Following rumours at the tail-end of last week, Yahoo is expected to confirm that it has bought Tumblr for $1.1 billion.

According to sources talking to All Things D - the tech blog for The Wall Street Journal -  the Yahoo board met on Sunday to vote unanimously in favour of buying the blogging platform.

Fuelling the speculation, Yahoo has announced that it will be holding a press conference in New York on Monday, when it is expected to deliver the news.

Tumblr was started in 2007 by David Karp, a 26-year-old New Yorker. The report says he is expected to remain in his role for at least four years.

It is expected that Tumblr will be left to its own devices to run as a solo company, much like Instagram and Facebook, but will however benefit and leverage Yahoo's huge advertising infrastructure.

The deal, the biggest since Marissa Mayer became Yahoo CEO, follows a series of smaller deals as the company tries to turn itself around.