Long hours and a frequently fractious relationship with Pimco's founder Bill Gross prompted Mohamed El-Erian's resignation as chief executive of the world's largest bond house, say people familiar with the matter.
Mr. El-Erian often sparred with the company's founder over strategy, in a workplace that insiders say rivals any investment bank for fierce arguments and a hard-charging culture. There was no single argument with Mr. Gross that triggered the move, the people said.
(Read more: Pimco CEOEl-Erian resigns effective March: WSJ)
Mohamed El-ErianEmile Wamsteker | Bloomberg | Getty Images
His resignation on Tuesday evening came as a shock to those both inside and outside of Pimco but his plan to leave had been known to a small group of senior executives for several months, the people said.
Mr. El-Erian, whose day in the office starts about 4:15 a.m. in Newport Beach, California, told colleagues he wanted to write a book and spend more time with his family.
He said he was looking for a "third career" after spending 15 years at the International Monetary Fund and 17 years in investment management, both at Pimco – which has $2 trillion of assets under management – and a two-year stint managing Harvard University's endowment.
The resignation was not related to Pimco's recently lackluster performance, the people said. Its flagship Total Return Fund suffered a record $41.1 billion of outflows in 2013 after a botched bet on the direction of US Treasurys led to its worst annual performance in almost two decades.
(Read more: World in 2014 isbetter…but not good enough: El-Erian)
