Three days after awarding a team of agencies owned by the WPP Group its creative and media assignments, Wachovia suspended the decision when word came out it was being purchased by Citigroup.

The world’s second-biggest advertising and marketing company plans to move because of punitive changes to the British tax regime.

The British market research company Taylor Nelson Sofres rejected again a hostile bid from the WPP Group, but analysts said the company would have difficulty evading WPP.

Because there are usually lower fees, buying off exchanges tends to be cheaper — though more labor-intensive — than buying through networks.

WPP Group, the advertising and marketing company, said it had made a hostile bid for the British market research company Taylor Nelson Sofres.

Ad executives are expressing a growing fear that Web powerhouses like Google and Microsoft want to extend their reach into traditional advertising.