Jerry Yang, who co-founded Yahoo!, was once its CEO, and has since served on its board of directors, has formally announced his resignation from the company.

The 43-year-old has been under tough scrutiny as his once dominant Internet portal has floundered in recent years. His exit comes after Yahoo! installed new CEO Scott Thompson just two weeks ago.

"The time has come for me to pursue other interests outside of Yahoo," Yang said in a statement.

 While CEO of Yahoo! in 2007 and 2008, Yang famously rejected a buyout offer from Microsoft for more than $45 billion. He has been criticized for the decision ever since. Upon news of his departure, Yahoo!'s stock price rose 3.5 percent.

The company is on a long road that it hopes will bring renewal. Prior to Thompson's hiring, previous CEO Carol Bartz was unceremoniously canned last year.

[via WSJ]