At the Jean-Georges restaurant Nougatine near New York's Central Park, Wachtell co-chair William Savitt received an offer in late May that would turn the legal world on its head. Savitt met with a Gibson Dunn partner, who dangled before him the once-unthinkable prospect of leaving Wachtell—the Wall Street firm where the elite corporate litigator had worked for two decades—in favor of a global juggernaut with some 2,200 lawyers and more than 20 offices around the world.

"Wouldn't it be fun to practice law together? Here, the sky's the limit for you," Orin Snyder, a litigator at Gibson Dunn who represents stars such as LeBron James, Bob Dylan and Lady Gaga, said over breakfast. It wasn't just fun Snyder offered—or even a multimillion-dollar raise that would bring Savitt's compensation to at least $20 million a year.