Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 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 Identification ...

Financial Data and Key Metrics Changes - Alliant Energy reported ongoing earnings per share (EPS) growth of $0.18 for 2025 compared to 2024, driven by increased revenue requirements from rate-based increases and favorable temperature impacts on electric and gas sales [13][14] - The company achieved a 10-year compound annual EPS growth of 6.3%, with ongoing EPS growth of 6% in 2025, exceeding the midpoint of guidance [5][14] - A total shareholder return of over 13% was delivered for the year, marking the 22nd consecutive year of dividend increases [5] Business Line Data and Key Metrics Changes - In Wisconsin, Alliant Energy completed 275 MW of energy storage investments and turbine upgrades, contributing to regulatory execution strength [6] - Electric sales increased by nearly 1% in 2025 compared to 2024, primarily driven by higher commercial and industrial sales [14] - The company closed the year with four executed electric service agreements (ESAs) totaling 3 GW of peak load, indicating a 50% future growth in demand [9] Market Data and Key Metrics Changes - The company is actively engaged with customers and pursuing 2-4 gigawatts of additional large load growth opportunities beyond current projections [10] - The approval of individual customer rate contracts in Iowa supports economic development while maintaining flat retail electric base rates for existing customers [8] Company Strategy and Development Direction - Alliant Energy's strategy focuses on unlocking customer and community potential, with significant capital investments in data centers that strengthen local tax bases [6][7] - The company aims to be a partner of choice, aligning capital and regulatory solutions to enable growth while meeting customer and shareholder expectations [9] - A proactive approach to safe harboring renewable and energy storage investments is emphasized to maintain reliability and cost-effectiveness [11] Management's Comments on Operating Environment and Future Outlook - Management highlighted the importance of navigating public policy shifts and the acceleration of electric demand as key factors influencing performance [5] - The company expects a compound annual earnings growth rate of 7%+ from 2027 to 2029, based on current projections for capital expenditure plans and data center load [18] - Management expressed confidence in executing projects within the updated capital expenditure plan, with a focus on maintaining stable base rates for customers [19][21] Other Important Information - The company has a four-year capital plan of approximately $13.4 billion, with a balanced mix of funding sources including cash from operations and new financings [20] - Regulatory decisions in Iowa and Wisconsin are aligned with capital investment plans, reducing regulatory uncertainty for 2026 [21][23] Q&A Session Summary Question: On the 3 GW of data centers, what are the minimum take agreements? - Management confirmed that any additional demand from hyperscalers would be accretive to current planning assumptions [30] Question: How are conversations with hyperscalers evolving, especially regarding stricter safeguards? - Management noted that Iowa has strategic advantages for data center growth, and they are committed to ensuring Wisconsin remains open for business [32] Question: What is the path to construction for the relocated QTS project? - Management clarified that they are using individual customer rate constructs for both states and are pleased with their ability to pivot quickly [42] Question: What are the goals for timing on bringing in another deal for the 2-4 GW of growth? - Management indicated that they have three buckets of opportunities and are focused on high-quality electric service agreements [44] Question: Is the 1% retail sales growth assumption conservative? - Management stated that most data center load is expected to come in 2027 and beyond, making the 1% growth assumption consistent with current expectations [53] Question: How does the shift in renewables in CapEx relate to QTS? - Management explained that the shift is part of a consistent investment plan and reflects a proactive approach to meet customer needs [57]

Financial Data and Key Metrics Changes - Alliant Energy reported ongoing earnings per share (EPS) growth of $0.18 for 2025 compared to 2024, driven by increased revenue requirements from rate-based increases and favorable temperature impacts on electric and gas sales [13][14] - The company achieved a 10-year compound annual EPS growth of 6.3%, with ongoing EPS growth of 6% in 2025, exceeding the midpoint of guidance [5][14] - A total shareholder return of over 13% was delivered for the year, marking the 22nd consecutive year of dividend increases [5] Business Line Data and Key Metrics Changes - In Wisconsin, Alliant Energy completed 275 MW of energy storage investments and turbine upgrades, contributing to regulatory execution strength [6] - Electric sales increased by nearly 1% in 2025 compared to 2024, primarily driven by higher commercial and industrial sales [14] - The company has a backlog of opportunities to drive future growth, including four executed electric service agreements (EFAs) totaling 3 GW of peak load [9] Market Data and Key Metrics Changes - The company is focused on capturing growth opportunities in both Iowa and Wisconsin, with a commitment to keep Iowa retail electric base rates flat for existing customers through the end of the decade [8] - Alliant Energy is actively engaged with customers to pursue 2-4 GW of additional large load growth opportunities beyond current projections [10] Company Strategy and Development Direction - The company aims to unlock the potential of customers and communities, with a focus on data centers as significant capital investments that benefit local tax bases [6][7] - Alliant Energy's strategy includes maximizing existing resources, extending asset life, and integrating renewables and energy storage facilities to maintain reliability [11] - The company emphasizes a proactive approach to economic development, ensuring that customers benefit from data center growth without incurring additional costs [76] Management's Comments on Operating Environment and Future Outlook - Management highlighted the importance of agility and disciplined decision-making in navigating the evolving energy landscape [10] - The company expects a compound annual earnings growth rate of 7%+ from 2027 to 2029, based on current projections for capital expenditure plans and data center load [18] - Management expressed confidence in the ability to execute projects within the updated capital expenditure plan, supported by a strong liquidity position [19] Other Important Information - Alliant Energy's four-year capital plan remains on track, with a total expected common equity need of approximately $2.4 billion, of which $1 billion has already been raised [20] - The company achieved several constructive regulatory decisions throughout the year, aligning its regulatory agenda with capital investment plans [21] Q&A Session Summary Question: What are the minimum take agreements for the 3 GW of data centers? - Management confirmed that any additional demand from hyperscalers would be accretive to current planning assumptions [30] Question: How are conversations with hyperscalers evolving, especially regarding Wisconsin and Iowa? - Management noted that Iowa has strategic advantages, and they are committed to ensuring Wisconsin remains open for business, despite local challenges [32] Question: What is the path to construction for the relocated QTS data center? - Management indicated that they are pleased with their ability to pivot quickly and are working on the necessary permitting and zoning approvals [42] Question: What are the expectations for retail sales growth in 2026? - Management expects retail sales growth of approximately 1%, with most data center load anticipated to come in 2027 and beyond [53] Question: How does the shift in renewables and gas generation relate to the QTS project? - Management clarified that the shift is part of a consistent investment plan, with adjustments made to accommodate the relocated load [57]

