The California-based Internet pioneer did not reveal financial terms of the acquisition.
"5to1's innovative platform and premium private marketplace will further enable Yahoo! to extend our advertising leadership," said Wayne Powers, senior vice president of advertising sales for Yahoo! in North America.
"5to1 provides additional access to publishers and unlocks the value of unsold inventory for premium brand advertisers."
US-based 5to1 launched in 2009 as a market for advertisers and website publishers when it comes to unsold supplies of premium ads.
Source: AFP
