to recognize the changes in the market value of liability-hedging plan assets immediately. Given the significant concentration in return-seeking plan assets, the accounting value of plan assets that is used to calculate the expected return on plan assets differs from the current fair value of the plan assets.

II-209

Future benefit payments reflect expected future service and are estimated based on assumptions used to measure the projected benefit obligation for the pension plans. At December 31, 2023, estimated benefit payments were as follows:

Southern Company · Alabama Power · GeorgiaPower · Mississippi Power · Southern Power · Southern Company Gas
(in millions)
Benefit Payments:
2024$748$164$241$33$7$57
202577617124834759
202680117725436860
202782218225737862
202884018726038764
2029 to 20334,4179881,33720147336

Other Postretirement Benefits

Changes in the APBO and the fair value of the Registrants' plan assets during the plan years ended December 31, 2023 and 2022 were as follows:

2023
Southern CompanyAlabama PowerGeorgiaPowerMississippi PowerSouthern PowerSouthern Company Gas
(in millions)
Change in benefit obligation
Benefit obligation at beginning of year$1,441$344$514$59$9$179
Service cost15441—1
Interest cost7017253—9
Benefits paid(107)(24)(36)(4)(1)(18)
Actuarial (gain) loss(33)(12)(18)(2)11
Balance at end of year1,386329489579172
Change in plan assets
Fair value of plan assets at beginning of year99837236824—113
Actual return on plan assets13152512—19
Employer contributions733273114
Benefits paid(107)(24)(36)(4)(1)(18)
Fair value of plan assets at end of year1,09540341025—128
Accrued asset (liability)$(291)$74$(79)$(32)$(9)$(44)

II-210

2022
Southern CompanyAlabama PowerGeorgiaPowerMississippi PowerSouthern PowerSouthern Company Gas
(in millions)
Change in benefit obligation
Benefit obligation at beginning of year$1,849$440$656$76$11$237
Service cost23661—1
Interest cost4210152—5
Benefits paid(109)(23)(38)(4)(1)(18)
Actuarial gain(365)(89)(125)(16)(1)(46)
Retiree drug subsidy1—————
Balance at end of year1,441344514599179
Change in plan assets
Fair value of plan assets at beginning of year1,25148945029—143
Actual loss on plan assets(218)(98)(71)(4)—(25)
Employer contributions734273113
Benefits paid(108)(23)(38)(4)(1)(18)
Fair value of plan assets at end of year99837236824—113
Accrued asset (liability)$(443)$28$(146)$(35)$(9)$(66)

Amounts recognized in the balance sheets at December 31, 2023 and 2022 related to the Registrants' other postretirement benefit plans consist of the following:

Southern CompanyAlabama PowerGeorgiaPowerMississippi PowerSouthernPowerSouthern Company Gas
(in millions)
December 31, 2023:
Prepaid other postretirement benefit costs(a)$—$74$—$—$—$—
Other regulatory assets, deferred(b)23—11———
Other current liabilities(6)———(1)—
Employee benefit obligations(c)(285)—(79)(32)(8)(44)
Other regulatory liabilities, deferred(231)(48)(85)(10)—(68)
AOCI(9)———1(10)
December 31, 2022:
Prepaid other postretirement benefit costs(a)$—$28$—$—$—$—
Other regulatory assets, deferred(b)34—19———
Other current liabilities(6)———(1)—
Employee benefit obligations(c)(437)—(146)(35)(8)(66)
Other regulatory liabilities, deferred(170)(21)(58)(9)—(58)
AOCI(4)————(2)

(a)Included in prepaid pension and other postretirement benefit costs on Alabama Power's balance sheet.

(b)Amounts for Southern Company exclude regulatory assets of $24 million and $32 million at December 31, 2023 and 2022, respectively, associated with unamortized amounts in Southern Company Gas' other postretirement benefit plans prior to its acquisition by Southern Company.

(c)Included in other deferred credits and liabilities on Southern Power's consolidated balance sheets.

II-211

Presented below are the amounts included in net regulatory assets (liabilities) at December 31, 2023 and 2022 related to the other postretirement benefit plans of Southern Company, the traditional electric operating companies, and Southern Company Gas that had not yet been recognized in net periodic other postretirement benefit cost.

