Facebook today announced that its Facebook Exchange platform is coming out of beta today with 15 partners authorized to buy ad inventory through real-time bidding.

A number of beta partners are reporting lower costs per acquisition than on other exchanges and expressed continued interest in FBX, which allows third-party platforms to place retargeting ads on Facebook after users visit external websites marked with cookies. Here are some key stats from companies that shared results:

• 10-20x return on investment, according to TellApart
• 300 percent better cost-per-leads, according to Bizo
• Reduced CPAs by as much as 25 percent, according to AppNexus
• One-fifth the CPA and four times the ROI compared to traditional campaigns, according to Triggit, which also shared the infographic below

Recently added to the list of demand-side platforms approved for FBX is Kenshoo. Kenshoo joins Nanigans and Optimal as existing Ads API partners also authorized for FBX. However, in its current state, advertisers cannot combine Facebook’s demographic- and interest-based targeting with their own cookie data. This limits the potential for creative optimization, though many advertisers expect Facebook to allow this at some point in the future.

For now, the exchange works as so: when a user visits a site that has hired one of Facebook’s partner platforms (DSPs), a cookie will be placed on that user’s browser when the person reaches a stage that implies purchase intent. If a user does not complete a transaction, the DSP will be able to bid on retargeting ads that appear on Facebook when the user visits the social network.

Facebook is hiring two positions directly related to FBX: a partner manager and a technical account manager, suggesting that the company is expecting to bring more DSPs into the program.

Image credit: TellApart