Financial Data and Key Metrics Changes - In 2025, Alliant Energy achieved ongoing earnings per share (EPS) growth of $0.18 compared to 2024, driven by increased revenue from rate-based increases and favorable temperature impacts on electric and gas sales [11][12] - The company reported a 10-year compound annual EPS growth of 6.3%, with ongoing EPS growth of 6% in 2025, exceeding the midpoint of guidance [4][11] - A total shareholder return of over 13% was delivered for the year, and the dividend was increased for the 22nd consecutive year [4] Business Line Data and Key Metrics Changes - Electric sales increased by nearly 1% in 2025 compared to 2024, primarily due to higher commercial and industrial sales across both IPL and WPL [12] - The company completed 275 MW of energy storage investments and turbine upgrades in Wisconsin, contributing to operational performance [5] Market Data and Key Metrics Changes - In Iowa, the approval of individual customer rate contracts supports economic development while maintaining flat retail electric base rates for existing customers through the end of the decade [6] - The company closed the year with four executed Electric Service Agreements (EFAs) totaling 3 GW of peak load, indicating a 50% future growth in demand [7] Company Strategy and Development Direction - Alliant Energy's strategy focuses on unlocking customer and community potential, with significant capital investments in data centers that enhance local tax bases and support public services [5] - The company aims to attract large load customers by ensuring regulatory solutions align with customer needs, emphasizing a customer-centric approach [6][7] - A proactive approach to renewable and energy storage investments is central to the company's strategy, with plans to maximize existing resources and extend asset life [9] Management's Comments on Operating Environment and Future Outlook - Management highlighted the importance of agility and disciplined decision-making in navigating the evolving energy landscape, with a focus on long-term value [7][9] - The company expects to pursue industry-leading demand growth and successful project execution, with a compound annual earnings growth rate of 7%+ projected for 2027-2029 [16] Other Important Information - The company has a four-year capital expenditure plan of approximately $13.4 billion, with funding through a mix of cash from operations and new financings [18] - Regulatory decisions in Iowa and Wisconsin are aligned with capital investment plans, reducing regulatory uncertainty for 2026 [19][20] Q&A Session Summary Question: Minimum take agreements for the 3 GW of data centers - Management confirmed that any additional demand from hyperscalers would be accretive to current planning assumptions [26] Question: Conversations with hyperscalers and data center developments - Management noted that Iowa has strategic advantages over Wisconsin for data center growth, and they are committed to ensuring Wisconsin remains open for business [29] Question: Path to construction for the relocated QTS project - Management clarified that they are pleased with their ability to pivot quickly and have a robust plan for the new site [39] Question: Timing for additional deals in the 2-4 GW range - Management indicated that they are in active discussions and have structured their approach to ensure high-quality Electric Service Agreements [41] Question: Land control and zoning for new projects - Management confirmed that they own considerable land zoned for industrial use, which supports their economic development strategy [48] Question: Retail sales growth assumptions for 2026 - Management expects retail sales growth of approximately 1%, consistent with 2025, with significant data center load anticipated in 2027 and beyond [50] Question: Shift in capital expenditures related to QTS - Management explained that the shift in capital expenditures is primarily a refinement of their planning process rather than a significant change [64] Question: Regulatory continuity amid gubernatorial races - Management emphasized their commitment to reliability and affordability, ensuring that customers benefit from data center growth [72] Question: Local concerns regarding data center developments in Wisconsin - Management indicated that challenges are primarily at the township level, with local support for data centers being crucial [75]

Alliant Energy Corporation Q4 2025 Earnings Call February 20, 2026 2025 Q4 Earnings Call 2 ALLIANT ENERGY 2025 Highlights 6.3% 10-year earnings CAGR | Financial Results | 2025 | 2024 | | --- | --- | --- | | GAAP net income (in millions) | $810 | $690 | | GAAP earnings per share (EPS) | $3.14 | $2.69 | | Ongoing EPS | $3.22 | $3.04 | Cautionary Statements Forward-looking Statements The information regarding earnings per share guidance, dividend target, earnings per share growth, load growth, capital expendit ...

