Bain Capital, the US private equity firm, is set to make a large but long-awaited profit from its sale of Sealy, the world's largest mattress maker, to KKR, a rival buy-out firm, in a deal worth up to $1.5bn.

Bain, which led a consortium of other investors, has taken seven years to exit its investment in Sealy. It bought a majority stake in Sealy in 1997 in a deal that then valued the company at roughly $800m. Private equity companies typically try to sell companies they invest in within three to five years.