One private equity executive who describes himself as having a lot of respect for Lee and says he has played golf with him declined to comment about Lee's scorekeeping. When pressed, he finally added, "Look -- he's a competitive guy and he likes to win."

Maybe it is this unassailable optimism that gives Lee the will to hang around for the next cycle, when he can once again bring in huge fees, even as many younger bankers are calling it quits. Certainly, big-name clients like Josh Harris, a partner at Apollo Management hope he's sticking around.

Harris describes Lee emailing him after a disagreement emerged the night before Apollo was to sign a $3.4 billion deal with GE to buy its silicon and quartz business in 2006.

" I think he called me 1 a.m., 1:30 a.m., 2 a.m., 2:30 a.m., 3 a.m., 3:30 a.m. -- literally," says Harris, who eventually unplugged his phones and woke to about 15 email messages from Lee.

"He is willing to throw his body to a different extent against getting a problem resolved in a deal," Harris says. "There aren't very many people like that, who are also of his stature and kind of success and wealth. Usually when you're at that level you don't do that."

But private equity, Lee's bread and butter, is likely to be an increasingly less prominent focus at JPMorgan, according to Doug Braunstein, JPMorgan's head of America's Investment Banking. In an interview last week on CNBC, Braunstein presented the private equity boom as a highly unusual period that was unlikely to repeat itself any time soon. He said private equity firms accounted for nearly a third of M&A activity in 2006-2007, a sharp increase from the 5% to 10% of the market they have represented in normal times.

"Financial sponsors will be an important component of the market, but it really will be strategic acquisitions that drive the market, which is what they've done for 17 of the last 20 years," Braunstein said on CNBC.

What that means for Lee remains to be seen.

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