They're traditionally one of the most lucrative units of a major financial firm, fierce competitors for the ample fees buyout shops toss off. These elite financial sponsors groups generated at least $7.68 billion in global investment banking fees through M&A advisory, equity capital markets work and debt financing in the first half of 2011 alone, accounting for 19% of all the investment banking fees over that time, according to Dealogic. This constitutes a major rebound from a decade low in the first six months of 2009 and nearly equals the first half of 2006, the second-highest such period on record.

As Matthew Stopnik, the U.S. head of financial sponsors for UBS, says, "It's a loyal client base, and it's a great driver of opportunities across the platform, all different products, all different sectors."

The Deal magazine recently spent several months interviewing financial sponsors group heads to assess how their teams had reconstituted themselves after the financial crisis. In this relationship-driven world, major firms place a premium on continuity and ensuring that they have bankers with big Rolodexes and reputations in charge of these groups. The least senior managing director on Credit Suisse Group's financial sponsors team has been with the firm 13 years, for instance.

While the independent brands of three major firms were swallowed up in the turmoil of 2008, many teams and major talent survived intact. For example, J.P. Morgan Chase & Co. picked up its current co-head of financial sponsors, Larry Alletto, and several other members of the group from the old Bear Stearns Cos. Bank of America Corp. immediately shot up to the No. 1 ranking for fees in its sponsors business when it acquired Merrill Lynch & Co. And most strikingly, Barclays Capital, the investment banking division of Barclays plc, got nearly its entire sponsors team by absorbing the investment banking unit of Lehman Brothers Holdings Inc. after the firm's failure. Some of the Barclays team, including John Miller, head of global financial sponsors at the firm, not only come from Lehman but have been together since business school in the '90s.

These relatively small teams at the biggest banks hoard some of the most profitable deals around. J.P. Morgan, BofA and Goldman, Sachs & Co. ranked as the top three in FSG fees in the first half of the year, according to Freeman Consulting Services and Thomson Reuters. They collectively take in 30% of all fees paid by sponsors. "J.P. Morgan is still the 800-pound gorilla in the room," says one banker.

One of the most striking developments in the world of FSGs is the recent attention given to the middle market -- even at firms that used to harvest megabuyouts. Morgan Stanley, for instance, hired Joe Purcell out of J.P. Morgan last year to head up its middle-market effort. The average value of deals done by the top 10 firms dropped from $4.2 billion in 2006 to $597 million in 2008 before rebounding to $962 million in 2011 through June, according to Preqin Ltd.

"What's missing is the very, very large consortium leveraged buyouts, but the mix of buyouts remains," says J.P. Morgan's Alletto.

Midmarket-oriented teams are raising their profiles. In August Jorge Mora, in the sponsors group at UBS through 2008, accepted a position as head of the U.S. sponsors group at Macquarie Capital, which has made an aggressive push into private equity advisory. Shortly after Mora's move, London-based managing director James Seagrave defected from J.P. Morgan and David Luse left Bank of America Merrill Lynch to join as managing directors with the sponsors group at Jefferies & Co., which has doubled the size of its PE team over the past two years. Just last year, Lehman veteran Les Gorman joined as co-head of the expanding financial sponsors group at BMO Capital Markets; Lazard hired Fotis Hasiotis from BAML to co-head its European team advising PE firms; and Mark Epley left his post as global head of financial sponsors at Deutsche Bank AG, where he had worked for nine years, to head up Nomura Holdings Inc.'s FSG.

Despite their ubiquity, there are surprisingly few places where sponsor heads received their training: Most notably, nearly a dozen managing directors or sponsor heads stem from either investment bank Donaldson, Lufkin & Jenrette, acquired by Credit Suisse in August 2000, or its junk bond-pioneering predecessor, Drexel Burnham Lambert, which, after its demise in 1990, provided DLJ with much of its talent.

Alletto and Adam Sokoloff, head of Jefferies' financial sponsor group, worked at Drexel together. Stopnik's predecessor at UBS was Steve Smith, another Drexel alum who now runs UBS' restructuring department. Macquarie's Mora hails from DLJ, as does Moelis & Co. founder Ken Moelis (he started out at Drexel) and others in his sponsors group, which managed to grab 9.6% of the market share for advisory roles in PE-backed deals through August, according to Dealogic. Then there's Credit Suisse, whose team absorbed the DLJ DNA after the 2000 acquisition.

"At both First Boston and DLJ, the goal was to train people to be well-rounded bankers. That philosophy continues today at Credit Suisse," says Malcolm Price, Credit Suisse's current head of financial sponsors in North America. Brian Van Elslander, the head of FSG at Wells Fargo Secutiies LLC, came out of Credit Suisse in 2006.

When asked why being part of these teams made for such long careers, veteran PE bankers uniformly saw the resiliency of PE in tough times as vindication of the business model. "The combination of long-term or sticky money, patient capital structures and sound operational practices allowed [PE firms] to successfully manage through the crisis," says Citigroup Inc.'s head of the alternative investments group, Brad Coleman. Considering the tectonic shifts in the financial world over the past decade -- not to say in recent months -- that may be what they'll have to do again.