AMEREN CORP

RESULTS OF OPERATIONS

Our results of operations and financial position are affected by many factors. Economic conditions, energy-efficiency investments by our customers and by us, technological advances, distributed generation, and the actions of key customers can significantly affect the demand for our services. Ameren and Ameren Missouri results are also affected by seasonal fluctuations in winter heating and summer cooling demands and by weather conditions, such as storms, as well as by energy center maintenance outages. Additionally, fluctuations in interest rates and conditions in the capital and credit markets affect our cost of borrowing, our pension and postretirement benefits costs, the cash surrender value of COLI, and the asset value of Ameren Missouri’s nuclear decommissioning trust fund. Almost all of Ameren’s revenues are subject to state or federal regulation. This regulation has a material impact on the rates we charge customers for our services. Our results of operations, financial position, and liquidity are affected by our ability to align our overall spending, both operating and capital, with the frameworks established by our regulators. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for additional information regarding Ameren Missouri’s, Ameren Illinois’, and ATXI’s regulatory frameworks.

Ameren Missouri principally uses coal and enriched uranium for fuel in its electric operations and purchases natural gas for its customers. Ameren Illinois purchases power and natural gas for its customers. The prices for these commodities can fluctuate significantly because of the global economic and political environment, weather, supply, demand, inflation, and many other factors. We have natural gas cost recovery mechanisms for our Illinois and Missouri natural gas distribution businesses, a purchased power cost recovery mechanism for Ameren Illinois’ electric distribution business, and a FAC for Ameren Missouri’s electric business.

We employ various risk management strategies to reduce our exposure to commodity risk and other risks inherent in our business. The reliability of Ameren Missouri’s energy centers and our transmission and distribution systems and the level and timing of operations and maintenance costs and capital investment are key factors that we seek to manage in order to optimize our results of operations, financial position, and liquidity.

Earnings Summary

The following table presents a summary of Ameren’s earnings for the years ended December 31, 2024 and 2023:

Net income attributable to Ameren common shareholders in 2024 increased $30 million, and $0.04 per diluted share, from 2023. The increase was due to net income increases of $27 million, $15 million, and $14 million at Ameren Transmission, Ameren Illinois Natural Gas, and Ameren Missouri, respectively. The increases in net income were partially offset by a net income decrease of $24 million at Ameren Illinois Electric Distribution and an increase in the net loss for activity not reported as part of a segment, primarily at Ameren (parent), of $2 million.

Earnings per share in 2024, compared with 2023, were favorably affected by:

•increased allowance for equity funds used during construction and increased base rate revenues for the inclusion of previously deferred PISA and RESRAM interest charges pursuant to the June 2023 MoPSC electric rate order effective July 9, 2023, and decreased interest charges resulting from higher deferrals related to infrastructure investments associated with the PISA and RESRAM, at Ameren Missouri (17 cents per share);

•increased rate base investments at Ameren Transmission, which increased earnings in this segment (16 cents per share);

•increased base rate revenues at Ameren Missouri effective July 9, 2023, pursuant to the June 2023 MoPSC electric rate order, partially offset by the net effect of amortization of previously deferred depreciation expense under the PISA and RESRAM, financing costs otherwise recoverable under the PISA and RESRAM, a lower base level of expenses included in trackers, and the net recovery for amounts associated with the reduction in sales volumes resulting from MEEIA programs (9 cents per share);

•increased retail electric sales volumes at Ameren Missouri, primarily due to higher sales excluding customer energy-efficiency programs (estimated at 8 cents per share);

•increased other income, net, primarily due to lower donations and a gain on the extinguishment of debt, see Note 5 – Long-term Debt and Equity Financings under Part II, Item 8, of this report for more information, partially offset by decreased non-service cost components of net periodic benefit income not subject to formula rates or trackers largely due to lower investment returns (6 cents per share);

•increased base rate revenues at Ameren Illinois Natural Gas effective November 28, 2023, pursuant to the November 2023 ICC natural gas rate order, partially offset by increased depreciation and amortization expenses included in base rates (4 cents per share); and

•decreased other operations and maintenance expenses not subject to formula rates, riders, or trackers, excluding a charge related to the NSR and Clean Air Act litigation discussed below largely because of lower energy center maintenance costs, lower storm costs, disciplined cost management including lower labor costs from decreased headcount and decreased use of contractors, and lower amortization of refueling costs for the Callaway Energy Center, partially offset by the absence of regulatory deferrals associated with the June 2023 MoPSC rate order (2 cents per share).

