• by Gavin O'Malley  @mp_gavin, May 18, 2011

Hoping to build new publisher partnerships, Yahoo on Wednesday announced an agreement to buy ad platform 5to1. Financial terms of the deal were not disclosed, but unconfirmed reports put the price in the $25 million-to-$30 million range.

"5to1 provides additional access to publishers and unlocks the value of unsold inventory for premium brand advertisers," according to Wayne Powers, Yahoo's senior vice president, advertising sales for the North America region.

5to1 says it now works with more than 20 top publishers, although it has not named them.

Expected to close by the second quarter of the year, the 5to1 team will join Yahoo as part of its Ad Marketplaces group.

Likely facilitating the sale of the company was 5to1 co-founder Ross Levinsohn, Yahoo's current executive vice president, Americas, and formerly the president of Fox Interactive Media.

Along with Levinsohn, Jim Heckman and Michael Barrett -- also former Fox Interactive Media execs -- launched 5to1 in late 2009.

The idea was to help publishers remove unwanted ads from their sites by offering them a system to "shop" for ads from an iTunes-like online store. Likewise, the company was positioned as an antidote to remnant ad networks, which offer ads that arguably detract from the value of the content they surround.

The name 5to1 came for the Doors song "5 to 1," whose lyrics incite rebellion: "They got the guns, but we got the numbers. Gonna win, yeah, we're taking over."

Also of note, 5to1 CEO James Heckman sold another company he founded, Rivals.com, to Yahoo for a reported $100 million in mid-2007.

To date, 5to1 has raised $12.8 million led by Fuse Capital, where Levinsohn spent nearly three years as managing director before joining Yahoo late last year.