1. The Blackstone Group
Recent buyout fundraising: $23 billion

Description: Since opening its doors with $400,000 in 1985, Blackstone has become known for sharp elbows and sharper deals. Witness its $3.8 billion buyout of Celanese in 2004: The firm put in $650 million in equity and almost immediately recouped $500 million with a junkbond offering. Or the way it unloaded $13 billion worth of buildings in its recent $38.9 billion buyout of Equity Office Partners before the ink was dry on the deal. As a hedge against a cyclical downturn in private equity, co-founder and CEO Steve A. Schwarzman has diversified the firm into hedge funds, distressed debt, asset management, and oh, yes, real estate. Moreover, the 60-year-old designated CSFB alum Hamilton "Tony" James president and his de facto successor in 2004.

Boldface advisors: Former Treasury Secretary Paul O'Neill.

Fun Fact: Co-founder Pete Peterson counts Alan Greenspan and Henry Kravis as golf buddies.
2. Kohlberg Kravis Roberts & Co.
Recent buyout fundraising: $21.6 billion

Description: Known primarily as a pure private equity firm, KKR has bounced back from some of its 1990s missteps (Regal Cinemas, anyone?) and reduced its dependence on first cousins Henry Kravis and George Roberts, who founded the firm with their Bear Stearns mentor, Jerome Kohlberg, in 1976. The heart of the operation is an investment committee that meets every Monday. KKR dealmakers are divided into 11 industry groups, which focus on 100-day plans; there is also an internal consulting group called Capstone. The firm remains hot, thanks to an annual rate of return of roughly 27 percent and considerable dealmaking muscle.

Boldface advisors: The former group chairman of HSBC Holdings, Sir John Bond, is expected to help with deals in Asia. Ed Artzt, formerly of Procter & Gamble, George Fisher from Motorola, and General Jack Keane, former Army vice chief of staff, review the portfolio companies.

Fun fact: When the Menlo Park, Calif., office gets together for lunch, George Roberts likes to grill people with brainteasers.
3. The Carlyle Group
Recent buyout fundraising: $18.3 billion

Description: Characterized by a rival as the "Fidelity of private equity," Carlyle manages almost $55 billion in 48 funds across four disciplines: buyouts, venture and growth, real estate, and leveraged finance (it's also developing a multistrategy hedge fund). Founded in 1987 by William Conway Jr., Dan D'Aniello, and David Rubenstein, among others (and named after the New York City hotel), the firm has caught heat in the past for managing money from the bin Laden family and reportedly profiting from defense-related deals (which have never accounted for more than 1 percent of its total).

Lately the massive 750-person firm has been known for its global reach, with 27 offices from New York City to Mumbai to Tokyo, plus portfolio companies employing more than 200,000 people and generating $68 billion in revenues. While calling its dealmaking style conservative, Carlyle, based in Washington, D.C., still boasts an average annual return of 34 percent. In 2001, Calpers bought a 5.5 percent stake in the firm.

Boldface advisors: Carlyle has swapped politicos like George H.W. Bush for business leaders, including its chairman, Louis Gerstner Jr., the former IBM chairman and CEO.

Fun fact: Rubenstein and his wife met while working in the Carter administration.
4. Texas Pacific Group
Recent buyout fundraising: $15.2 billion

Description: TPG's first major deal remains one of its signatures - the nervy turnaround of Continental Airlines. In 1993, TPG purchased the twice-bankrupt company and later sold its stake for ten times its original investment. The private-equity firm stepped into the airline industry again with its $8.7 billion buyout of Qantas last year. That helped TPG set a record for participating in the biggest dollar amount of deals ever done in a single year - $101 billion. Co-founder David Bonderman works out of Fort Worth, and fellow co-founder Jim Coulter is based in San Francisco. TPG is picking up steam in Asia, where it operates seven offices.

Boldface advisors: Former Air France chairman Bernard Attali and Leonard Schaeffer, the former CEO of WellPoint Health Networks.

Fun fact: Bonderman does not do e-mail. Instead, his secretaries fax him the messages, and he dictates his responses.
5. Bain Capital
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.
6. Providence Equity Partners
Recent buyout fundraising: $11 billion

Description: When it opened in 1990, Providence was a quiet niche player that made big money on small media and telco deals. Fellow buyout firms took notice when Providence invested $63 million in VoiceStream Wireless (later renamed T-Mobile) in 1992, then sold it to Deutsche Telekom in 2000 for 19 times its investment. Providence has been on a roll - its reported rate of return is 70 percent. A nonstop cash influx and new offices in New Delhi and Hong Kong should calm limited partners concerned about smaller stakes in pricier club deals and rising multiples in the firm's sectors in the U.S.