Southern CompanyAlabama PowerGeorgiaPowerMississippi PowerSouthern Company Gas
(in millions)
Balance at December 31, 2023:
Regulatory assets (liabilities):
Prior service cost$13$4$5$1$—
Net gain(216)(52)(79)(11)(64)
Regulatory amortization————(4)
Total regulatory assets (liabilities)(*)$(203)$(48)$(74)$(10)$(68)
Balance at December 31, 2022:
Regulatory assets (liabilities):
Prior service cost$14$4$6$1$1
Net gain(150)(25)(45)(10)(64)
Regulatory amortization————5
Total regulatory assets (liabilities)(*)$(136)$(21)$(39)$(9)$(58)

(*)Amounts for Southern Company exclude regulatory assets of $24 million and $32 million at December 31, 2023 and 2022, respectively, associated with unamortized amounts in Southern Company Gas' other postretirement benefit plans prior to its acquisition by Southern Company.

The changes in the balance of net regulatory assets (liabilities) related to the other postretirement benefit plans for the plan years ended December 31, 2023 and 2022 are presented in the following table:

Southern CompanyAlabama PowerGeorgiaPowerMississippi PowerSouthern Company Gas
(in millions)
Net regulatory assets (liabilities):(*)
Balance at December 31, 2021$(74)$(62)$(10)$1$(34)
Net (gain) loss(64)41(27)(10)(13)
Reclassification adjustments:
Amortization of prior service costs1————
Amortization of net gain (loss)1—(2)——
Amortization of regulatory assets(*)————(11)
Total reclassification adjustments2—(2)—(11)
Total change(62)41(29)(10)(24)
Balance at December 31, 2022$(136)$(21)$(39)$(9)$(58)
Net gain(77)(30)(38)(1)—
Reclassification adjustments:
Amortization of prior service costs(1)—(1)——
Amortization of net gain634——
Amortization of regulatory assets(*)————(10)
Total reclassification adjustments533—(10)
Total change(72)(27)(35)(1)(10)
Balance at December 31, 2023$(208)$(48)$(74)$(10)$(68)

(*)Amounts for Southern Company exclude regulatory assets of $24 million and $32 million at December 31, 2023 and 2022, respectively, associated with unamortized amounts in Southern Company Gas' other postretirement benefit plans prior to its acquisition by Southern Company.

II-212

Presented below are the amounts included in AOCI at December 31, 2023 and 2022 related to the other postretirement benefit plans of Southern Company, Southern Power, and Southern Company Gas that had not yet been recognized in net periodic other postretirement benefit cost.

SouthernCompanySouthernPowerSouthern CompanyGas
(in millions)
AOCI:
Prior service cost$1$—$—
Net (gain) loss(10)1(10)
Total AOCI$(9)$1$(10)
AOCI:
Prior service cost$1$—$—
Net (gain) loss(5)—(2)
Total AOCI$(4)$—$(2)

The components of OCI related to the other postretirement benefit plans for the plan years ended December 31, 2023 and 2022 are presented in the following table:

Southern CompanySouthernPowerSouthern Company Gas
(in millions)
AOCI:
Balance at December 31, 2021$—$2$(5)
Net gain(3)(2)—
Reclassification adjustments:
Amortization of net gain (loss)(1)—3
Total change(4)(2)3
Balance at December 31, 2022$(4)$—$(2)
Net (gain) loss(12)1—
Reclassification adjustments:
Amortization of net gain (loss)7—(8)
Total change(5)1(8)
Balance at December 31, 2023$(9)$1$(10)

II-213

Components of the other postretirement benefit plans' net periodic cost for the Registrants were as follows:

Southern CompanyAlabama PowerGeorgiaPowerMississippi PowerSouthern PowerSouthern Company Gas
(in millions)
Service cost$15$4$4$1$—$1
Interest cost7017253—9
Expected return on plan assets(83)(33)(29)(3)1(10)
Net amortization(11)(3)(3)——6
Net periodic postretirement benefit cost (income)$(9)$(15)$(3)$1$1$6
Service cost$23$6$6$1$—$1
Interest cost4210152—5
Expected return on plan assets(80)(32)(28)(2)1(9)
Net amortization(1)—2——6
Net periodic postretirement benefit cost (income)$(16)$(16)$(5)$1$1$3
Service cost$24$6$7$1$—$2
Interest cost359121—4
Expected return on plan assets(76)(30)(26)(1)1(10)
Net amortization2—2——6
Net periodic postretirement benefit cost (income)$(15)$(15)$(5)$1$1$2

