Core Viewpoint - Alliant Energy (LNT) is set to release its second-quarter 2025 results on August 7, following a significant negative earnings surprise of 45.6% in the previous quarter [1] Group 1: Factors Impacting Q2 Performance - The Janesville Community Solar Garden, a 2.25-megawatt project, began generating energy in May 2025, likely contributing positively to the upcoming quarterly results [2] - Alliant Energy's 200-MW solar facility in Linn County, renamed Pleasant Creek Solar, became operational during Q2 2025, expected to power approximately 40,000 homes annually, which may enhance the company's bottom-line performance [3] - An order from the IUC authorized annual base rate increases of $185 million for IPL's retail electric customers and $10 million for retail gas customers, likely boosting revenues for the quarter [4] - Increased demand from data centers and capital investments are expected to further support the bottom-line performance [4] - However, higher depreciation expenses and financing costs may have negatively impacted quarterly performance [5] Group 2: Q2 Expectations - The Zacks Consensus Estimate for earnings is 62 cents per share, reflecting a year-over-year increase of 8.8% [6] - Revenue estimates are set at $987.4 million, indicating a year-over-year increase of 10.5% [6] - Total electricity delivered is estimated at 7,729.98 megawatt-hours (MWh), up 0.4% year over year [6] Group 3: Earnings Prediction - The current model does not predict an earnings beat for Alliant Energy, with an Earnings ESP of +0.27% and a Zacks Rank of 4 (Sell) [7][8] - The combination of a positive Earnings ESP and a higher Zacks Rank typically increases the odds of an earnings beat, which is not the case for Alliant Energy this time [7] Group 4: Additional Context - New solar facilities launched in Wisconsin and Iowa are expected to enhance Q2 energy generation [9] - Rate increases for IPL electric and gas customers may have supported second-quarter revenues [9] - Earnings are likely under pressure from increased depreciation and financing expenses [9]

Core Viewpoint - Alliant Energy Corporation (LNT) is benefiting from investments in renewable energy and infrastructure upgrades, which support its expanding customer base and profitability [1][2][8] Group 1: Positive Factors - Alliant Energy's earnings prospects are bolstered by increasing electric and natural gas customer volumes, favorable geographic location, and regulatory developments that support wind project development [2] - The ongoing economic development in its service areas is driving demand for utility services, enhancing performance [2] - The company plans to invest $11.5 billion from 2025 to 2028 to strengthen its electric and gas distribution network and expand its renewable energy assets, raising its long-term capital expenditure guidance by 26% [3][8] Group 2: Investment Plans - Alliant Energy's investment strategy is expected to support an 11% compound annual growth rate (CAGR) in rate base from 2025 to 2028, with over 40% of capital expenditures focused on wind, solar, and energy storage [4][8] - These investments position Alliant Energy as having one of the cleanest generation asset portfolios in the country [4] Group 3: Challenges - The company's utility operations rely on third-party electric transmission systems, which could limit its ability to transmit electricity if those systems underperform [5] - Increased competition from self-generation by large industrial customers and alternative energy sources may reduce demand for Alliant Energy's services in Iowa and Wisconsin [6] Group 4: Stock Performance - Over the past month, Alliant Energy's shares have increased by 1.8%, outperforming the industry's growth of 1.3% [7]

Core Insights - Alliant Energy Corporation (LNT) reported first-quarter 2025 operating earnings of 83 cents per share, exceeding the Zacks Consensus Estimate of 57 cents by 45.6% and increasing 33.9% from the previous year's 62 cents [1] - Revenues for LNT totaled $1.128 billion, slightly surpassing the Zacks Consensus Estimate of $1.126 billion by 0.17% and reflecting a 9.4% increase from $1.031 billion in the same quarter last year [1] Financial Performance - Total operating expenses were $871 million, up 7.7% from $809 million in the year-ago period, driven by higher electric production fuel and purchased power costs [2] - Operating income reached $257 million, marking a 15.8% increase from the previous year's figure [2] - Interest expenses rose to $119 million, an increase of 11.2% from the prior-year period [2] Customer and Sales Metrics - The number of retail electric customers increased by 0.7% and retail gas customers by 0.6% year over year [3] - Total utility electric sales were 8,257 thousand megawatt-hours, down 1.1% from the year-ago quarter [3] - Total utility gas sold and transported was 54,828 thousand dekatherms, up 1.5% year over year [3] Financial Position - As of March 31, 2025, cash and cash equivalents were $25 million, down from $81 million as of December 31, 2024 [4] - Long-term debt totaled $8.58 billion, a decrease from $8.68 billion as of December 31, 2024 [4] - Cash flow from operating activities in the first quarter of 2025 was $249 million, compared to $307 million in the first quarter of 2024 [4] Future Outlook - Alliant Energy anticipates 2025 earnings in the range of $3.15-$3.25 per share, with the Zacks Consensus Estimate at $3.22 per share [5] - The company plans to invest $11.5 billion from 2025 to 2028 to enhance its infrastructure [5] Zacks Rank - Alliant Energy currently holds a Zacks Rank 3 (Hold) [6]

