Time Warner's AOL has purchased an online affiliate marketing network named Buy.at in order to bolster its ad infrastructure, MediaPost reported. Financial terms of the deal were not disclosed.

Since 2007, AOL's acquisitions have mostly focused on ad serving to build its overarching Platform-A advertising unit, while Buy.at is expected to give AOL a more direct relationship to online retailers.

Buy.at is a network where advertisers can pay its member Web publishers based on user actions. The network also has an e-commerce platform where merchants can sell their products through third-party sites.

According to MediaPost, the purchase comes just several days after Microsoft's offer to buy Yahoo, which has aroused acquisition rumors for AOL. It also came a day prior to Time Warner's 1Q financial report, which is expected to include guidance on the future of AOL.

Targeting the largest marketers and ad agencies, AOL set up Platform-A last year to encompass its various ad networks. Platform-A works closely with Advertising.com, the AOL unit that matches online ad buyers to thousands of sites with extra ad space to sell.

"This acquisition further enhances Platform-A advertising offerings by enabling us to offer a new set of advertiser and publisher products, while also supporting our international strategy," said AOL Chairman and CEO Randy Falco in a statement, according to MediaPost.