Yahoo co-founder Jerry Yang has left the company, the latest dramatic change at the top of the embattled Internet firm.

Yang, who was involved in both Yahoo's rise to Internet titan in the late 1990s and early 2000s and its fall from grace in the past six years, resigned from all his posts at the company.

Specifically, he quit his position on Yahoo's board and on the boards of Yahoo Japan and Alibaba Group Holding, the company said in a statement.

"My time at Yahoo, from its founding to the present, 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," Yang wrote in a letter to Board Chairman Roy Bostock.

Yang also said in the letter that he is "enthusiastic" about the recent appointment of former PayPal President Scott Thompson as Yahoo CEO and about the company's prospects for future success.

"It's sad, because Jerry has been such an institution in Silicon Valley for so long, but his exit gives Thompson the runway he needs to make decisions and not be second-guessed," said Charlene Li, an Altimeter Group analyst, in an interview.

Yang has been a towering figure at Yahoo, having been not only a co-founder but also CEO of the company. "It's hard to operate in the shadows of someone like that. This departure really frees Scott to start with even more of a clean slate," Li said.

Yang's exit may be the first of several others on the board, which has been criticised by shareholders and financial analysts who believe it is responsible for many of the company's troubles, said industry analyst Greg Sterling of Sterling Market Intelligence.

"Maybe Yang is the sacrificial lamb," he said in a phone interview. "There may be more board resignations and substitutions coming."

Gartner analyst Allen Weiner sees Yang's departure as a vote of confidence, to an extent, that Yahoo is strong enough to succeed in the new digital world without his guidance. "Given its future as a digital media company, Yang's lack of media expertise makes him somewhat of an unnecessary cog," Weiner said via email.

Regardless of the internal events that led to Yang's exit, it will definitely play to those outside as a sign that Yahoo is embarking on a new beginning under its new CEO, the analysts said.

"It's a very clear signal that this is a new page, that anything that happened in the past isn't necessarily the path they'll take in the future," Li said.

Added Weiner: "His departure could be a symbolic gesture to separate the company from its past as much as possible."