Earnings per share in 2024, compared with 2023, were unfavorably affected by:

•a charge recorded by Ameren Missouri, included in other operation and maintenance expenses, related to an order from the United States District Court for the Eastern District of Missouri, which resolved all outstanding claims in the NSR and Clean Air Act litigation related to the Rush Island Energy Center, see Note 14 - Commitments and Contingencies under Part II, Item 8, of this report for more information (17 cents per share);

•increased financing costs primarily at Ameren Missouri and Ameren (parent), largely due to higher long-term debt balances and interest rates, partially offset by lower levels of short-term borrowings (17 cents per share);

•lower revenue at Ameren Illinois Electric Distribution due to a lower recognized ROE under the MYRP (9 cents per share);

•increased weighted-average basic common shares outstanding resulting from issuances of common shares (7 cents per share);

•the result of the October 2024 FERC order reducing the allowed base ROE for FERC regulated transmission rate base under the MISO tariff, which decreased Ameren Transmission earnings (4 cents per share); and

•increased taxes other than income taxes at Ameren Missouri, largely resulting from the absence in 2024 of employee retention tax credits received under the Coronavirus Aid, Relief, and Economic Security Act (2 cents per share).

The cents per share variances above are presented based on the weighted-average basic shares outstanding in 2023 and do not reflect the impact of dilution on earnings per share, unless otherwise noted. The amounts above other than variances related to income taxes have been presented net of income taxes using Ameren’s 2024 blended federal and state statutory tax rate of 26%. For additional details regarding the Ameren Companies’ results of operations, including explanations of Operating Revenues for both Electric Revenues and Natural Gas Revenues; Fuel and Purchased Power Expenses; Other Operations and Maintenance Expenses; Depreciation and Amortization Expenses; Taxes Other Than Income Taxes; Other Income, Net; Interest Charges; and Income Taxes, see the major headings below.

Below is Ameren’s table of income statement components by segment for the years ended December 31, 2024 and 2023:

Below is Ameren Illinois’ table of income statement components by segment for the years ended December 31, 2024 and 2023:

Operating Revenues

The following table presents the increases (decreases) by Ameren segment for electric and natural gas revenues in 2024, compared with 2023:

(a)Includes an increase in transmission revenues of $84 million in 2024, compared with 2023, at Ameren Illinois.

(b)For Ameren Illinois Electric Distribution and Ameren Transmission, base rates include increases or decreases in operating revenues related to the revenue requirement reconciliation adjustment under the MYRP and formula rates, respectively. For Ameren Missouri, base rates exclude an increase for the recovery of lost electric revenue, less the associated fuel and purchased power expenses, resulting from the MEEIA customer energy-efficiency programs and a decrease in base rates for RESRAM. These changes in Ameren Missouri base rates are included in the “Retail sales volumes and changes in customer usage patterns (excluding the estimated effects of weather and MEEIA)” and “Cost recovery mechanisms - offset in fuel and purchased power” line items, respectively.

(c)Represents the estimated variation resulting primarily from changes in cooling and heating degree-days on electric and natural gas demand compared with the prior year; this variation is based on temperature readings from National Oceanic and Atmospheric Administration weather stations at local airports in our service territories.

(d)The electric deferred income tax adjustment relates to certain excess deferred income taxes that will be amortized through 2025. Offsetting expense increases or decreases are reflected within "Income Taxes" on the statement of income. This item has no overall impact on earnings.

(e)Electric and natural gas revenue changes are offset by corresponding changes in “Fuel and purchased power” and “Natural gas purchased for resale” on the statement of income. Activity in Other/Intersegment Eliminations of $12 million represents the changes in eliminations of related-party transactions between Ameren Missouri, Ameren Illinois, and ATXI (-$6 million), as well as changes in Ameren Transmission revenue from transmission services provided to Ameren Illinois Electric Distribution

(-$6 million). See Note 13 – Related-party Transactions and Note 16 – Segment Information under Part II, Item 8, of this report for additional information on intersegment eliminations. These items have no overall impact on earnings.

