Yahoo co-founder Jerry Yang has resigned from the internet company.

Yang, who started the firm in 1995 with David Filo, has stepped down from all his positions including his seat on the board of directors. The move comes just weeks after Yahoo appointed a new CEO, Scott Thompson, after Carol Bartz was fired by the firm in September last year. Yang currently owns 3.69 percent of all Yahoo's shares.

Yahoo did not offer any explanations as to why Yang resigned. Instead, in a letter to employees, which was obtained by Reuters, Thompson said: "I am grateful for the support and warm welcome Jerry provided me in my early days here".

"His insights and perspective were invaluable, helping me to dig deeper, more quickly than I could have on my own, into some of the key elements of the company and how it operates."

In a letter Yahoo Chairman Roy Bostock, Yang said his time at the tech giant has "encompassed some of the most exciting and rewarding experiences of my life".

"However, the time has come for me to pursue other interests outside of Yahoo."

He also said he is "enthusiastic" about Thompson's appointment and the future of the company.

According to Reuters one former Yahoo employee said many at the tech firm think Yang "holds up innovation there with old ideas and (is) slow to decide and that he's not an innovator himself for being at such a high level.

"People have very high expectations for founders. Everyone wants a Steve Jobs," the employee said.