Core Insights - Alliant Energy Corporation (LNT) reported fourth-quarter 2025 operating earnings of 60 cents per share, exceeding the Zacks Consensus Estimate of 58 cents by 3.45%, but down 14.29% from 70 cents in the same quarter last year [1] - The company achieved total revenues of $1.06 billion, surpassing the Zacks Consensus Estimate of $0.94 billion by 13.45%, and reflecting a year-over-year increase of 9.01% from $0.98 billion [2] - Adjusted earnings for 2025 were reported at $3.22 per share, a 5.92% increase from $3.04 in 2024 [1] Financial Performance - Total operating expenses rose to $868 million, a 15.12% increase from $754 million in the previous year, primarily due to higher costs in electric production fuel and purchased power [3] - Operating income decreased to $196 million, down 11.71% from $222 million in the year-ago period [3] - Interest expenses increased by 16.7% to $140 million compared to the prior year [4] Sales and Production - Total utility electric sales were reported at 7,907 thousand megawatt-hours, a decrease of 2.58% from the previous year [4] - Total utility gas sold and transported increased to 46,558 thousand dekatherms, reflecting a year-over-year growth of 4.63% [4] Cash Flow and Debt - As of December 31, 2025, cash and cash equivalents stood at $556 million, a significant increase from $81 million as of December 31, 2024 [5] - Long-term debt rose to $10.95 billion from $8.68 billion in the previous year [5] - Cash flow from operating activities was reported at $1.169 billion, slightly up from $1.167 billion in the prior year [5] Future Guidance - For 2026, Alliant Energy expects earnings per share to be in the range of $3.36 to $3.46, with long-term EPS growth projected at 5-7% for 2027-2029 [8] - The company anticipates a 1% growth in retail sales, driven by data center construction and commissioning sales [9] - Planned capital expenditures for 2026 are estimated at $3 billion, with a total of $13.4 billion earmarked for the period from 2026 to 2029 [9]

Alliant Energy said 2025 GAAP EPS rose to $3.14 from $2.69 in 2024, while ongoing (non-GAAP) EPS increased to $3.22 from $3.04, representing 6% growth. The company affirmed 2026 ongoing EPS guidance of $3.36–$3.46. Management framed the year’s performance around execution on a growing regulated investment plan and “growing customer demand,” including an updated arrangement tied to QTS, a major data center operator, after renegotiating an electric service agreement based on a new project location. Allia ...

Core Insights - Alliant Energy reported quarterly earnings of $0.6 per share, exceeding the Zacks Consensus Estimate of $0.58 per share, but down from $0.7 per share a year ago, resulting in an earnings surprise of +3.45% [1] - The company achieved revenues of $1.06 billion for the quarter ended December 2025, surpassing the Zacks Consensus Estimate by 13.45% and up from $976 million year-over-year [2] - Alliant Energy shares have increased approximately 7% year-to-date, outperforming the S&P 500's gain of 0.5% [3] Earnings Outlook - The current consensus EPS estimate for the upcoming quarter is $0.85 on revenues of $1.15 billion, and for the current fiscal year, it is $3.43 on revenues of $4.37 billion [7] - The estimate revisions trend for Alliant Energy was mixed prior to the earnings release, resulting in a Zacks Rank 3 (Hold) for the stock, indicating expected performance in line with the market [6] Industry Context - The Utility - Electric Power industry is currently ranked in the top 36% of over 250 Zacks industries, suggesting that companies in the top 50% outperform those in the bottom 50% by more than 2 to 1 [8] - Another company in the same industry, Algonquin Power & Utilities, is expected to report a quarterly earnings decline of -33.3% with revenues projected at $568.72 million, down 2.8% from the previous year [9][10]

Alliant Energy beats quarterly profit estimates on strong power demand | ReutersSkip to main content[Exclusive news, data and analytics for financial market professionalsLearn more aboutRefinitiv]- Companies[Alliant Energy Corp]FollowFeb 19 (Reuters) - U.S. utility Alliant Energy [(LNT.O), opens new tab] beat Wall Street estimates for fourth-quarter profit on Thursday, benefiting from robust power demand and strong performance in its electric and gas segments.U.S. electricity use reached record highs last y ...

Exhibit 99.1 Alliant Energy Corporation Corporate Headquarters 4902 North Biltmore Lane Madison, WI 53718-2148 www.alliantenergy.com News Release FOR IMMEDIATE RELEASE "In 2025, we delivered another solid year of financial and operational results. We're executing well while investing to meet growing customer demand," said Lisa Barton, Alliant Energy President and CEO. "We have renegotiated an electric service agreement with QTS based on a new project location and our investment plan reinforces our flexibili ...