They are now braced for a double whammy, with further consolidation of TV sales houses, including Channel 4 and Five, seemingly inevitable.
Some advertisers predict turmoil in the ad market and are threatening to pull money out of ITV if it exploits its position.
The decision is "a slap in the face for advertisers and a total victory for ITV", according to Jim Marshall, chairman of the Institute of Practitioners in Advertising Media Futures Group, which led agency opposition to a merger.
Bernard Balderston, Procter & Gamble's associated director of media, warned: "ITV may think it has done well out of this, but if it seeks to exploit the situation it will be viewed negatively by the marketplace."
Guy Phillipson, head of advertising for Vodafone UK, added: "ITV is very important for mobile networks, but we will look at other media if we have to."
But advertisers may face similar monopolistic conditions in other TV markets if other channels react by merging their sales houses, as is being predicted.
The Competition Commission has ruled out any divestment of ITV's two sales houses -- a minimum precondition for a merger demanded by advertisers through their representative bodies, the IPA and the Incorporated Society of Broadcast Advertisers. Officially, ISBA gave a cautious welcome to the deal but warned that there was "devil in the detail" of the merger conditions.
Some members of the commission were keen on the divestment option, but it was ruled out as too complicated. Instead, the commission has insisted only an a "behavioural" remedy, which allows advertisers to roll over their 2003 contracts for a period of three years. An adjudicator is to be hired to referee any disputes.
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