Alliant Energy Corp
A regulated utility holding company that delivers electricity and natural gas to roughly a million and a half homes and businesses across Iowa and Wisconsin through its two main units, Interstate Power and Light and Wisconsin Power and Light. The company was born in 1998 when three regional utilities merged, and it took the name "Alliant" the next year as a play on "alliance" — a nod to the three-way partnership that created it. Its roots stretch back to utilities incorporated in the 1920s, and it also holds a stake in a transmission-only company and a wind farm in Oklahoma.