Recent buyout fundraising: $13 billion

Description: Spun off from the consulting firm Bain & Co. in 1984, these Boston-based dealmakers fancy themselves the intellectuals of the private-equity world, and their investors are drawn more from university endowments than from pension funds. CEO-less since Mitt Romney left in 1999 to run for governor, Bain's 26 partners work as equals, although there are standouts, like Steve Pagliuca (Bain's top partner on the HCA megadeal), Joshua Bekenstein (on the board at Yale's business school), and Mark Nunnelly (a key brain behind the Domino's turnaround).

However, this collective intelligence doesn't come cheap: Bain charges a 30 percent fee to its limited partners, vs. the standard 20 percent rate. And despite a hot 2006, in which it took Outback Steakhouse private for $3.2 billion, it is still smarting from accusations that a $121 million dividend it earned in 2002 for buying out KB Toys sent the company into Chapter 11 two years later. It has also been popping up in club deals, for which they've created a special co-investment fund with a 20 percent rate.

Boldface advisors: Jonathan Zhu, the former CEO of Morgan Stanley China, recently joined to help spend Bain's new $1 billion Asia fund.

Fun fact: Pagliuca is now part owner of the Boston Celtics.