M&A report surfaced on financial blog.
Briton plans to stay involved in marketing and communications world.
The Vivendi-owned agency group made the disclosure in its stock market prospectus.
The change impacts APAC markets, including Singapore, New Delhi, Jakarta, Hong Kong, and Sydney, while R3 China will continue to operate as a MediaSense affiliate.
Bosses could get extra $8 million in cash bonuses for working on separation from Vivendi, prospectus reveals.
The agency group cut revenue forecast in August but won Amazon and retained Unilever in key markets.
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