The World: Los Angeles - Advertisers test online airtime marketplace

Nine of the world's largest advertisers have joined forces to create and test an online marketplace for buying advertising time.

Due to begin in January 2007, the site, which will be designed by eBay and called the Media Exchange, will sell national airtime on a yet-to-be-determined cable channel.

If the test is successful and fully implemented, it could lead to advertisers being able to drive down the average prices for TV advertising space.

The advertisers signed up to participate include Wal-Mart Stores, Microsoft, Home Depot, Lexus, Intel, Philips and HP. They commanded a combined TV adspend of $1.2 billion in 2005.