8 of 15
Apollo co-founder Leon Black
2008 Rank: 8
2007 Rank: 7
Recent buyout fundraising: $12.5 billion

In a letter to his limited partners in February, co-founder Leon Black reminded them that the company's first two funds were started in the leveraged-buyout slump of the early 1990s and went on to return 37% a year. In other words, the Apollo co-founder likes distressed assets--even if the debt he's devouring is a result of Apollo's own deals, such as the one in 2006 for Harrah's, which closed earlier this year.

In April, Apollo filed with the SEC to list on the New York Stock Exchange. It's not your average IPO. Last year, Apollo shares began trading on a private Goldman Sachs exchange for institutional investors. As part of its agreement with the new shareholders last August, Apollo promised that within 240 days of the offering, those shares could begin to trade publicly. It's unclear how liquid the stock will be.

Headwind issue: Linens 'n Things, which lost $242 million last year, filed for bankruptcy earlier this month. Apollo took the retailer private in 2005.

Worth noting: Tom Petty played at Leon Black's 56th-birthday party last summer in East Hampton, N .Y.

NEXT: Providence Equity Partners
Last updated July 28 2008: 4:28 PM ET
Source: Rankings are based on a firm's most recently raised buyout fund(s). Fortune looked at data from Capital IQ, institutional investors, and the companies themselves to determine the size of the most recently raised buyout funds. For some firms that means a fund that was raised in 2007; for others it might be 2006. Whatever the date, the most recent fund was the one we counted. In the case of companies that raise multiple funds simultaneously as opposed to raising a single fund at a time, we chose to count only those private equity funds that were not raised in public markets and that were earmarked for buyouts (as opposed to investments in debt, venture capital, or other ventures).
The year of the vulture The private equity firms that will thrive in the year ahead are those that know how to profit from others' misfortunes. (more)
35 largest U.S. private companies Some of the biggest names in business operate outside the public markets. Here's a look at the top players. (more)
10 private-equity deals gone bust When the liquidity is flowing like wine, every deal looks like a perfect ten. But a lot can - and has - gone wrong. (more)