Semel had been given the push as the company lost ground to Google and AP thinks that Yang's return could foreshadow some drastic changes.
This includes partnerships with media and technology rivals or even a merger.
Yang co-founded the company 13 years ago with fellow Stanford University student David Filo.
Semel, was a long-time Hollywood studio executive who took charge of the company six years ago. He is credited with helping to stabilise the company's advertising and media businesses.
Lately he got into a bit of hotwater because he failed to deal with Google quick enough and didn't see the rise of social networking sites such as MySpace and Facebook.
More here. µ