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2025 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Name of Registrant, State of Incorporation, Address of Principal Executive Offices, Telephone Number, Commission File Number, IRS Employer Identific ...

Financial Data and Key Metrics Changes - The company reported first quarter earnings of $0.83 per share, an increase from $0.62 per share in the same quarter of the previous year, reflecting strong performance despite adverse temperature impacts on sales [19][20] - The earnings for the first quarter represented more than 25% of the company's earnings guidance midpoint for 2025, reaffirming the guidance range of $3.15 to $3.25 per share [6][21] - The capital expenditure plan for 2025 through 2028 has been updated to reflect a nearly 26% increase from 18 months ago, translating into a forecasted investment CAGR of nearly 11% [11][24] Business Line Data and Key Metrics Changes - The company has secured energy supply agreements (ESAs) totaling 2.1 gigawatts of demand from three major data center developments, representing a greater than 30% increase in peak demand [10][12] - Retail electric sales margins improved compared to the first quarter of the previous year, driven by customer growth and increased usage per meter across all customer classes [20] Market Data and Key Metrics Changes - The company is actively participating in the MISO capacity auction, selling excess capacity to benefit customer bills, positioning itself favorably compared to competitors [80] - The company is experiencing strong interest in economic development opportunities in its service areas, particularly in Iowa and Wisconsin [11][15] Company Strategy and Development Direction - The company is focused on supporting economic development and growth in its states, with a commitment to customer needs and sustainable investor returns [6][8] - The capital plan includes investments in new natural gas resources to complement renewable energy sources, ensuring a balanced energy resource mix [12][17] - The company is taking a proactive approach to manage risks related to potential changes in tax legislation, emphasizing the importance of tax credits for economic growth [16][25] Management's Comments on Operating Environment and Future Outlook - Management expressed confidence in achieving 2025 earnings objectives while advancing key strategic priorities, despite challenges in the macroeconomic environment [6][11] - The company is committed to maintaining a strong balance sheet and investment-grade credit ratings while navigating potential legislative changes [24][25] Other Important Information - The updated financing plan anticipates raising approximately $1.4 billion in new common equity through 2028, with flexibility in timing based on market conditions [74][76] - The company has completed nearly all planned safe harbor activities to preserve tax credits for future projects, significantly mitigating tariff exposure [22][25] Q&A Session Summary Question: Timeline for converting mature opportunities to contracts - Management indicated a high level of confidence in converting mature opportunities into contracts, with ongoing discussions and negotiations [35][36] Question: Impact of tax policy changes on rate case provisions - Management clarified that while there is a provision to revisit rate cases if significant legislative changes occur, the focus is on avoiding the need to do so through proactive growth strategies [40][42] Question: Long-term EPS CAGR outlook - Management reaffirmed a long-term EPS CAGR of 5% to 7%, with current plans indicating potential for growth towards the upper end of that range starting in 2027 [48][50] Question: Details on the CapEx increase - The increase in the capital expenditure plan was primarily driven by investments in natural gas generation to meet growing demand from data centers [76][77] Question: MISO capacity auction impact on consumer bills - Management noted that the company is well-positioned to leverage auction results to benefit customer bills, contrasting with competitors who may face challenges [80] Question: Regulatory filings for additional generation resources - Management provided insights into upcoming regulatory filings for new generation resources, emphasizing flexibility in their resource planning [67][69]

