Nazem, who joined the company in 1996, said in a statement on Yahoo's Web site that he intends to retire. His last day is scheduled for June 8.
The move comes six months after Nazem, 45, was named head of one of the portal's three main business units. Shares of Yahoo fell to $28.24 in after-hours trading from a close of $28.38 on the Nasdaq stock exchange.
Yahoo is undergoing a wave of change as it tries to make up ground on archrival Google. Last December, Yahoo's chief operating officer and the head of its entertainment group left as part of an executive shakeup. Google has eclipsed Yahoo in search and advertising. Yahoo's profits slid 11 percent in the first quarter from the year prior. The company's revenue for that period was $1.67 billion, less than half Google's $3.66 billion.
A new advertising platform launched in February is supposed to help Yahoo profit more from search, and Nazem said he was waiting to retire until after the system was operating.
Jerry Yang, Yahoo's co-founder, will replace Nazem on an interim basis.
