Yahoo has agreed to acquire popular blogging service Tumblr for $1.1 billion, according to media reports on Monday.

If confirmed, the acquisition will be CEO Marissa Mayer's largest deal since she took the helm of Yahoo in July 2012.

The acquisition, slightly more than Facebook鈥檚 acquisition of Instagram for $1 billion last spring, could be officially announced as soon as Monday at a news conference Yahoo has scheduled in New York City where Tumblr is based.

Yahoo has been striving to purchase young startups in order to regain the company's relevancy in an Internet environment now dominated by Google, Facebook and Twitter.

Yahoo has "wanted something that has Facebook and Twitter like features for many years," said Ross Rubin, founder and principal analyst at Reticle Research of New York.

"This would allow it to have a way to build a community again, to create an alternative to Facebook and Twitter that doesn't need to start from scratch the way Google+ is trying to do," Rubin said.

Tumblr is currently run by David Karp, a 26-year-old New Yorker who founded Tumblr in 2007, and he is expected to remain in his role.