Leading US advertisers are proposing a shakeup of the venerable 'upfront' television airtime buying ritual.

Led by Wal-Mart Stores' svp of marketing communications Julie Roehm, the group is seeking a $50 million (€39.1m; £26.7m) fighting fund to set up a trial online auction system to buy and sell TV advertising.

The group, which also includes Hewlett-Packard, Masterfoods and Microsoft, is interested in testing an idea outlined by leading internet auctioneer eBay at this week's Association of National Advertisers' financial management conference.

The 'Media Marketplace' home web page would allow an advertiser or agency to click on a desired network, age, gender and time; see the available inventory; see the time remaining in the auction; and then enter a bid.

The trading system would be owned and controlled by the ad market. EBay would take a small slice of transactions as a fee and media owners would decide how much of their inventory to offer on the system.

The idea has been touted by Roehm for several years. She says: "We can be the driver of change to bring more transparency and efficiency to media buying."

She believes eBay's solution is "really good" but emphasizes the ad group's steering committee would decide on the technology provider.

Roehm envisages up to 200 advertisers putting in small amounts towards the $50m test costs, although her own company has not committed financially.

Steve Grubbs, ceo of Omnicom Group's media buyer PHD North America, says the system could be used for a variety of media beyond TV.

But he acknowledges that marketers have mixed opinions and that major advertisers such as Procter & Gamble and Pfizer are "already paying bottom dollar" by using their clout in the existing system.

He also notes that the TV networks are unlikely to be impressed: "I don't think they're really going to endorse this. [It] will look at this as a loss of control."

Data sourced from AdAge.com; additional content by WARC staff