The service cost component of net periodic postretirement benefit cost is included in operations and maintenance expenses and all other components of net periodic postretirement benefit cost are included in other income (expense), net in the Registrants' statements of income.

The Registrants' future benefit payments, including prescription drug benefits, are provided in the table below. These amounts reflect expected future service and are estimated based on assumptions used to measure the APBO for the other postretirement benefit plans.

Southern Company · Alabama Power · GeorgiaPower · Mississippi Power · Southern Power · Southern Company Gas
(in millions)
Benefit payments:
2024$111$24$40$5$1$17
202510924395117
202610824385116
202710824385116
202810825384115
2029 to 203352312318821164

II-214

Benefit Plan Assets

Pension plan and other postretirement benefit plan assets are managed and invested in accordance with all applicable requirements, including ERISA and the Internal Revenue Code. The Registrants' investment policies for both the pension plans and the other postretirement benefit plans cover a diversified mix of assets as described below. Derivative instruments may be used to gain efficient exposure to the various asset classes and as hedging tools. Additionally, the Registrants minimize the risk of large losses primarily through diversification but also monitor and manage other aspects of risk.

The investment strategy for plan assets related to the Southern Company system's qualified pension plan is to be broadly diversified across major asset classes. The asset allocation is established after consideration of various factors that affect the assets and liabilities of the pension plan including, but not limited to, historical and expected returns and interest rates, volatility, correlations of asset classes, the current level of assets and liabilities, and the assumed growth in assets and liabilities. Because a significant portion of the liability of the pension plan is long-term in nature, the assets are invested consistent with long-term investment expectations for return and risk. To manage the actual asset class exposures relative to the target asset allocation, the Southern Company system employs a formal rebalancing program. As additional risk management, external investment managers and service providers are subject to written guidelines to ensure appropriate and prudent investment practices. Management believes the portfolio is well-diversified with no significant concentrations of risk.

II-215

Investment Strategies and Benefit Plan Asset Fair Values

A description of the major asset classes that the pension and other postretirement benefit plans are comprised of, along with the valuation methods used for fair value measurement, is provided below:

DescriptionValuation Methodology
Domestic equity: A mix of large and small capitalization stocks with generally an equal distribution of value and growth attributes, managed both actively and through passive index approaches.International equity: A mix of large and small capitalization growth and value stocks with developed and emerging markets exposure, managed both actively and through fundamental indexing approaches.Domestic and international equities such as common stocks, American depositary receipts, and real estate investment trusts that trade on public exchanges are classified as Level 1 investments and are valued at the closing price in the active market. Equity funds with unpublished prices that are comprised of publicly traded securities (such as commingled/pooled funds) are also valued at the closing price in the active market, but are classified as Level 2.
Fixed income: A mix of domestic and international bonds.Investments in fixed income securities, including fixed income pooled funds, are generally classified as Level 2 investments and are valued based on prices reported in the market place. Additionally, the value of fixed income securities takes into consideration certain items such as broker quotes, spreads, yield curves, interest rates, and discount rates that apply to the term of a specific instrument.
Trust-owned life insurance (TOLI): Investments of taxable trusts aimed at minimizing the impact of taxes on the portfolio.Investments in TOLI policies are classified as Level 2 investments and are valued based on the underlying investments held in the policy's separate accounts. The underlying assets are equity and fixed income pooled funds that are comprised of Level 1 and Level 2 securities.
Real estate: Investments in equity or debt of real properties and in publicly traded real estate securities.Special situations: Investments in opportunistic strategies with the objective of diversifying and enhancing returns and exploiting short-term inefficiencies, as well as investments in promising new strategies of a longer-term nature.Private equity: Investments in private or public securities typically through privately-negotiated and/or structured transactions, including leveraged buyouts, venture capital, and distressed debt. Private credit: Investments focused on debt instruments, of which returns are driven by income rather than capital appreciation.Infrastructure: Investments in real assets, typically with long-term, predictable, and stable cash flows and a meaningful income component.Investments in real estate, special situations, private equity, private credit, and infrastructure are typically invested in private partnerships and/or other pooled vehicles (Funds) which are generally classified as Net Asset Value as a Practical Expedient, since the Funds and underlying assets are not publicly traded and/or often have liquidity restrictions. The managers of the Funds value the assets using various inputs and techniques depending on the nature of the underlying investments. Techniques may include purchase multiples for comparable transactions, comparable public company trading multiples, discounted cash flow analysis, prevailing market capitalization rates, recent sales of comparable investments, and independent third-party appraisals. The total market value of each of the Funds is determined by aggregating the value of the underlying assets less liabilities.

