A group of German online publishers have revealed plans to launch a publisher exchange for their premium ad inventory. The new exchange marketplace includes four of the country’s leading online publishers: G+J Electronic Media Sales, IP Germany, Seven One Media and Tomorrow Focus (now the majority shareholder in Adjug).

All four publishers attract a total of sixty-five million unique users to their online properties every month, and generate hundreds of millions in guaranteed ad impressions.

The technology for the new platform will be provided by Wunderloop. Project Mars will use Wunderloop’s audience segmentation, user profiling, booking and inventory forecasting tools to power the new exchange marketplace - offering agencies and advertisers the platform to buy specific audience across all four particpating publishers' ad inventory.

It is understood that Project Mars will run alongside the existing sales operations of member publishers to prevent sales channel conflict.

Project Mars will have a dedicated sales team initially, which will work with agencies and advertisers. The new platform is likely to have an open API for agencies and DSPs to integrate with, allowing traders to buy directly from the marketplace. There has been no word on RTB functionality.

The new platform has already received the green light from the EU, as the commission felt that the new venture would not create imbalance in the online ad market.

This is a fascinating development. It’s not often you see publishers working together like this. Clearly this group of German publishers sees real commercial advantage in running its own exchange. It is probably worth noting here that German publishers prefer not to work with ad networks, and that a publisher exchange is arguably a natural progression to scale the reach so as to attract a greater number of online media buyers.

Is the publisher exchange a trend the industry is likely to see continue? There has been a lot of debate around the advent of automated ad trading and the audience media buy over the past twelve months.

Publishers are now being forced to review how they currently sell their ad inventory. Yield optimisers and ad exchanges have emerged to help publishers trade more effieciently and mximising revenues. But a publisher-owned exchange is a relatively new phenomenon.

There could be a big revenue opportunity here for ad-tech players like Wunderloop or some of the yield optimisers to licence technology to these new publisher-owned exchanges.

Project Mars could of course be a one-off experiment: collaboration is rarely successful in markets like the US and UK; and German publishers do have a history of working well together. But given the continuing decline in online display revenue, more publisher-owned exchanges are likely to appear in the year ahead. It'll be interesting to see in what markets these publisher platforms take hold.