After 18 months on the job, Fred Amoroso won't seek re-election to Yahoo!'s (NASDAQ: YHOO) board of directors. He'll continue to serve as a director through the company's annual meeting on June 25 but has resigned as chairman. Former eBay executive Maynard Webb Jr. has assumed the role on an interim basis, Yahoo! said in a press release.

"Fred has been a wonderful chairman for Yahoo! over the past year, and I'm personally grateful for his trust and guidance as I took on the role as Yahoo! CEO," said Yahoo! CEO Marissa Mayer.  "Fred's mentorship and perspective has proved truly valuable to me in my first few months here at Yahoo!"

Amoroso said his intent was always to serve in a transitional role:

"When I took the position as chairman, I told the board that my intention was to serve for one year, in order to help Yahoo! during a critical time of transformation. In that time, Yahoo! hired a great new CEO, brought on a fantastic management team, revitalized the employee base, and has begun to release top notch new products. "

Yahoo! will have 10 board members following Amoroso's departure. The company hasn't announced whether it intends to fill his seat.