Yahoo chief executive Carol Bartz has been fired after two-and-a-half years in the job.
The company said in a statement that Ms Bartz was removed by the board of directors, effective immediately.
Chief financial officer Tim Morse will take over as as interim chief executive.
The BBC reports Yahoo has been struggling to increase its market share as it faces increased competition from rivals such as Google and Facebook.
Ms Bartz was hired to run Yahoo in early 2009, taking over from co-founder Jerry Yang.
Yahoo shares jumped more than 6% in after-hours trading after news of the firing broke on a Wall Street Journal website, which quoted an email from Ms Bartz to Yahoo personnel.
However, technology consultant Shelly Palmer says the dismissal is too little, too late.