(f)Offsetting expense increases or decreases are reflected in “Other operations and maintenance,” “Depreciation and amortization,” or in “Taxes other than income taxes,” within “Operating Expenses” on the statement of income. These items have no overall impact on earnings.

Electric Revenues

Ameren

Ameren’s electric revenues increased $101 million, or 2%, in 2024, compared with 2023, due to increased revenues at Ameren Missouri and Ameren Transmission, partially offset by decreased revenues at Ameren Illinois Electric Distribution, as discussed below.

Ameren Transmission’s electric revenues increased $104 million, or 15%, in 2024, compared with 2023. Revenues were favorably affected by higher recoverable expenses (+$55 million), increased capital investment (+$44 million), as evidenced by a 15% increase in rate base used to calculate the revenue requirement, and increased facility rental revenues (+$15 million) related to ATXI’s transmission operations control center, which was placed in service in December 2023. ATXI provides affiliates with access to this facility. Rental revenues associated with this facility are affiliate transactions and eliminated in consolidation for Ameren’s consolidated financial statements. See Note 13 – Related-party Transactions under Part II, Item 8, of this report for additional information. Revenues were unfavorably affected by a decrease in the allowed base ROE under the MISO tariff resulting from the October 2024 FERC order, which included customer refunds for certain historical periods (-$10 million). See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for additional information regarding the FERC complaint cases.

Ameren Missouri’s electric revenues increased $153 million, or 4%, in 2024, compared with 2023.

The following items had a favorable effect on Ameren Missouri’s electric revenues in 2024, compared with 2023:

•“Off-system sales, capacity, transmission, and FAC revenues, net” increased $96 million, primarily due to higher summer and fall capacity prices which were set by annual MISO auctions.

•Higher electric base rates, resulting from the June 2023 MoPSC electric rate order effective July 9, 2023, increased revenues an estimated$62 million.

•Excluding the estimated effects of weather and the MEEIA customer energy-efficiency programs, electric revenues increased an estimated$27 million, due to an increase in residential customer counts, retail sales volumes from large commercial and industrial customers, the absence of customer outages resulting from major storms experienced throughout the service territory in July and August 2023, and an additional day in 2024 as a result of the leap year. The increase is partially offset by lower realized prices due to changes in customer usage patterns and economic development discounts.

•Revenues associated with other cost recovery mechanisms increased $22 million, primarily due to an increase in RESRAM revenues and an increase in excise taxes due to increased retail sales revenue.

•Other revenues increased $6 million due to pole rents (+$2 million), other rentals (+$2 million), and other miscellaneous revenues

(+$2 million).

•The aggregate effect of weather increased revenues an estimated $3 million as cooling degree days increased 7% and heating degree days decreased 4%.

The following items had an unfavorable effect on Ameren Missouri’s electric revenues in 2024, compared with 2023:

•Revenues associated with “Cost recovery mechanisms – offset in fuel and purchased power” decreased $54 million, due to decreased revenue related to the amortization of costs previously deferred under the FAC that were reflected in customer rates. The changes to “Cost recovery mechanisms - offset in fuel and purchased power” are fully offset by changes to “Cost recovery mechanisms - offset in electric revenue” in fuel and purchased power.

•In accordance with the June 2024 MoPSC financing order, revenues decreased $13 million due to the deferral of base rate revenues to a regulatory liability related to the Rush Island Energy Center since its October 15, 2024 retirement date. The regulatory liability will be refunded to customers in a future rate proceeding.

Ameren Illinois’ electric revenues decreased $51 million, or 2%, in 2024, compared with 2023, driven by decreased revenues at Ameren Illinois Electric Distribution, partially offset by increased revenues at Ameren Illinois Transmission.

Ameren Illinois Electric Distribution’s revenues decreased $129 million, or 6%, in 2024, compared with 2023.

The following items had an unfavorable effect on Ameren Illinois Electric Distribution’s revenues in 2024, compared with 2023:

•Revenues associated with “Cost recovery mechanisms – offset in fuel and purchased power” decreased $193 million, due to decreased purchased power expenses recovered from customers. The decreases in electric revenues are fully offset by decreases in purchased power expenses under cost recovery mechanisms for purchased power, as discussed below.

•Pursuant to an ICC order, revenues decreased $23 million, due to an increase in the amortization rate for certain excess deferred income taxes.

