The WPP chief executive, Sir Martin Sorrell, has criticised the £92m price tag that rival Publicis paid for digital operation Business Interactif, citing it as an example of the "excessive" valuations some media businesses are attracting.
Speaking to MediaGuardian.co.uk, Sir Martin said that while there were "still a lot of opportunities" for acquisitions and consolidation in the media sector - more so in the private market than in the public market - many valuations could be described as being on the "excessive side".
He highlighted "recent activity in France", pointing to long-time rival Maurice Levy's £92m acquisition in June of Business Interactif, which has offices in France, China and Japan.
Publicis aims to merge Business Interactif with its existing digital advertising operation Digitas - acquired for $1.3bn (£657m) last December - to create a global digital agency network.
Sir Martin said he was in agreement with comments made by Vincent Bolloré, the chairman of advertising group Havas, at the Cannes Advertising Festival in June about not getting caught in an "acquisition race" that could see prices of targets pushed to an unsustainable level.
Looking forward, Sir Martin said that WPP had two firm goals in mind. He said that the company must ensure it continued to dominate fast-growing markets such as Asia and also dominate the development of digital services relating to mobile, the internet and video.
He said China was now the third-largest market for WPP - after the US and the UK - accounting for around $600m in revenue, while India accounts for more than $200m.
"We must maintain our position in these markets," he said.
Sir Martin pointed to a report published earlier this week by Group M, WPP's combined media planning and buying operation, that highlighted how China will overtake Europe's two biggest advertising economies, the UK and Germany, within a year and take the US's title as the biggest contributor to the growth of global advertising.
In WPP's interim results today, the company described how the advertising and marketing industry was entering a "third era", involving the application of technology where "high science is being increasingly applied" to the industry.
WPP cites Google's $3.1bn bid for DoubleClick, Microsoft's $6.1bn purchase of aQuantive and its own $650m deal to buy 24/7 Real Media as examples.
Describing the "third era" phenomenon, the company said: "It does not include, as some have suggested, the purchase of digital agencies. This land grab has also set off a related wave of agency consolidations."
WPP also said today that it estimates that Group M, which is made up of WPP-owned media agency networks Mindshare, Mediaedge:cia, Mediacom and Maxus, has planned or bought the media space for one in four of all global advertisements.
Sir Martin was relatively relaxed about any potential knock-on effect that trouble in the US sub-prime mortgage market - which has seen stock markets slide across the globe - might have on WPP's operation.
"I don't think the sub-prime liquidity woes will affect the real world for a year or so," he said. "It is the political cycle that determines our lives, then the economic cycle."
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