Alliant Energy

Overview

Alliant Energy is a regulated, investor-owned public utility holding company that provides electric and natural gas services in the Midwest through two public utility subsidiaries: Interstate Power and Light Company (IPL) in Iowa and Wisconsin Public Service Corporation (WPL) in Wisconsin. Other units include Corporate Services and AEF (Alliant Energy’s non-utility holdings).

Key facts and figures (as of 2025, unless noted)

Subsidiaries and roles

• IPL: Public utility providing electric generation and distribution and natural gas distribution in Iowa; serves wholesale electric customers in Illinois and Iowa.
• WPL: Public utility providing electric generation and distribution and natural gas distribution in Wisconsin; serves wholesale electric customers in Wisconsin.
• Corporate Services: Provides administrative services for Alliant Energy, IPL, WPL, and AEF.
• AEF: Non-utility holdings, including ATC-related interests, corporate venture investments, wind/non-utility generation, Travero (logistics), and Development-ready Sites.

Customers

• Consolidated scope (Alliant Energy, IPL, WPL): approximately 1,010,000 electric customers and 435,000 natural gas customers.
• As of December 31, 2025:
  • IPL: ~505,000 electric customers; ~230,000 natural gas customers.
  • WPL: ~505,000 electric customers; ~205,000 natural gas customers.

Employees

• Alliant Energy: 2,948 total employees; 1,705 in bargaining units (58% of all employees).
• IPL: 1,003 total employees; 739 bargaining unit employees (74%).
• WPL: 992 total employees; 853 bargaining unit employees (86%).

Revenues (2025)

• Alliant Energy (consolidated):
  • Electric revenues: 3,697 million
  • Gas revenues: 525 million
  • Total consolidated revenues: 4,222 million
• IPL:
  • Electric revenues: 1,896 million
  • Gas revenues: 265 million
  • Total IPL revenues: 2,161 million
• WPL:
  • Electric revenues: 1,801 million
  • Gas revenues: 260 million
  • Total WPL revenues: 2,061 million

Generation capacity (as of Dec 31, 2025)

• IPL total in-service generating capacity: 4,274 MW
  • Major fuel/generation categories include coal, gas, wind, solar, and energy storage (examples: coal 711 MW; gas 1,655 MW; wind 1,302 MW; solar 426 MW; energy storage 108 MW).
• WPL total in-service generating capacity: 4,166 MW
  • Major fuel/generation categories include gas, coal, wind, solar, hydro, and energy storage (examples: gas 1,380 MW; coal 1,001 MW; wind 480 MW; solar 1,102 MW; hydro 19 MW; energy storage 184 MW).

Operational scope

• IPL and WPL provide electric and natural gas utility services in their respective states and operate within regulatory frameworks (Iowa Utilities Board for IPL; Wisconsin Public Service Commission for WPL).
• Both companies participate in MISO markets for wholesale energy and ancillary services.
• IPL and WPL use owned electric generating units (EGUs), power purchase agreements (PPAs), and market purchases to meet customer demand. Transmission services are provided by ITC (IPL) and ATC (WPL), both FERC-regulated.

Steam operations

• IPL exited the steam business after December 31, 2025. Prairie Creek steam customers were under contract through 2025.

Notes

• Figures reflect the period ending December 31, 2025 and are drawn from 2025 disclosures.