The following items had a favorable effect on Ameren Illinois Electric Distribution’s revenues in 2024, compared with 2023:

•Other cost recovery mechanisms increased revenues by $45 million, primarily due to a higher amount of bad debt and purchased receivables from alternative retail electric suppliers included in customer rates pursuant to their associated riders, partially offset by lower environmental remediation revenues.

•Revenues associated with customer energy-efficiency program investments increased $21 million, due to the recovery of program expenses (+$15 million), an increase in the ROE (+$4 million) primarily due to maximum achievement of the annual 2023 energy savings goals, and increased investment of $2 million.

•Base rates increased revenues by $14 million, primarily due to higher recoverable non-purchased power expenses (+$38 million), partially offset by a lower recognized ROE (-$24 million). The MYRP utilizes a fixed ROE approved by the ICC of 8.72%, with adjustments for any performance incentives and penalties, while the IEIMA formula-based ROE was based on the annual average of the monthly yields of the 30-year United States Treasury bonds plus 580 basis points (9.84% as of December 31, 2023).

•The recovery of labor and benefit costs for crews assisting other utilities with power restoration efforts, primarily caused by hurricane damage, increased revenues by $3 million.

Ameren Illinois Transmission’s revenues increased$84 million, or 18%, in 2024, compared with 2023. Base rate revenues were favorably affected by higher recoverable expenses (+$58 million) and increased capital investment (+$33 million), as evidenced by a 17% increase in rate base used to calculate the revenue requirement. Base rate revenues were unfavorably affected by a decrease in the allowed base ROE under the MISO tariff resulting from the October 2024 FERC order, which included customer refunds for certain historical periods (-$7 million). See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for additional information regarding the FERC ROE complaint cases.

Natural Gas Revenues

Ameren

Ameren’s natural gas revenues increased$22 million, or 2%, in 2024, compared with 2023, due to increased revenues at Ameren Illinois Natural Gas, partially offset by decreased revenues at Ameren Missouri, as discussed below.

Ameren Missouri’s natural gas revenues decreased $19 million, or 12%, in 2024, compared with 2023. Revenues associated with “Cost recovery mechanisms – offset in natural gas purchased for resale” decreased $20 million in 2024, compared with 2023, due to lower commodity prices and the absence of amortization of natural gas costs deferred under the PGA related to the extremely cold weather in mid-February 2021. Changes in natural gas revenues under the PGA are fully offset by corresponding changes in natural gas purchased for resale expenses.

Ameren Illinois Natural Gas’ revenues increased $41 million, or 5%, in 2024, compared with 2023. Revenues increased an estimated $47 million due to higher natural gas base rates as a result of the November 2023 natural gas rate order, and revenues associated with other cost recovery mechanisms increased $7 million primarily due to increased revenues for excise taxes. “Cost recovery mechanisms – offset in natural gas purchased for resale” decreased revenues $16 million, due to lower collection of natural gas costs previously deferred under the PGA. Changes in natural gas revenues under the PGA are fully offset by the decrease in natural gas purchased for resale expenses.

Fuel and Purchased Power

The following table presents the increases (decreases) by Ameren segment for fuel and purchased power in 2024, compared with 2023:

(a)“Cost recovery mechanisms — offset in electric revenue” changes are offset by corresponding changes in “Cost recovery mechanisms — offset in fuel and purchased power” in electric revenues. Activity in Other/Intersegment Eliminations of $12 million represents the changes in eliminations of related-party transactions between Ameren Missouri, Ameren Illinois, and ATXI (-$6 million), as well as changes in Ameren Transmission revenue from transmission services provided to Ameren Illinois Electric Distribution (-$6 million). See Note 13 – Related-party Transactions and Note 16 – Segment Information under Part II, Item 8, of this report for additional information on intersegment eliminations. These items have no overall impact on earnings.

Ameren

Ameren Missouri and Ameren Illinois are generally allowed to pass on to customers prudently incurred costs for fuel and purchased power. Ameren’s electric fuel and purchased power expenses decreased $131 million, or 7%, in 2024, compared with 2023, primarily due to decreased fuel and purchased power expenses at Ameren Illinois Electric Distribution, partially offset by increased fuel and purchased power expenses at Ameren Missouri, as discussed below.

