Before a clandestine video of a Mitt Romney fund-raiser at his Florida home became national news, private-equity baron Marc J. Leder may have been best known in Massachusetts as the man who deprived almost half the state of its Fribbles.

The buyout firm that Leder cochairs, Sun Capital, purchased Friendly’s, the New England restaurant chain, in 2007. But instead of the long-ailing company turning around, Friendly’s briefly went into bankrupcy last year, leading to the closing of about 40 percent of its Massachusetts locations.