10-Q – 2026-07-31 – lnt-20260630.htm

(a) Refer to the cash flows statements for details of renewable tax credits transferred to other corporate taxpayers during the six months ended June 30, 2026 and 2025.

Investing Activities - The following items contributed to increased (decreased) inv esting activity cash flows for the six months ended June 30, 2026 compared to the same period in 2025 (in millions):

Alliant Energy IPL WPL

Changes in the amount of cash receipts on sold receivables $66 $66 $—
Lower (higher) utility construction and acquisition expenditures (a) 63 137 (74)
Higher non-utility construction and acquisition expenditures (20) — —
Other (10) (4) (15)
$99 $199 ($89)

(a) Largely due to lower expenditures for IPL’s energy storage and refurbishment of existing wind farms, partially offset by higher expenditures for WPL’s refurbishment of existing wind farms.

Financing Activities - The following items contributed to increased (decreased) fin ancing activity cash flows for the six months ended June 30, 2026 compared to the same period in 2025 (in millions):

Alliant Energy IPL WPL
Lower net proceeds from issuance of long-term debt ($1,162) ($594) $—
Higher payments to retire long-term debt (1,075) — —
Changes in common stock dividends (13) 100 10
Higher capital contributions from IPL’s and WPL’s parent company, Alliant Energy — 5 100
Net changes in the amount of commercial paper outstanding 936 89 (26)
Higher proceeds from issuance of other short-term borrowings 400 — —
Higher net proceeds from common stock issuances 58 — —

Other (11) (1) 3
($867) ($401) $87

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Common Stock Issuances - Refer to Note 5 for discussion of common stock issuances by Alliant Energy in 2026 and Alliant Energy’s at-the-market offering programs.

Short-term Debt - Refer to Note 6(a) for discussion of Alliant Energy’s term loan credit agreement entered into in 2026.

Long-term Debt - Refer to Note 6(b) for discussion of issuances and/or retirements of long-term debt by Alliant Energy, AEF and IPL in 2026.

Impact of Credit Ratings on Liquidity and Collateral Obligations -
Ratings Triggers - In March 2026, Standard & Poor’s Ratings Services changed certain IPL credit ratings, which are not expected to have a material impact on Alliant Energy’s and IPL’s liquidity or collateral obligations. Alliant Energy’s, IPL’s and WPL’s current credit ratings and outlooks are as follows:

Standard & Poor’s Ratings Services
Alliant Energy: Corporate/issuer BBB+
Commercial paper A-2
Senior unsecured long-term debt BBB
Outlook Stable
IPL: Corporate/issuer A-
Commercial paper A-2
Senior unsecured long-term debt A-
Outlook Stable
WPL: Corporate/issuer A-
Commercial paper A-2
Senior unsecured long-term debt A-
Outlook Stable

Off-Balance Sheet Arrangements and Certain Financial Commitments - A summary of Alliant Energy’s and IPL’s off-balance sheet arrangements and Alliant Energy’s, IPL’s and WPL’s contractual obligations is included in the 2025 Form 10-K and has not changed materially from the items reported in the 2025 Form 10-K , except for the items described in Notes 3 , 6 and 12 .

ITEM 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

Quantitative and Qualitative Disclosures About Market Risk are reported in the 2025 Form 10-K and have not changed materially.

ITEM 4. CONTROLS AND PROCEDURES

Alliant Energy’s, IPL’s and WPL’s management evaluated, with the participation of each of Alliant Energy’s, IPL’s and WPL’s Chief Executive Officer, Chief Financial Officer and Disclosure Committee, the effectiveness of the design and operation of Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures (as defined in Rule 13a-15(e) of the Securities Exchange Act of 1934, as amended) as of June 30, 2026 pursuant to the requirements of the Securities Exchange Act of 1934, as amended. Based on their evaluation, the Chief Executive Officer and the Chief Financial Officer concluded that Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures were effective as of the quarter ended June 30, 2026.

There was no change in Alliant Energy’s, IPL’s and WPL’s internal control over financial reporting that occurred during the quarter ended June 30, 2026 that has materially affected, or is reasonably likely to materially affect, Alliant Energy’s, IPL’s or WPL’s internal control over financial reporting.

PART II. OTHER INFORMATION

ITEM 1. LEGAL PROCEEDINGS

None. SEC regulations require Alliant Energy, IPL and WPL to disclose information about certain proceedings arising under federal, state or local environmental provisions when a governmental authority is a party to the proceedings and such proceedings involve potential monetary sanctions that Alliant Energy, IPL and WPL reasonably believe will exceed a specified threshold. Pursuant to the SEC regulations, Alliant Energy, IPL and WPL use a threshold of $1 million for purposes of determining whether disclosure of any such proceedings is required. Applying this threshold, there are no environmental matters to disclose for this period.

