Mauboussin is well-known for his work on questions like the relative roles of skill and luck. He gained stature as the chief investment strategist since 2004 of Legg Mason Capital Management, the value investing unit chaired by famed fund manager Bill Miller.

But Miller's performance fell off in recent years, one of a number of problems that have held back Baltimore-based Legg Mason's overall growth and led to the company's ongoing efforts to find a new chief executive.

Last year Miller stepped back from running the largest fund, Value Trust, now managed by Sam Peters. Peters also took over as chief investment officer of the unit.

Neither Mauboussin nor Peters immediately returned messages. Legg Mason spokeswoman Mary Athridge said Mauboussin is promoting his new book, "The Success Equation: Untangling Skill and Luck in Business, Sports, and Investing," and may start a new role with another firm.

Mauboussin is still listed as an adjunct professor at Columbia University's business school and as chair of the board of the Santa Fe Institute, according to their websites.

(Reporting By Ross Kerber; Editing by Leslie Adler)