For purposes of determining the fair value of the pension plan and other postretirement benefit plan assets and the appropriate level designation, management relies on information provided by the plan's trustee. This information is reviewed and evaluated by management with changes made to the trustee information as appropriate. The fair values presented herein exclude cash, receivables related to investment income and pending investment sales, and payables related to pending investment purchases.

The fair values, and actual allocations relative to the target allocations, of the Southern Company system's pension plans at December 31, 2023 and 2022 are presented below.

II-216

Fair Value Measurements Using
Quoted Prices in Active Markets for Identical Assets · SignificantOtherObservableInputs · SignificantUnobservableInputs · Net Asset Value as a Practical Expedient · Target Allocation · Actual Allocation
At December 31, 2023: · (Level 1) · (Level 2) · (Level 3) · (NAV) · Total
(in millions)
Southern Company
Assets:
Equity:41%40%
Domestic equity$1,959$771$—$—$2,730
International equity1,9471,052——2,999
Fixed income:3032
U.S. Treasury, government, and agency bonds—1,973——1,973
Mortgage- and asset-backed securities—44——44
Corporate bonds—1,724——1,724
Pooled funds—777——777
Cash equivalents and other37158——429
Real estate investments369——1,6842,0531214
Special situations———24524532
Private equity———1,7611,761912
Private credit———25253—
Infrastructure—————2—
Total$4,646$6,399$—$3,715$14,760100%100%
Alabama Power
Assets:
Equity:41%40%
Domestic equity$476$187$—$—$663
International equity472255——727
Fixed income:3032
U.S. Treasury, government, and agency bonds—479——479
Mortgage- and asset-backed securities—11——11
Corporate bonds—418——418
Pooled funds—188——188
Cash equivalents and other9014——104
Real estate investments89——4084971214
Special situations———595932
Private equity———427427912
Private credit———663—
Infrastructure—————2—
Total$1,127$1,552$—$900$3,579100%100%

II-217

Fair Value Measurements Using
Quoted Prices in Active Markets for Identical Assets · SignificantOtherObservableInputs · SignificantUnobservableInputs · Net Asset Value as a Practical Expedient · Target Allocation · Actual Allocation
At December 31, 2023: · (Level 1) · (Level 2) · (Level 3) · (NAV) · Total
(in millions)
Georgia Power
Assets:
Equity:41%40%
Domestic equity$611$241$—$—$852
International equity609329——938
Fixed income:3032
U.S. Treasury, government, and agency bonds—617——617
Mortgage- and asset-backed securities—14——14
Corporate bonds—539——539
Pooled funds—243——243
Cash equivalents and other11618——134
Real estate investments115——5276421214
Special situations———777732
Private equity———551551912
Private credit———883—
Infrastructure—————2—
Total$1,451$2,001$—$1,163$4,615100%100%
Mississippi Power
Assets:
Equity:41%40%
Domestic equity$89$35$—$—$124
International equity8948——137
Fixed income:3032
U.S. Treasury, government, and agency bonds—90——90
Mortgage- and asset-backed securities—2——2
Corporate bonds—79——79
Pooled funds—36——36
Cash equivalents and other173——20
Real estate investments17——77941214
Special situations———111132
Private equity———8181912
Private credit———113—
Infrastructure—————2—
Total$212$293$—$170$675100%100%

