The BBC reports
Yahoo's board has approved a deal to buy New York-based blogging service Tumblr for $1.1bn (£725m), US media reports say.
The acquisition is expected to be announced as early as Monday.
The deal was a "foregone conclusion" and was a unanimous vote by the board, tech blog AllThingsD reported, citing sources close to the matter.
If confirmed, it will be CEO Marissa Mayer's largest deal since taking the helm of Yahoo in July 2012.
Analysts say that by acquiring Tumblr, Yahoo would gain a larger social media presence and enhance its ability to attract younger audiences. It will also help Tumblr generate more revenue from advertisements.
On its home page, Tumblr says it hosts 108 million blogs, with 50.7 billion posts between them.
Under the terms of the acquisition, Tumblr would continue to operate as an independent business, the Wall Street Journal said, citing unnamed sources familiar with the situation.
About 700 million web surfers visit Yahoo's website every month, ranking it among the top in the global industry.