• by Mark Walsh  @markfwal, September 14, 2011

Demand-side platform Turn has partnered with Nexage to power real- time bidding (RTB) for mobile advertising inventory through its media-buying platform. The pairing will allow Turn's clientele of more than 60 Fortune 200 brands to buy mobile Web and applications on an individual impression basis.

Nexage operates a mobile RTB exchange that provides access to billions of mobile impressions from more than 200 publishers and 700 sites and applications. It counts "Angry Birds" maker Rovio among its clients. By some estimates, about 80% of mobile inventory goes unsold, creating an opportunity for an exchange like Nexage.

The alliance lets Turn expand the scope of inventory it provides. "This enables our clients to integrate the mobile channel with their display and video campaigns and delivers on the promise of multi-channel advertising," stated CEO Bill Demas. The company also works with mobile ad network Jumptap to supply mobile inventory. Turn has raised $58.5 million in venture funding to date from backers including Norwest Venture Partners.

Last month, the company struck a similar deal with Web video ad company TubeMogul, to power real-time buying of mobile video ad space for TubeMogul's PlayTime DSP.

Other DSPs have also extended their offerings to mobile. Earlier this year, DataXu launched its own RTB platform for mobile, dubbed DX Mobile. The various mobile platforms generally promise features including advanced targeting, optimization that automatically allocates ad spending most efficiently, and attribution metrics and analytics.