Mohamed El-Erian unexpectedly resigned from his post as chief executive and co-chief investment officer of global investment management firm Pimco on Tuesday, the firm said in a statement.
El-Erian will leave the firm in March and will remain a member of parent company Allianz's international executive committee. He will also serve as an advisor on global economic and policy issues.
William H. Gross will continue to serve as chief investment officer, the firm said in a statement.
"I have been extremely honored and fortunate to work alongside Bill Gross, who is one of the very best investors in the world," El-Erian said in a statement. "I have also been amazingly privileged to work with the most talented group of professionals in the investment management industry."
On Pimco's Twitter feed, Gross, Pimco's founder, wrote: "Pimco's fully engaged. Batteries 110% charged. I'm ready to go for another 40 years!"
El-Erian rejoined the Newport Beach-based firm in 2007 after serving for two years as president of Harvard Management Co. He joined the firm in 1999 as a member of its portfolio management and investment strategy group.
Pimco is one of the largest global investment managers, with nearly $2 trillion in assets under management as of the end of September, according to its website.
El-Erian, the son of an Egyptian diplomat, earned a doctorate in economics from Oxford University, then spent 15 years at the International Monetary Fund, a financial advisor and lender to developing nations.
Pimco recruited him in 1999, when the firm was looking for someone to boost its stake in high-yielding, high-risk bonds of emerging-market nations such as Brazil, Russia and Mexico. As head of Pimco’s emerging-markets debt team, he became the world's single biggest investor in bonds of developing countries, and like Gross was monitored closely by investors around the world for his outspoken economic and market views.
He left Pimco in 2005 to oversee Harvard University's $26-billion endowment portfolio, the largest such university fund. But he returned in 2007.
The firm on Tuesday also announced other top leadership changes.
Douglas Hodge, Pimco's current chief operating officer, has been appointed chief executive. Jay Jacobs, a managing director in Newport Beach, has been named president. Craig Dawson has been named head of strategic business management.
On the investment side, Andrew Balls and Daniel Ivascyn have both been appointed as deputy chief investment officers. Balls is a managing director in Pimco's London office. Ivascyn is a managing director in the Newport Beach office.
[Updated 2:35 p.m. Pacific time Jan. 21: This post has been updated to include El-Erian's biographical information, Gross' Twitter comment and additional leadership changes.]