Arnold has made a commitment to buy Yahoo! media and promotional programmes on behalf of its clients, which include McDonald's, Volkswagen and Chevron.
The agreement includes media, broadcast services, special promotions and research services.
Wenda Harris Millard, chief advertising sales officer at Yahoo!, said: "Arnold MPG's upfront commitment to Yahoo! to develop marketing programmes for their clients is a groundbreaking development in the online marketing industry. This type of commitment is necessary to support the continued growth and maturity of this marketplace."
Arnold MPG is part of Havas's Media Planning Group network. MPG USA has £2.3bn in billings.
John Gaffney, president of Arnold MPG, said: "Entering a partnership that is the first of its kind in the interactive media industry is an exciting endeavour and working with an established partner like Yahoo! is valuable to our agency and our clients."
Yahoo! has a new business strategy that will see it move away from its reliance on advertising as its revenue source. Yahoo! chief executive Terry Semel plans for 50% of revenues to come from non-advertising sources by 2004, down from the current 76%.
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