Russell SimmonsAlthough this mogul towers over the music industry from the top of his Def Jam empire, Russell Simmons still has professional regrets and he's dishing on them in his new book, 'Super Rich: A Guide to Having It All."

His biggest regret? "Losing the Beastie Boys," he writes in an article on his website, GlobalGrind, timed with today's release of the boys' latest album, 'Hot Sauce Committee Part Two.'

Simmons and his partner, Rick Rubin, first signed the young trio to their label, Def Jam Records, and in 1986 produced their album, 'License to Ill,' to skyrocketing numbers -- making history as the first hip-hop album to land at number one on the Billboard charts. But the union between Simmons and the group wasn't all hit records and their professional relationship began to suffer before the Beastie Boys soon left Def Jam for Capitol Records.