Ameren Missouri’s fuel and purchased power expenses increased $74 million, or 7%, in 2024, compared with 2023.

The following items increased Ameren Missouri’s fuel and purchased power expense in 2024, compared with 2023:

•Energy costs increased $95 million in 2024, compared with 2023, primarily due to higher summer and fall capacity prices, which were set by annual MISO auctions. Ameren Missouri’s 5% exposure to net energy cost variances under the FAC is the difference between “Off-system sales, capacity, transmission, and FAC revenues, net” and “Energy costs (excluding the estimated effect of weather)”. These results had an immaterial impact on earnings in 2024, compared with 2023.

•The effect of higher net energy costs included in base rates increased Ameren Missouri’s fuel and purchased power expenses $22 million in 2024, compared with 2023, as a result of the June 2023 MoPSC electric rate order.

•Transmission service charges increased $8 million due to higher transmission rates related to increased revenue requirements of other transmission operators.

•Increases in retail sales volumes increased Ameren Missouri’s fuel and purchased power expenses $6 million.

“Cost recovery mechanisms — offset in electric revenue” decreased $54 million in 2024, compared with 2023, due to decreased amortization of costs previously deferred under the FAC. The changes to “Cost recovery mechanisms - offset in electric revenue” are fully offset by “Cost recovery mechanisms - offset in fuel and purchased power” in electric revenues.

Ameren Illinois Electric Distribution’s purchased power expenses decreased $193 million, or 21%, in 2024, compared with 2023, primarily due to decreased energy prices (-$94 million), which largely reflect the results of IPA procurement events, decreased capacity prices (-$77 million), which were set by annual MISO auctions, and lower volumes (-$43 million) primarily due to residential and small commercial customers switching from Ameren Illinois’ supplied power to alternative retail electric suppliers and customer adoption of solar technology through initiatives required under Illinois law. These decreases in purchased power expenses were partially offset by increased expenses associated with the amortization of renewable energy credit costs (+$20 million). The changes to “Cost recovery mechanisms - offset in electric revenue” are fully offset by changes to “Cost recovery mechanisms - offset in fuel and purchased power” in electric revenues.

Natural Gas Purchased for Resale

The following table presents the increases (decreases) by Ameren segment for natural gas purchased for resale in 2024, compared with 2023:

(a)Represents the estimated variation resulting primarily from changes in heating degree-days on natural gas demand compared with the prior year; this variation is based on temperature readings from the National Oceanic and Atmospheric Administration weather stations at local airports in our service territories.

(b)Natural gas purchased for resale changes are offset by corresponding changes in “Natural gas revenues” on the statement of income. These items have no overall impact on earnings.

Ameren

Ameren Missouri and Ameren Illinois are allowed to pass on to customers prudently incurred costs for natural gas purchased for resale. Ameren’s natural gas purchased for resale expenses decreased $35 million, or 10%, in 2024, compared with 2023, due to decreased natural gas purchased for resale expenses at Ameren Missouri and Ameren Illinois Natural Gas, as discussed below.

Ameren Missouri’s natural gas purchased for resale expenses decreased $19 million, or 24%, in 2024, compared with 2023. Expenses associated with “Cost recovery mechanisms – offset in natural gas revenue” decreased $20 million in 2024, compared with 2023, due tolower commodity prices and the absence of amortization of natural gas costs deferred under the PGA related to the extremely cold weather in mid-February 2021. Changes in natural gas purchased for resale expenses are fully offset by corresponding changes in natural gas revenues under the PGA.

Ameren Illinois Natural Gas’ natural gas purchased for resale expenses decreased $16 million, or 6%, in 2024, compared with 2023, primarily due to lower amortization of natural gas costs that were previously deferred under the PGA and lower natural gas prices. Changes in natural gas purchased for resale expenses are fully offset by changes in natural gas revenues under the PGA.

Other Operations and Maintenance Expenses

(a)Includes $70 million and $60 million at Ameren Transmission in 2024 and 2023, respectively, and other/intersegment eliminations of $0 million and $34 million in 2024 and 2023, respectively.