II-218

Fair Value Measurements Using
Quoted Prices in Active Markets for Identical Assets · SignificantOtherObservableInputs · SignificantUnobservableInputs · Net Asset Value as a Practical Expedient · Target Allocation · Actual Allocation
At December 31, 2023: · (Level 1) · (Level 2) · (Level 3) · (NAV) · Total
(in millions)
Southern Power
Assets:
Equity:41%40%
Domestic equity$24$10$—$—$34
International equity2513——38
Fixed income:3032
U.S. Treasury, government, and agency bonds—25——25
Mortgage- and asset-backed securities—1——1
Corporate bonds—22——22
Pooled funds—10——10
Cash equivalents and other51——6
Real estate investments5——21261214
Special situations———3332
Private equity———2222912
Private credit—————3—
Infrastructure—————2—
Total$59$82$—$46$187100%100%
Southern Company Gas
Assets:
Equity:41%40%
Domestic equity$130$52$—$—$182
International equity13071——201
Fixed income:3032
U.S. Treasury, government, and agency bonds—132——132
Mortgage- and asset-backed securities—3——3
Corporate bonds—116——116
Pooled funds—52——52
Cash equivalents and other254——29
Real estate investments25——1131381214
Special situations———161632
Private equity———118118912
Private credit———223—
Infrastructure—————2—
Total$310$430$—$249$989100%100%

II-219

Fair Value Measurements Using
Quoted Prices in Active Markets for Identical Assets · SignificantOtherObservableInputs · SignificantUnobservableInputs · Net Asset Value as a Practical Expedient · Target Allocation · Actual Allocation
At December 31, 2022: · (Level 1) · (Level 2) · (Level 3) · (NAV) · Total
(in millions)
Southern Company
Assets:
Equity:45%43%
Domestic equity$2,078$691$—$—$2,769
International equity2,1661,090——3,256
Fixed income:3028
U.S. Treasury, government, and agency bonds—1,469——1,469
Mortgage- and asset-backed securities—29——29
Corporate bonds—1,494——1,494
Pooled funds—607——607
Cash equivalents and other3997——406
Real estate investments376——1,8872,2631315
Special situations———18718732
Private equity———1,7171,717912
Total$5,019$5,387$—$3,791$14,197100%100%
Liabilities:
Derivatives(4)———(4)
Total$5,015$5,387$—$3,791$14,193100%100%
Alabama Power
Assets:
Equity:45%43%
Domestic equity$500$167$—$—$667
International equity522263——785
Fixed income:3028
U.S. Treasury, government, and agency bonds—354——354
Mortgage- and asset-backed securities—7——7
Corporate bonds—360——360
Pooled funds—146——146
Cash equivalents and other962——98
Real estate investments91——4555461315
Special situations———454532
Private equity———414414912
Total$1,209$1,299$—$914$3,422100%100%
Liabilities:
Derivatives(1)———(1)
Total$1,208$1,299$—$914$3,421100%100%

II-220

Fair Value Measurements Using
Quoted Prices in Active Markets for Identical Assets · SignificantOtherObservableInputs · SignificantUnobservableInputs · Net Asset Value as a Practical Expedient · Target Allocation · Actual Allocation
At December 31, 2022: · (Level 1) · (Level 2) · (Level 3) · (NAV) · Total
(in millions)
Georgia Power
Assets:
Equity:45%43%
Domestic equity$651$217$—$—$868
International equity678342——1,020
Fixed income:3028
U.S. Treasury, government, and agency bonds—460——460
Mortgage- and asset-backed securities—9——9
Corporate bonds—468——468
Pooled funds—190——190
Cash equivalents and other1252——127
Real estate investments118——5917091315
Special situations———595932
Private equity———538538912
Total$1,572$1,688$—$1,188$4,448100%100%
Liabilities:
Derivatives(1)———(1)
Total$1,571$1,688$—$1,188$4,447100%100%
Mississippi Power
Assets:
Equity:45%43%
Domestic equity$95$32$—$—$127
International equity9950——149
Fixed income:3028
U.S. Treasury, government, and agency bonds—67——67
Mortgage- and asset-backed securities—1——1
Corporate bonds—68——68
Pooled funds—28——28
Cash equivalents and other18———18
Real estate investments17——861031315
Special situations———9932
Private equity———7878912
Total$229$246$—$173$648100%100%

