The sale valued Kantar at $4 billion. : WPP has agreed to sell a majority stake of its market research company Kantar to private equity firm Bain Capital. The agency holding company confirmed on Friday that it has reached an agreement to sell 60% of Kantar to Bain as part of chief executive Mark Read's strategy to reduce debt and simplify the structure of the company. The deal values Kantar at $4 billion. Proceeds to WPP on completion after tax and continuing investment in Kantar are expected to be about $3.1 billion, the group said.