Financial Data and Key Metrics Changes - The company reported first quarter earnings of $0.83 per share, an increase from $0.62 per share in the same quarter of the previous year, reflecting a strong start to 2025 [19] - Earnings for the first quarter accounted for more than 25% of the company's earnings guidance midpoint for 2025 [6] - The company reaffirmed its 2025 earnings guidance range of $3.15 to $3.25 per share [21] Business Line Data and Key Metrics Changes - The company has seen a 30% increase in peak demand due to three major data center developments with fully executed energy supply agreements totaling 2.1 gigawatts [10] - The capital expenditure (CapEx) plan for 2025 through 2028 has increased by approximately $600 million, reflecting a nearly 26% increase from 18 months ago [11] - The updated CapEx plan translates into a forecasted investment compound annual growth rate (CAGR) of nearly 11% from 2024 to 2028 [11] Market Data and Key Metrics Changes - The company is actively pursuing growth opportunities in Iowa and Wisconsin, with strong interest from data center customers [11][15] - The company has successfully sold existing capacity into the recent MISO capacity auction, benefiting customer bills [22][80] Company Strategy and Development Direction - The company is focused on supporting economic development and growth in its service areas, emphasizing collaboration with stakeholders [6][15] - The strategy includes a balanced approach to energy resources, incorporating wind, batteries, and natural gas to ensure reliability and sustainability [17] - The company is committed to maintaining a strong balance sheet while exploring various financing options, including equity and debt [24][25] Management's Comments on Operating Environment and Future Outlook - Management expressed confidence in achieving 2025 earnings objectives while navigating a complex macroeconomic environment [6][11] - The company is proactively managing risks related to potential changes in tax credits and tariffs, ensuring that a significant portion of tax credits is safe harbored through 2028 [16][22] - Management highlighted the importance of regulatory support and community partnerships in driving long-term growth [15][27] Other Important Information - The company has updated its financing plans for 2025 through 2028, with anticipated financing sources including cash from operations and new debt financing [24] - The company is actively engaged in regulatory initiatives, including rate reviews and requests for new generation resources in both Iowa and Wisconsin [27][30] Q&A Session Summary Question: Timeline for converting mature opportunities to contracts - Management indicated a high level of confidence in converting mature opportunities into contracts, with ongoing discussions and negotiations [35][36] Question: Impact of safe harboring on rate case provisions - Management clarified that while there is a provision to revisit rate cases if legislation changes significantly, the focus is on avoiding the need to do so through proactive growth strategies [40][41] Question: Long-term EPS CAGR outlook - Management reaffirmed a long-term EPS CAGR of 5% to 7%, with current plans indicating potential for growth towards the top end of that range by 2027 [48][50] Question: Details on CapEx increase - The increase in CapEx was primarily associated with natural gas generation to meet the growing demand from data centers [76][77] Question: Impact of MISO capacity auction on consumer bills - Management stated that the company is well positioned to benefit from elevated capacity prices, which will help mitigate customer bills [80] Question: Regulatory filings for additional generation resources - Management confirmed ongoing regulatory filings for new generation resources, with specific megawatt details to be provided in supplemental slides [67][68]

