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Exhibit 99.1 News Release FOR IMMEDIATE RELEASE Alliant EnergyM Alliant Energy Corporation Corporate Headquarters 4902 North Biltmore Lane Madison , WI 53718-2148 www.alliantenergy.com Media Hotline : Investor Relations : ( 608 ) 458-4040 Zac Fields ( 319 ) 786-8146 ALLIANT ENERGY ANNOUNCES SECOND QUARTER 2021 RESULTS Second quarter earnings per share were $ 0.57 in 2021 versus $ 0.54 in 2020 With strong year - to - date results , currently tracking toward the upper half of 2021 earnings guidance range of $ 2.50 to $ 2.64 MADISON , Wis . - August 5 , 2021 - Alliant Energy Corporation ( NASDAQ : LNT ) today announced U.S. generally accepted accounting principles ( GAAP ) consolidated unaudited earnings per share ( EPS ) for the three months ended June 30 as follows : Utilities and Corporate Services American Transmission Company ( ATC ) Holdings Non - utility and Parent Alliant Energy Consolidated GAAP EPS 2021 2020 $ 0.51 $ 0.48 0.03 0.04 0.03 0.02 $ 0.57 $ 0.54 " Our purpose - driven strategy has once again delivered solid financial and operating results , " said John Larsen , Alliant Energy Chair , President and CEO . " We recently hosted an ESG Investor Day , showcasing our Corporate Responsibility Report and highlighting our position as a leading utility in the renewable energy transition . We are pleased to share that solid results through the first half of the year have us currently tracking toward the upper half of our 2021 earnings guidance . " Utilities and Corporate Services - Alliant Energy's Utilities and Alliant Energy Corporate Services , Inc. ( Corporate Services ) operations generated $ 0.51 per share of GAAP EPS in the second quarter of 2021 , which was $ 0.03 per share higher than the second quarter of 2020. The primary drivers of higher EPS were higher earnings resulting from IPL's and WPL's increasing rate base , as well as warmer temperature impacts on electric sales for the quarter . These items were partially offset by higher depreciation expense and lower allowance for funds used during construction . Details regarding GAAP EPS variances between the second quarters of 2021 and 2020 for Alliant Energy are as follows : Higher revenue requirements primarily due to increasing rate base Estimated temperature impact on retail electric and gas sales Higher depreciation expense Lower allowance for funds used during construction Higher WPL retail electric fuel - related costs , net of recoveries Other Total 1 Variance $ 0.10 0.03 ( 0.03 ) ( 0.03 ) ( 0.02 ) ( 0.02 ) $ 0.03