ALLIANT ENERGY CORP
Ticker: LNTUtilitiesElectric, Gas & WaterS&P 500The business
Alliant Energy Corporation (NASDAQ: LNT) operates as a regulated investor-owned public utility holding company headquartered in Madison, Wisconsin, with its primary business conducted through two wholly-owned public utility subsidiaries: Interstate Power and Light Company and Wisconsin Power and Light Company. The company maintains its corporate website at www.alliantenergy.com.
Alliant Energy's core business focuses on providing regulated electric and natural gas utility services to approximately 1.01 million electric customers and approximately 435,000 natural gas customers across the Midwest. Interstate Power and Light Company serves approximately 505,000 electric and 230,000 natural gas retail customers in Iowa, while also selling electricity to wholesale customers in Illinois and Iowa. Wisconsin Power and Light Company serves approximately 505,000 electric and 205,000 natural gas retail customers in Wisconsin, with wholesale electricity sales to customers in Wisconsin.
The company operates as a vertically integrated utility, engaged in the generation, transmission, and distribution of electricity and the distribution and transportation of natural gas. Alliant Energy's customer base spans diverse industries including farming, agriculture, industrial manufacturing, chemical production including ethanol, pipeline transportation, packaging, food processing, and data centers.
Beyond its core utility operations, Alliant Energy maintains non-utility holdings organized under Alliant Energy Finance, LLC, which manages a portfolio of subsidiaries and investments. These include a 16 percent ownership interest in American Transmission Company, a transmission-only company, a 50 percent cash equity ownership interest in a 225 megawatt non-utility wind farm in Oklahoma, and Travero, a supply chain solutions company providing short-line rail freight service, Mississippi River barge and rail terminal operations, and freight brokerage services.
As of December 31, 2025, Alliant Energy employed approximately 2,948 full- and part-time employees across its operations, with 58 percent covered by collective bargaining agreements. The company is subject to comprehensive regulation by the Federal Energy Regulatory Commission, the Iowa Utilities Commission, and the Public Service Commission of Wisconsin, governing retail utility rates, service standards, environmental compliance, and capital investments.
- Sector
- Utilities
- Industry
- Electric, Gas & Water
- HQ
- MADISON, WI
- FY end
- 12-31
- CIK
- 352541
- SIC
- 4931
Ownership
Who holds ALLIANT ENERGY CORP — across funds, superinvestors and bonds · N-PORT 2026Q2 · 13F 2026-06-30
Top fund holders
| Fund | % of fund | Value |
|---|---|---|
| VANGUARD TOTAL STOCK MARKET INDEX FUND VTI · VANGUARD INDEX FUNDS | 0.03% | $625.38M |
| Janus Henderson Enterprise Fund JAENX · Janus Investment Fund | 2.36% | $527.58M |
| VANGUARD 500 INDEX FUND VOO · VANGUARD INDEX FUNDS | 0.03% | $510.38M |
| Victory Sycamore Established Value Fund VETAX · Victory Portfolios | 2.10% | $324.23M |
| State Street(R) Utilities Select Sector SPDR(R) ETF XLU · SELECT SECTOR SPDR TRUST | 1.39% | $320.62M |
Bonds held by funds
Funds report holding 28 issues of ALLIANT ENERGY CORP's debt, $1.27B at fund-held market value — what funds hold, not the company's debt outstanding. Weighted-average coupon 4.25%, maturing 2027–2056.
| Issue | Coupon | Matures | Funds | Fund-held |
|---|---|---|---|---|
| ALLIANT ENERGY | 5.750%Variable | 2056-04-01 | 106 | $210.37M |
| Interstate Power and Light Co. | 5.600% | 2035-06-29 | 56 | $118.60M |
| Wisconsin Power and Light Co | 3.950% | 2032-09-01 | 48 | $114.85M |
| WISCONSIN P&L | 5.380% | 2034-03-30 | 50 | $93.00M |
| Interstate Power and Light Co | 4.100% | 2028-09-26 | 52 | $83.13M |
| INTERSTATE P&L | 2.300% | 2030-06-01 | 49 | $78.20M |
| WISCONSIN POWER AND LIGHT CO | 4.950% | 2033-04-01 | 42 | $55.41M |
| LNT 3.5 09/30/49 | 3.500% | 2049-09-30 | 30 | $55.11M |
| Alliant Energy Corp | 3.250% | 2028-05-30 | 15 | $54.28M |
| Interstate Power and Light Co. | 4.950% | 2034-09-30 | 46 | $51.03M |
The 10 largest by fund-held value, of 28.
Fund ownership counts N-PORT filers only, so it is a floor rather than a census — pensions, insurers and direct holders are not visible here, and the remainder is not “held by individuals”.
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