II-221

Fair Value Measurements Using
Quoted Prices in Active Markets for Identical Assets · SignificantOtherObservableInputs · SignificantUnobservableInputs · Net Asset Value as a Practical Expedient · Target Allocation · Actual Allocation
At December 31, 2022: · (Level 1) · (Level 2) · (Level 3) · (NAV) · Total
(in millions)
Southern Power
Assets:
Equity:45%43%
Domestic equity$25$9$—$—$34
International equity2714——41
Fixed income:3028
U.S. Treasury, government, and agency bonds—18——18
Corporate bonds—19——19
Pooled funds—8——8
Cash equivalents and other5———5
Real estate investments5——24291315
Special situations———2232
Private equity———2121912
Total$62$68$—$47$177100%100%
Southern Company Gas
Assets:
Equity:45%43%
Domestic equity$146$49$—$—$195
International equity15277——229
Fixed income:3028
U.S. Treasury, government, and agency bonds—104——104
Mortgage- and asset-backed securities—2——2
Corporate bonds—105——105
Pooled funds—43——43
Cash equivalents and other281——29
Real estate investments27——1331601315
Special situations———131332
Private equity———121121912
Total$353$381$—$267$1,001100%100%

II-222

The fair values, and actual allocations relative to the target allocations, of the applicable Registrants' other postretirement benefit plan assets at December 31, 2023 and 2022 are presented below.

Fair Value Measurements Using
Quoted Prices in Active Markets for Identical AssetsSignificantOtherObservableInputsNet Asset Value as a Practical ExpedientTotalTarget AllocationActual Allocation
At December 31, 2023: · (Level 1) · (Level 2) · (NAV)
(in millions)
Southern Company
Assets:
Equity:60%61%
Domestic equity$85$87$—$172
International equity5382—135
Fixed income:3028
U.S. Treasury, government, and agency bonds—57—57
Mortgage- and asset-backed securities—2—2
Corporate bonds—47—47
Pooled funds—92—92
Cash equivalents and other212—23
Trust-owned life insurance—456—456
Real estate investments11—465746
Special situations——6611
Private equity——484834
Private credit——111—
Infrastructure————1—
Total$170$825$101$1,096100%100%
Alabama Power
Assets:
Equity:67%66%
Domestic equity$16$6$—$22
International equity169—25
Fixed income:2323
U.S. Treasury, government, and agency bonds—16—16
Corporate bonds—14—14
Pooled funds—8—8
Cash equivalents and other3——3
Trust-owned life insurance—280—280
Real estate investments3—141746
Special situations——2211
Private equity——151534
Private credit————1—
Infrastructure————1—
Total$38$333$31$402100%100%

II-223

Fair Value Measurements Using
Quoted Prices in Active Markets for Identical AssetsSignificantOtherObservableInputsNet Asset Value as a Practical ExpedientTotalTarget AllocationActual Allocation
At December 31, 2023: · (Level 1) · (Level 2) · (NAV)
(in millions)
Georgia Power
Assets:
Equity:58%57%
Domestic equity$47$6$—$53
International equity1640—56
Fixed income:3535
U.S. Treasury, government, and agency bonds—16—16
Corporate bonds—14—14
Pooled funds—47—47
Cash equivalents and other13——13
Trust-owned life insurance—176—176
Real estate investments4—141834
Special situations——2211
Private equity——141423
Private credit————1—
Infrastructure——————
Total$80$299$30$409100%100%
Mississippi Power
Assets:
Equity:34%33%
Domestic equity$3$1$—$4
International equity31—4
Fixed income:4344
U.S. Treasury, government, and agency bonds—7—7
Corporate bonds—2—2
Pooled funds—1—1
Cash equivalents and other1——1
Real estate investments1—231011
Special situations————22
Private equity——22710
Private credit————3—
Infrastructure————1—
Total$8$12$4$24100%100%

