The deal is another sign of CEO Sir Martin Sorrell's strategy to diversify WPP's holdings beyond pure advertising and into broader marketing services. Sir Martin has said that these areas are more profitable than traditional advertising. In recent months, WPP has acquired a number of other public relations and marketing firms.
WPP shares continued to rise this morning, jumping a further 11p on yesterday's close of 663.5p.
Yesterday, WPP saw its shares finish 18.5p up on the day, following comments by AOL Time Warner CEO Gerald Levin that advertising revenues have stopped falling.
Levin was speaking at the Cannes International Advertising Festival, where he told reporters that he does not believe there is an upturn yet, but stressed that advertising revenues are stabilising.
WPP was up almost 3% yesterday while its rivals experienced much smaller rises. The Interpublic Group of Companies rose just 0.2% to $28.30 (£20) and Omnicom Group rose a little more, up 0.3% at $82.20 (£58.12).
Back in the UK, Cordiant Communications was also up, but again only fractionally at 0.5% to 201p. There was no change at Tempus at 418.5p and the CIA-owning Aegis Group was down 0.7% at 114.2p.
However, analysts were sceptical that the move signalled a recovery and warned that one comment was not enough to signal a recovery.
WPP said in a statement that its latest acquisition, the Kansas City-based VML, had revenues of $18m (£12.7m) in the year to November 30. VML's clients include the Coca-Cola Company and American Express.