Financial Data and Key Metrics Changes - The company reported first quarter earnings of $0.83 per share, an increase from $0.62 per share in the same quarter of the previous year, reflecting a strong start to 2025 [17] - Earnings for the quarter accounted for more than 25% of the company's earnings guidance midpoint for 2025, reaffirming the guidance range of $3.15 to $3.25 per share [5][19] - The increase in earnings was driven by higher revenue requirements from capital investments, despite negative temperature impacts on electric and gas sales [17][18] Business Line Data and Key Metrics Changes - The company has secured energy supply agreements (ESAs) totaling 2.1 gigawatts of demand from three major data center developments, representing a greater than 30% increase in peak demand [8][9] - The capital expenditure (CapEx) plan has been updated to reflect a nearly 26% increase from 18 months ago, translating to a forecasted investment compound annual growth rate (CAGR) of nearly 11% from 2024 to 2028 [9][10] Market Data and Key Metrics Changes - The company is experiencing strong interest in economic development within its service areas in Iowa and Wisconsin, with ongoing efforts to support growth through new energy supply agreements [9][12] - The company has successfully sold existing capacity into the recent MISO capacity auction, which is expected to benefit customer bills [20][76] Company Strategy and Development Direction - The company is focused on an "all of the above" approach to new generation resources, including a mix of wind, batteries, and natural gas, to maintain a balanced energy resource mix [15] - The updated capital plan includes significant investments in natural gas generation to meet the growing demand from data centers, with a focus on enhancing reliability and affordability [10][72] Management's Comments on Operating Environment and Future Outlook - Management expressed confidence in achieving 2025 earnings objectives while advancing key strategic priorities, emphasizing the importance of supporting economic development [5][6] - The company is proactively managing risks related to potential changes in tax credits and tariffs, with a focus on maintaining a strong balance sheet and investment-grade credit ratings [24][52] Other Important Information - The company has completed nearly all planned safe harbor activities to preserve tax credits for future energy storage and renewable projects expected to be placed into service through 2028 [20] - The company is committed to ensuring that all individual customer rates achieve a win-win for existing customers, new customers, and shareholders [11] Q&A Session Summary Question: Timeline for converting mature opportunities to contracts and breakdown of serving those opportunities - Management indicated that they have high confidence in converting mature opportunities into contracts and are using existing resources to accelerate load growth [34][35] Question: Impact of safe harboring on the ability to go back for a rate case in Iowa - Management clarified that they are focused on activities to avoid the need to go back for a rate case and are advocating for beneficial legislative provisions [38][39] Question: Long-term EPS CAGR outlook - Management reaffirmed a long-term EPS CAGR of 5% to 7%, with current plans indicating potential for growth towards the top end of that range starting in 2027 [45][46] Question: Details on the CapEx increase - The increase in CapEx was primarily associated with natural gas generation to meet the peak demand from data center opportunities [72] Question: Impact of MISO capacity auction on consumer bills - Management stated that they are well positioned to utilize proceeds from the auction to help customer bills, contrasting with other entities that may face challenges [76] Question: Regulatory initiatives and filings in Iowa and Wisconsin - Management discussed ongoing regulatory filings for new generation resources and the potential for maintaining flat base rates through growth and cost reduction [60][61]

Core Insights - Alliant Energy reported quarterly earnings of $0.83 per share, exceeding the Zacks Consensus Estimate of $0.57 per share, and showing an increase from $0.62 per share a year ago, resulting in an earnings surprise of 45.61% [1] - The company generated revenues of $1.13 billion for the quarter ended March 2025, surpassing the Zacks Consensus Estimate by 0.17% and up from $1.03 billion year-over-year [2] - Alliant Energy's stock has increased approximately 4.5% since the beginning of the year, contrasting with a -4.3% decline in the S&P 500 [3] Earnings Outlook - The current consensus EPS estimate for the upcoming quarter is $0.58 on revenues of $1.02 billion, and for the current fiscal year, it is $3.22 on revenues of $4.29 billion [7] - The estimate revisions trend for Alliant Energy is mixed, leading to a Zacks Rank 3 (Hold), indicating expected performance in line with the market [6] Industry Context - The Utility - Electric Power industry is currently ranked in the top 22% of over 250 Zacks industries, suggesting a favorable outlook compared to lower-ranked industries [8] - Empirical research indicates a strong correlation between near-term stock movements and trends in earnings estimate revisions, which can be tracked by investors [5]

Q1 2025 Earnings Call Alliant Energy Corporation Cautionary Statements Forward-looking Statements The information regarding forecasted earnings per share, forecasted effective income tax rates, capital expenditure plans, financing plans and sources of funding, and regulatory plans contain forward-looking statements. Actual results could differ materially because the realization of those results is subject to many uncertainties, including: the state of the economy in the service territories of IPL and WPL; s ...

Exhibit 99.1 Alliant Energy Corporation Corporate Headquarters 4902 North Biltmore Lane Madison, WI 53718-2148 www.alliantenergy.com News Release FOR IMMEDIATE RELEASE Media Hotline: (608) 458-4040 Investor Relations: Susan Gille (608) 458-3956 ALLIANT ENERGY ANNOUNCES FIRST QUARTER 2025 RESULTS MADISON, Wis. - May 8, 2025 - Alliant Energy Corporation (NASDAQ: LNT) today announced U.S. generally accepted accounting principles (GAAP) consolidated unaudited earnings per share (EPS) for the three months ended ...