By the end of this weekend, Tumblr founder David Karp will most likely be $250 million richer and Yahoo founder Marissa Mayer will be able to say she outmaneuvered her old friends at Google, not to mention Facebook, Twitter and Microsoft.

Yahoo may be on the verge of closing its biggest acquisition during the 10-month reign of CEO Marissa Mayer as she tries to attract more traffic and advertisers to the Internet company's website and mobile applications.

Updated May 17, 8:20 p.m. EST: Yahoo!’s board plans to meet Sunday to decide whether to approve a $1.1 billion all-cash offer for New York-based social blogging platform Tumblr, AllThingsD’s Kara Swisher and Peter Kafka reported late Friday. If approved by Yahoo!’s board, the deal — which could still fall through — will be announced Monday. Earlier Friday, Yahoo! invited reporters to a “product” ...

Updated May 17, 8:20 p.m. EST: Yahoo!’s board plans to meet Sunday to decide whether to approve a $1.1 billion all-cash offer for New York-based social blogging platform Tumblr, AllThingsD’s Kara Swisher and Peter Kafka reported late Friday. If approved by Yahoo!’s board, the deal — which could still fall through — will be announced Monday. Earlier Friday, Yahoo! invited reporters to a “product” ...

Updated May 17, 8:20 p.m. EST: Yahoo!’s board plans to meet Sunday to decide whether to approve a $1.1 billion all-cash offer for New York-based social blogging platform Tumblr, AllThingsD’s Kara Swisher and Peter Kafka reported late Friday. If approved by Yahoo!’s board, the deal — which could still fall through — will be announced Monday. Earlier Friday, Yahoo! invited reporters to a “product” ...