AOL has introduced a new web marketplace where clients can bid on unsold advertising space on the thousands of websites served by Platform A.

The new system allows prospective buyers to bid on ads using traditional pricing, based on how many see the promotion, or based on how many people click an advertisement. Previously, buyers worked with separate sales representatives for each of AOL's acquired companies, including Tacoda and Advertising.com.

The sites served by Platform A reach 90 percent of U.S. internet users, according to comScore.