• by Laurie Sullivan  @lauriesullivan, October 21, 2013

Google will soon work with Facebook through an agreement that allows advertisers using Google's DoubleClick ad-buying platform to buy retargeted ads on Facebook. Starting in a few months, advertisers will have access to buy inventory on FBX via DoubleClick Bid Manager.

DoubleClick allows brands to buy ads on a variety of ad exchanges, excluding Facebook until now. FBX launched in June 2012, allowing advertisers to buy cookie-based retargeted ads on Facebook's site. In the past year, since the launch of the exchange, the platform has become a driving force in the ad-serving industry, as the company drew on partnerships with demand-side platforms (DSPs) for strength.

AdRoll, AppNexus, DataXu, MediaMath, TellApart, Triggit and Turn were among the original DSPs to support FBX. Google DoubleClick Bid Manager, which the company acquired in 2010, will support the agreement similar to the way most DSPs do, through browser cookie data. Bid Manager allows marketers to buy online ad space at Web sites across the Internet.

Marketers may wonder whether opening Facebook's exchange to Google bidding will increase prices, given higher competition. Brands that are reliant on DoubleClick Ad Manager want easy access to FBX inventory. Facebook also needs the ad dollars for revenue growth, especially now that it's a public company. The partnership could mean higher revenue for both companies.

Separately, rumors have begun to surface that Amazon would also gain access to FBX, closing the loop on some very large Web properties and creating a network for ad-serving across a major online retailer, search engine and social media network.

comScore has released its top 50 properties list for September 2013. On the desktop, Google sites ranks No. 2 with 191,448 unique visitors, followed by Facebook at No. 4 with 142,248 unique visitors and Amazon sites at No. 6 with 110,863 unique visitors.