ALLIANT ENERGY CORP

NOTE 6. COMMON EQUITY

Common Share Activity -A summary of Alliant Energy’s common stock activity was as follows:

At-the-Market Offering Program - In May 2025, Alliant Energy filed a prospectus supplement and executed a related distribution agreement, under which it may sell up to $1.3 billion in aggregate of its common stock through 2028 through an at-the-market offering program that includes an equity forward sales component. Alliant Energy expects to use proceeds from the issuance of common stock for general corporate purposes.

Alliant Energy entered into forward sale agreements under its at-the-market offering program with various counterparties who, for the three and nine months ended September 30, 2025, borrowed and sold an aggregate of 7,851,080 and 10,764,103 shares of Alliant Energy common stock at an aggregate gross sales price of $508 million and $686 million, including approximately $4 million and $5 million in commissions, respectively, to the counterparties payable by Alliant Energy when the forward sale agreements are settled. Alliant Energy has not yet received any proceeds from this program and no amounts have been or will be recorded in equity on Alliant Energy’s balance sheets until the forward sale agreements settle. Alliant Energy currently expects to settle the forward sale agreements in 2026 through physical delivery of shares of common stock in exchange for cash proceeds at the then-applicable forward sale price; however, Alliant Energy may elect cash settlement or net share settlement for all or a portion of the obligations under the forward sale agreements. As of September 30, 2025, the weighted-average forward price, net of commissions, was $63.46 per share and is subject to daily adjustment based on a floating interest rate factor and decreased by other fixed amounts specified in the forward sale agreements. As of September 30, 2025, Alliant Energy could have settled all of its outstanding forward sale agreements under the at-the-market offering program with physical delivery of 10,764,103 shares of Alliant Energy common stock to the counterparties in exchange for cash of $683 million.

Alliant Energy has concluded that the forward sale agreements meet the derivative scope exception for certain contracts involving an entity’s own equity. Until settlement of the forward sale agreements, Alliant Energy’s EPS dilution resulting from the agreements, if any, is determined using the treasury stock method. Share dilution occurs when the average market price of Alliant Energy stock during the reporting period is higher than the forward sale price as of the end of the reporting period. As of September 30, 2025,199,923 incremental shares were included in the calculation of diluted EPS related to the securities under the forward sale agreements.

Changes in Shareowners’ Equity -A summary of changes in shareowners’ equity was as follows (in millions):