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ITEM 1A. RISK FACTORS

The risk factors described in Item 1A in the 2025 Form 10-K have not changed materially.

ITEM 2. UNREGISTERED SALES OF EQUITY SECURITIES AND USE OF PROCEEDS

A summary of Alliant Energy common stock repurchases for the quarter ended June 30, 2026 was as follows:

Total Number Average Price Total Number of Shares Maximum Number (or Approximate
of Shares Paid Per Purchased as Part of Dollar Value) of Shares That May
Period Purchased (a) Share Publicly Announced Plan Yet Be Purchased Under the Plan (a)
April 1 through April 30 5,201 $73.10 — N/A
May 1 through May 31 2,639 70.91 — N/A
June 1 through June 30 7 72.94 — N/A
7,847 72.36 —

(a) All shares were purchased on the open market and held in a rabbi trust under the Alliant Energy Deferred Compensation Plan. There is no limit on the number of shares of Alliant Energy common stock that may be held under the Deferred Compensation Plan, which currently does not have an expiration date.

ITEM 5. OTHER INFORMATION

During the quarter ended June 30, 2026, no director or officer of Alliant Energy, IPL or WPL adopted or terminated a Rule 10b5-1 trading arrangement or non-Rule 10b5-1 trading arrangement, as each term is defined in Item 408(a) of Regulation S-K .

Amended and Restated Bylaws

On July 29, 2026, the Board of Directors (the “Board”) of Alliant Energy Corporation (the “Company”) approved an amendment and restatement, effective July 31, 2026 (the “Amendment and Restatement”), of the Amended and Restated Bylaws of the Company, dated November 8, 2022 (the “Bylaws”).

The Amendment and Restatement amends Section 4.4 of the Bylaws to remove provisions relating to (i) the age following which directors are not eligible to be re-elected to the Board and (ii) the process by which a director must provide notice and tender a resignation to the Board following a change in employment, with such topics instead addressed within the Company’s Corporate Governance Guidelines, which are available on the Company’s investor website.

The Amendment and Restatement also amends Section 6.1 of the Bylaws to update the officers required to be elected by the Board to a specified list of officers identified in the Bylaws, together with any executive officers of the Company as defined by the rules and regulations of the Securities and Exchange Commission. Additionally, the Amendment and Restatement contains amendments to Section 6.3 and 6.6, in order to conform to the changes in Section 6.1.

The foregoing description of the Amendment and Restatement does not purport to be complete and is qualified in its entirety by reference to the full text of the Amended and Restated Bylaws, effective July 31, 2026, which is filed as Exhibit 3.1 to this Quarterly Report on Form 10-Q and is incorporated herein by reference.

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ITEM 6. EXHIBITS

The following Exhibits are filed herewith or incorporated herein by reference.

Exhibit Number Description
3.1 Amended and Restated Bylaws of Alliant Energy, effective July 31, 2026

3.2 Amended and Restated Bylaws of IPL, effective July 31, 2026

3.3 Amended and Restated Bylaws of WPL, effective July 31, 2026

31.1 Certification of the Chief Executive Officer for Alliant Energy

31.2 Certification of the Chief Financial Officer for Alliant Energy

31.3 Certification of the Chief Executive Officer for IPL

31.4 Certification of the Chief Financial Officer for IPL

31.5 Certification of the Chief Executive Officer for WPL

31.6 Certification of the Chief Financial Officer for WPL

32.1 Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for Alliant Energy

32.2 Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for IPL

32.3 Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for WPL

101.INS Inline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document
101.SCH Inline XBRL Taxonomy Extension Schema Document
101.CAL Inline XBRL Taxonomy Extension Calculation Linkbase Document
101.LAB Inline XBRL Taxonomy Extension Label Linkbase Document
101.PRE Inline XBRL Taxonomy Extension Presentation Linkbase Document
101.DEF Inline XBRL Taxonomy Extension Definition Linkbase Document
104 Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, Alliant Energy Corporation, Interstate Power and Light Company and Wisconsin Power and Light Company have each duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized on t he 31st day of July 2026.

ALLIANT ENERGY CORPORATION
Registrant

By: /s/ Dylan M. Syse
Chief Accounting Officer and Controller
Dylan M. Syse (Principal Accounting Officer and Authorized Signatory)

INTERSTATE POWER AND LIGHT COMPANY
Registrant

By: /s/ Dylan M. Syse
Chief Accounting Officer and Controller
Dylan M. Syse (Principal Accounting Officer and Authorized Signatory)

WISCONSIN POWER AND LIGHT COMPANY
Registrant

By: /s/ Dylan M. Syse
Chief Accounting Officer and Controller
Dylan M. Syse (Principal Accounting Officer and Authorized Signatory)

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