San Francisco  - Jerry Yang, who helped kick start the internet revolution in 1995 as co-founder of web portal Yahoo, is stepping down as the company's chief executive.

The announcement by the ailing internet giant came after months of falling revenue, fierce proxy battles and a series of botched negotiations that scuttled what now seems to have been an exceedingly generous buyout offer from Microsoft.

Yang's alternative plan - an ad alliance with Google - was scuttled last week after strenuous objections from antitrust regulators.

Yahoo said that the search for a successor had already started and that Yang will leave after his replacement is found.

"Jerry and the board have had an ongoing dialogue about succession timing, and we all agree that now is the right time to make the transition to a new CEO who can take the company to the next level," Yahoo Chairman Roy Bostock said in a statement.

Yang, 40, took over at the company's helm last year as Yahoo fell behind web-search powerhouse Google in attracting users and advertisers to its properties. He soon faced fierce criticism for rejecting a 47.5-billion-dollar takeover by Microsoft, in a deal that would have valued Yahoo at almost three times what it is worth today.

Microsoft's offer was worth 33 dollars per share, while Yahoo traded at just 10.63 dollars per share at the close of Monday trading. Following the announcement shares jumped to 11.10 dollars, largely on speculation that Yang's departure increases the likelihood of a deal with Microsoft.

"Having set Yahoo on a new, more open path, the time is right for me to transition the CEO role and our global talent to a new leader," said Yang.

"I will continue to focus on global strategy and to do everything I can to help Yahoo realize its full potential and enhance its leading culture of technology and product excellence and innovation." (dpa)