Ameren

Other operations and maintenance expenses increased $103 million in 2024, compared with 2023 because of the changes discussed below. In addition to changes by segment as discussed below, other operations and maintenance expenses decreased $34 million in 2024 for activity not reported as part of a segment, as reflected in “Other/Intersegment Eliminations” above, primarily because of a $14 million increase in the elimination of intercompany rent related to ATXI’s operations control center discussed below; a $10 million increase in the elimination of the non-service cost component of net periodic benefit income at Ameren Services; and a $8 million gain on the sale of land. The non-service cost component of net periodic benefit cost or income at Ameren Services is allocated to the segments and primarily included in the segments’ other operations and maintenance expenses.

Other operations and maintenance expenses increased $10 million in 2024, compared with 2023, primarily because of increased costs related to ATXI’s operations control center, which was placed in service in December 2023. ATXI provides affiliates with access to this facility. The rent expense associated with this facility is an affiliate transaction and eliminated in consolidation for purposes of Ameren’s consolidated financial statements. See Note 13 - Related-party Transactions under Part II, Item 8, of this report for additional information.

Other operations and maintenance expenses increased $47 million in 2024, compared with 2023, primarily due to the following items:

•A $59 million charge related to an order from the United States District Court for the Eastern District of Missouri, which resolved all outstanding claims in the NSR and Clean Air Act litigation related to the Rush Island Energy Center, see Note 14 - Commitments and Contingencies under Part II, Item 8, of this report for more information.

•The absence in 2024 of the recognition of regulatory assets for previously expensed costs approved for recovery pursuant to the June 2023 MoPSC rate order increased expenses $15 million.

•Individually insignificant increases of $7 million in various other operations and maintenance expenses, including other labor, cloud computing costs, and a decrease in the cash surrender value of COLI.

•The absence of previously deferred expenses increased expense by $7 million.

•Legal and administrative expenses increased by $6 million, primarily related to environmental matters.

•Costs for injuries and damages increased $4 million, primarily due to an increase in claims.

•Renewable development costs increased $3 million, primarily due to the absence in 2024 of the MoPSC order approving CCNs for the Boomtown and Huck Finn energy centers in the first half of 2023 that led to increased capitalization of renewable development costs pursuant to anticipated recovery from customers.

The following items partially offset the above increases in other operations and maintenance expenses between years:

•Pension and benefit costs decreased $20 million because of a lower base level of expenses, subject to a tracker, included in customer rates pursuant to the June 2023 MoPSC electric rate order. See Note 10 - Retirement Benefits under Part II, Item 8, of this report for more information.

•Energy center maintenance decreased $17 million, primarily because of lower amortization of Callaway Energy Center refueling and maintenance costs resulting from cost saving initiatives in the fall 2023 outage, compared to the spring 2022 outage, and lower headcount.

•Transmission and distribution storm-related costs decreased $10 million because of the major storms experienced throughout the service territory in July and August 2023.

•Transmission and distribution expenditures, excluding major storm-related costs, decreased $8 million, primarily due to reduced levels of vegetation management expenditures and lower inspection costs from decreased use of contractors, and lower headcount.

Other operations and maintenance expenses increased $88 million at Ameren Illinois in 2024, compared with 2023, as discussed below.

Other operations and maintenance increased $87 million in 2024, compared with 2023, was primarily due to the following items:

•Bad debt costs increased $52 million, primarily because of a higher base level of expenses included in customer rates pursuant to the associated rider.

•Amortization of previous deferrals associated with bad debt costs on purchased receivables increased $15 million, primarily because of a higher base level of expenses included in customer rates pursuant to the associated rider.

•Increased costs associated with customer energy-efficiency investments under formula ratemaking of $13 million, primarily due to amortization of regulatory assets.

•Benefit costs increased $6 million, primarily due to an increase in medical benefit claims related to active plan participants.

•Increased labor expense of $5 million, primarily caused by reduced capital expenditures due to steps taken to align operations with the MYRP orders, resulting in more maintenance activities.

•Absence of major storm-related cost deferrals in 2024 increased expense by $4 million.

•Vegetation management costs increased by $4 million due to increased activity.

•Labor expense increased by $3 million due to assistance provided to other utilities to aid in storm recovery efforts, primarily caused by hurricane damage.

The following items partially offset the above increases in other operations and maintenance expenses between years:

•Reduction in environmental remediation rider costs of $14 million.

•Technology-related expenditures decreased $3 million resulting from lower levels of software licenses and rentals.