Boldface advisors: Former FCC chairman Michael Powell.

Fun fact: Rhode Island-based CEO Jonathan Nelson takes the firm on an annual ski trip to Alta, Utah.
7. Apollo Advisors
Recent buyout fundraising: $10.1 billion

Description: Apollo's founder and chairman, Leon Black, served up a double shot of dealmaking in December: In the same week he acquired Realogy, owner of Coldwell Banker and Century 21, for $9 billion, followed by a $27.4 billion deal to purchase Harrah's Entertainment together with Texas Pacific Group. The latter club deal was an exception, because the firm, whose name derives from the Greek god of light and healing, normally works alone. Black, who spent the 1980s running mergers and acquisitions at Drexel Burnham Lambert, is a master of labyrinthine debt financing. And his ability to heal broken companies has resulted in compound annual returns greater than 40 percent since the firm's inception in 1990. Some 90 percent of Apollo's investments have generated positive returns.

Boldface advisors: Adam Aron, former CEO of Vail Resorts. He built the mountain into the pound sterling of ski towns.

Fun fact: Apollo's penchant for distressed assets extends to office space. Its headquarters, which have unobstructed views of New York City's Central Park, are located in the former digs of Tyco.
8. Warburg Pincus
Recent buyout fundraising: $9.2 billion

Description: This hoary firm traces its roots to 1966, when E.M. Warburg & Co., an investment-banking and private investment counseling firm founded in 1939, joined forces with Lionel I. Pincus & Co., a venture capital firm. Warburg Pincus built its reputation by restructuring Mellon Bank in the 1980s. More recently it has joined club deals, like Aramark in 2006, but has otherwise stayed away from the mega-takeovers. It excels at what might be described as the venture buyout: takeovers for less than $1 billion of smaller, younger, fast-growing companies, which it holds for several years.

Recently the firm's best work has been in China and India. The biggest hit in India so far is Bharti Airtel, the country's largest cellular operator, in which Warburg bought a controlling stake for $337 million starting in 1999 and sold last year for $1.9 billion. The next big cashout may be WNS Holdings, a Mumbai-based IT outsourcer for which Warburg sold shares on the NYSE in July 2004. Last year Warburg closed a $1.2 billion real estate fund - about 60 percent of which is slated for buyouts in Asia.

Boldface advisors: Former Bank of America CEO David Coulter.

Fun fact: Warburg flies all of its investment professionals in six countries to the Waldorf-Astoria in New York City each year for an annual meeting.
9. Cerberus
Recent Buyout Fund Raising: $8 billion

Description: Steven Feinberg, another Drexel Burnham Lambert alumnus, founded Cerberus in 1992 and gained a reputation for using distressed debt the way a Sith lord wields a light saber. Even though Cerberus calls itself a "private investment firm" because it goes anywhere for returns, its deals for ANC Rental Corp. (parent of Alamo and National), Mervyns, and Air Canada place it squarely among private-equity heavyweights. The firm (named for Hades' three-headed dog) isn't afraid to snarl at top-tier firms and win, as it did when it stole GMAC and Albertsons from KKR.

Boldface advisors: Former Treasury Secretary John Snow is a chairman, and former Vice President Dan Quayle is the global chairman. Quayle's seat on the board of directors of Nippon Credit Bank (since renamed Aozora Bank) smoothed the way for Cerberus to take control of the Japanese bank.

Fun fact: Feinberg, a former captain of the Princeton tennis team, is an antielitist who works in a barebones office - albeit on Park Avenue - and drives a Chevy pickup truck.
10. Thomas H. Lee
Recent buyout fundraising: $7 billion

Description: Founder Tom Lee started his firm in 1974 with $150,000 - part inheritance, part loan from his brother. Lee moved to New York and left his Boston firm in 2005. Current senior partners Scott Sperling, Anthony DiNovi, and Scott Schoen continue to use his name. Lately Thomas H. Lee (the firm, not the man) has been hunting big game. Together with Bain Capital Partners and the Carlyle Group, Lee acquired Dunkin' Brands from Pernod Ricard for $2.4 billion in cash in March 2006. Again with Bain, Lee bid for Clear Channel Communications last fall. The price: $26.7 billion. With their most recent fund projected to close another $2 billion, expect to see Sperling, DiNovi, and Schoen continue to shake up the consumer, media, and business services sectors.

Boldface advisors: In October 2006 the firm hired media veteran Richard Bressler to lead its Strategic Resources Group. Bressler previously held positions at Viacom and was chairman and CEO of Time Warner Digital Media.

Fun fact: Some 30 out of 38 investment professionals are Harvard Business School alumni.

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