He was Chairman of Commonwealth Edison, Chicago’s electric utility.
It worked for Armand Hammer but his was a completely different gig. He raised capital in the West for Uncle Joe, and then he bought an energy company in California that he used to break the Seven Sisters' control of the oil business, which eventually statalized all oil everywhere (a very small slice of worldwide reserves remains in private ownership, the opposite of what obtained in 1935).
What did the chairmanship of a utility company do for Uncle Joe?