Profile · Beloit, Wisconsin
Diane Marie Hendricks (née Smith)
ABC Supply co-founder and chair; Beloit business base, lives in Afton (raised Osseo)
$21.7 billion
Diane Marie Hendricks co-founded ABC Supply in Beloit in 1982, has chaired the company since 2007, and is the city’s living fortune—Forbes listing her among America’s richest self-made women. She lives in Afton, between Beloit and Janesville. She was not born in Beloit. One of nine sisters on a dairy farm in Osseo, she decided at ten she would not marry a farmer. Pregnant at seventeen, she finished Osseo-Fairchild at home, assembled pens at Parker Pen in Janesville, sold custom houses, and in 1975 married Ken Hendricks—a Janesville roofer’s son and high-school dropout already running a five-hundred-man crew. In 1982 they liquidated that firm and bought three failing Bird & Sons yards in Muskegon, Belleville, and Springfield. Headquarters: Beloit. First-year sales were $4.5 million; ABC topped the Inc. 500 in 1986. She ran the books and the bank. He climbed the jobs. On the night of December 20, 2007, Ken fell through a tarp covering an opening in a subfloor over their Afton garage and died the next morning on a Rockford operating table. Forbes had just listed him at $3.5 billion. Diane kept ABC, bought Bradco in 2010 and L&W Supply in 2016, and grew the firm past nine hundred branches and $20.2 billion in 2025 revenue. She poured millions into the old Fairbanks-Morse floors, put her name on a ballpark, and filmed Betting on Beloit with her daughter. Forbes put her personal fortune at $21.7 billion as of June 3, 2026. The farm was Osseo; the death was Afton; the fortune is Beloit.