U.S. private equity firms Advent International and Blackstone are planning to buy a majority stake in UK data analytics and insights company Kantar.

The firms are holding discussions with British advertising and public relations company WPP PLC to explore bids for a majority stake its data analytics and insights unit.

The transaction, expected to help WPP decrease debt, may value Kantar at up to 3.5 billion pounds ($4.7 billion).

Annually, Kantar generates approximately $4 billion in revenue.