Other operations and maintenance costs decreased $7 million in 2024, compared with 2023, primarily due to a decrease of $6 million in contractor service costs and a $4 million decrease in labor expense due to steps taken to align operations with the November 2023 ICC natural gas rate order. These decreases were partially offset by an increase of $2 million in cloud computing costs.

Other operations and maintenance expenses increased $8 million in 2024, compared with 2023, primarily because of increased costs related to ATXI’s operations control center, which was placed in service in December 2023. ATXI provides affiliates with access to this facility. The rent expense associated with this facility is an affiliate transaction and eliminated in consolidation for purposes of Ameren’s consolidated financial statements. See Note 13 - Related-party Transactions under Part II, Item 8, of this report for additional information.

Depreciation and Amortization Expenses

(a)Includes other/intersegment eliminations of $8 million and $7 million in 2024 and 2023, respectively.

Depreciation and amortization expenses increased $203 million, $134 million, and $63 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively, primarily because of additional property, plant, and equipment investments across their respective segments. In addition, Ameren’s and Ameren Missouri’s depreciation and amortization expenses were affected by the following items, which include the effect of the additional investments at Ameren Missouri:

•The deferral to a regulatory liability related to production tax credits allowed under the IRA associated with the Callaway Energy Center that increased expenses by $90 million.

•Increased depreciation and amortization of $40 million due to the inclusion in base rates of amounts previously deferred under the PISA and RESRAM effective July 9, 2023, pursuant to the June 2023 MoPSC electric rate order.

•Increased amortization of prior deferrals and the lower net under-recovery of RESRAM eligible expenses increased depreciation and amortization expenses by $33 million.

•Depreciation and amortization rate changes pursuant to the electric rate order noted above, which increased depreciation and amortization expenses by $4 million.

•Depreciation and amortization expenses reflected a deferral to a regulatory asset of depreciation associated with investments in eligible property, plant, and equipment not yet included in base rates, pursuant to PISA and RESRAM. Base rates were updated to include the eligible property, plant, and equipment in-service through December 31, 2022, when new customer rates became effective on July 9, 2023, pursuant to the June 2023 MoPSC electric rate order. The effect of rebasing PISA and RESRAM, partially offset by increased amortization of prior PISA deferrals, decreased depreciation and amortization by $30 million.

•The higher net deferral pursuant to a tracker related to certain excess deferred income taxes, which decreased depreciation and amortization expenses by $5 million.

Taxes Other Than Income Taxes

(a)Includes $9 million and $8 million at Ameren Transmission in 2024 and 2023, respectively, and other/intersegment eliminations of $13 million and $12 million in 2024 and 2023, respectively.

Taxes other than income taxes increased $25 million in 2024, compared with 2023, primarily because of an increase of $7 million and $2 million at Ameren Missouri and Ameren Illinois Electric Distribution, respectively, due to the absence in 2024 of employee retention tax credits received under the Coronavirus Aid, Relief, and Economic Security Act; a $9 million increase at Ameren Illinois Natural Gas due to an increase in excise taxes, primarily resulting from higher invested capital taxes; and a $3 million increase in gross receipts taxes at Ameren Missouri, primarily due to increased retail electric sales.

Other Income, Net

See Note 6 – Other Income, Net under Part II, Item 8, of this report for additional information. See Note 5 – Long-term Debt and Equity Financings and Note 10 – Retirement Benefits under Part II, Item 8, for additional information on the debt extinguishment and the non-service cost components of net periodic benefit income.

Ameren

Other income, net, increased $69 million in 2024, compared with 2023. In addition to changes discussed below, other income, net, increased $14 million for activity not reported as part of a segment, primarily due to lower charitable contributions of $18 million at Ameren (parent) and a gain of $16 million for Ameren (parent)’s repurchase of senior secured notes and first mortgage bonds issued by Ameren Missouri and first mortgage bonds issued by Ameren Illinois. These increases were partially offset by a decrease of $13 million due to the non-service cost component of net periodic benefit income for activity not reported as part of a segment and $7 million in intersegment eliminations.

Other income, net, decreased $2 million in 2024, compared with 2023 due to a decrease of $5 million in lower allowance for equity funds used during construction, primarily related to lower average construction work in progress balances and a decrease of $2 million in the non-service cost component of net periodic benefit income. These decreases were partially offset by the increase of $4 million in other interest income on regulatory balances.

