Mohamed El-Erian abruptly stepped down as chief executive of Pacific Investment Management Co, the giant asset-management firm that emerged as one of the winners of the global financial crisis but has recently been hit by waning investor taste for plain vanilla bonds.

El-Erian will leave in mid-March after seven years at the helm of Pimco, which manages $2 trillion as a unit of Germany's Allianz. He will remain on the German company's International Executive Committee and will advise on global economic and policy issues.