II-224

Fair Value Measurements Using
Quoted Prices in Active Markets for Identical AssetsSignificantOtherObservableInputsNet Asset Value as a Practical ExpedientTotalTarget AllocationActual Allocation
At December 31, 2023: · (Level 1) · (Level 2) · (NAV)
(in millions)
Southern Company Gas
Assets:
Equity:72%72%
Domestic equity$2$67$—$69
International equity222—24
Fixed income:2626
U.S. Treasury, government, and agency bonds—1—1
Corporate bonds—1—1
Pooled funds—29—29
Cash equivalents and other1——1
Trust-owned life insurance————
Real estate investments——1111
Private equity——1111
Total$5$120$2$127100%100%

II-225

Fair Value Measurements Using
Quoted Prices in Active Markets for Identical Assets · SignificantOtherObservableInputs · Net Asset Value as a Practical Expedient · Target Allocation · Actual Allocation
At December 31, 2022: · (Level 1) · (Level 2) · (NAV) · Total
(in millions)
Southern Company
Assets:
Equity:61%59%
Domestic equity$85$74$—$159
International equity5879—137
Fixed income:3028
U.S. Treasury, government, and agency bonds—43—43
Mortgage- and asset-backed securities—1—1
Corporate bonds—40—40
Pooled funds—79—79
Cash equivalents and other19——19
Trust-owned life insurance—406—406
Real estate investments11—516257
Special situations——6611
Private equity——464635
Total$173$722$103$998100%100%
Alabama Power
Assets:
Equity:69%65%
Domestic equity$17$6$—$23
International equity189—27
Fixed income:2323
U.S. Treasury, government, and agency bonds—12—12
Corporate bonds—12—12
Pooled funds—7—7
Cash equivalents and other3——3
Trust-owned life insurance—252—252
Real estate investments3—161947
Special situations——2211
Private equity——141434
Total$41$298$32$371100%100%

II-226

Fair Value Measurements Using
Quoted Prices in Active Markets for Identical Assets · SignificantOtherObservableInputs · Net Asset Value as a Practical Expedient · Target Allocation · Actual Allocation
At December 31, 2022: · (Level 1) · (Level 2) · (NAV) · Total
(in millions)
Georgia Power
Assets:
Equity:58%56%
Domestic equity$46$6$—$52
International equity1739—56
Fixed income:3534
U.S. Treasury, government, and agency bonds—10—10
Corporate bonds—12—12
Pooled funds—40—40
Cash equivalents and other9——9
Trust-owned life insurance—154—154
Real estate investments4—151945
Special situations——2211
Private equity——141424
Total$76$261$31$368100%100%
Mississippi Power
Assets:
Equity:37%35%
Domestic equity$3$1$—$4
International equity32—5
Fixed income:4341
U.S. Treasury, government, and agency bonds—4—4
Corporate bonds—2—2
Pooled funds—1—1
Cash equivalents and other2——2
Real estate investments1—341112
Special situations————22
Private equity——22710
Total$9$10$5$24100%100%

II-227

Fair Value Measurements Using
Quoted Prices in Active Markets for Identical Assets · SignificantOtherObservableInputs · Net Asset Value as a Practical Expedient · Target Allocation · Actual Allocation
At December 31, 2022: · (Level 1) · (Level 2) · (NAV) · Total
(in millions)
Southern Company Gas
Assets:
Equity:72%70%
Domestic equity$2$56$—$58
International equity220—22
Fixed income:2627
U.S. Treasury, government, and agency bonds—1—1
Corporate bonds—1—1
Pooled funds—27—27
Cash equivalents and other1——1
Real estate investments——2212
Private equity——1111
Total$5$105$3$113100%100%

Employee Savings Plan

Southern Company and its subsidiaries also sponsor 401(k) defined contribution plans covering substantially all employees and provide matching contributions up to specified percentages of an employee's eligible pay. Total matching contributions made to the plans for 2023, 2022, and 2021 were as follows:

Southern Company · AlabamaPower · GeorgiaPower · MississippiPower · SouthernPower · Southern Company Gas
(in millions)
2023$131$28$31$5$3$18
202212426295317
202111926285216
ContentsView on SEC.gov

The text of this filing, as the company filed it with the SEC, without its images or exhibits. This is not investment advice.