Other income, net, increased $66 million in 2024, compared with 2023, primarily because of an increase of $42 million in the non-service cost component of net periodic benefit income because of changes in the base level of pension and postretirement costs pursuant to the June 2023 MoPSC electric rate order. Other income, net, also increased $28 million because of a higher allowance for equity funds used during construction resulting from higher average construction work in progress balances. These increases were offset by a decrease of $2 million in other interest income on regulatory balances.

Other income, net, decreased $9 million in 2024, compared with 2023. Other income, net, decreased primarily because of a decrease of $12 million and $6 million in the non-service cost component of net periodic benefit income at Ameren Illinois Electric Distribution and Ameren Illinois Natural Gas, respectively. Other income, net decreased $2 million in the allowance of equity funds used during construction, largely at Ameren Illinois Electric Distribution. These decreases were partially offset by the increase in other interest income on regulatory balances of $11 million, largely at Ameren Illinois Electric Distribution.

Interest Charges

See Note 4 – Short-term Debt and Liquidity under Part II, Item 8, of this report and the Long-term Debt and Equity section below for additional information on short-term borrowings and long-term debt, respectively.

Ameren

Interest charges increased $97 million in 2024, compared with 2023. In addition to changes by segments discussed below, interest charges increased $42 million for activity not reported as part of a segment, primarily at Ameren (parent), because of issuances of long-term debt in November and December of 2023, which collectively increased interest charges by $64 million. The net proceeds from these issuances were used to repay short-term borrowings, which decreased short-term interest expense by $23 million, compared with 2023.

Interest charges increased $21 million in 2024, compared with 2023, primarily due to issuances of long-term debt in May 2023, June 2024 and August 2024, which collectively increased interest charges by $9 million. Additionally, an increase on long-term debt and a higher interest rate on an increased level of short-term borrowings increased interest charges by $8 million and $2 million, respectively.

Interest charges increased $17 million in 2024, compared with 2023, primarily due to issuances of long-term debt in March 2023, January 2024, April 2024, and October 2024, which collectively increased interest charges by $48 million.

The following items partially offset the above increase in interest charges between years:

•Increase in the borrowed funds capitalized as part of the allowance for funds used during construction of $12 million, primarily due to higher average construction work in progress balances.

•Interest charges decreased by $9 million due to the maturity of $350 million senior secured notes bearing a 3.5% interest rate in April 2024 that were repaid with cash on hand.

•Interest charges reflected a deferral to a regulatory asset of interest associated with investments in eligible property, plant, and equipment not yet included in base rates, pursuant to PISA and RESRAM. Base rates were updated to include the eligible property, plant, and equipment in-service through December 31, 2022, when new customer rates became effective on July 9, 2023, pursuant to the June 2023 MoPSC electric rate order. This update to base rates resulted in a higher deferral of interest in 2024 pursuant to PISA and RESRAM that decreased interest charges by $5 million.

•Lower levels of short-term borrowings decreased interest charges by $4 million.

Interest charges increased $37 million in 2024, compared with 2023, primarily due to the following:

Interest charges increased by $20 million, primarily due to issuances of long-term debt in May 2023 and June 2024, which increased interest charges by $10 million. Additionally, an increase of interest on long-term debt, a higher interest rate on an increased level of short-term borrowings, and interest charges resulting from the October 2024 FERC ROE order increased interest charges by $4 million, $2 million, and $2 million, respectively.

Interest charges increased by $9 million, primarily due to issuances of long-term debt in May 2023 and June 2024, which increased interest charges by $11 million.

Interest charges increased by $8 million, primarily due to issuances of long-term debt in May 2023 and June 2024.

Income Taxes

The following table presents effective income tax rates for the years ended December 31, 2024 and 2023:

See Note 12 – Income Taxes under Part II, Item 8, of this report for information regarding reconciliations of effective income tax rates for Ameren, Ameren Missouri, and Ameren Illinois.

The effective tax rate was lower at Ameren Illinois Electric Distribution in 2024, compared with 2023, primarily due to an increase in excess deferred tax amortization pursuant to an ICC order, which was offset by a corresponding decrease in revenues.