Investors bid up shares after reports that Jonathan Miller, AOL’s former chief executive, is attempting a private buyout of Yahoo.

Investors bid up shares after reports that Jonathan Miller, AOL’s former chief executive, is attempting a private buyout of Yahoo.

Carl Icahn, the billionaire investor, bought nearly seven million additional shares of Yahoo in a move likely to fuel speculation over Yahoo’s search for a new chief executive.

Steven A. Ballmer’s stance may force Yahoo’s next chief executive to find another way to revive the company’s profit.

Yahoo has a fundamental decision to make, say analysts. Does it want to remain an independent company, or should it sell some or all of itself to another Internet player?

Yahoo said Mr. Yang, who helped build the company into an Internet giant, would step down from his role as chief executive.

The comments by Steven A. Ballmer set off a 13 percent decline in Yahoo’s share price.

As Google turned 10 years old, Eric E. Schmidt, chief executive, looks ahead to the next 10 years.

Google chose to abandon the controversial plan after the Justice Department said it would file an antitrust suit to block it. Yahoo said it would have preferred to defend the deal in court.

The move, which came after antitrust regulators raised objections, leaves Yahoo scrambling for a plan for growth.