Mark Penn’s Stagwell Group has agreed to acquire National Research Group from Nielsen for an undisclosed price.

The firm, which has over 100 employees and offices in Los Angeles and London, provides Hollywood studios with tracking data in the weeks leading up to the release of their movies.

Penn, managing partner and president of Stagwell Group, is a former political strategist and pollster. He was a key advisor to Bill Gates and Microsoft Corp. in the ’90s. He formed the private equity group that carries his name last year.

Stagwell noted the deal for NRG represents its second acquisition in the marketing services industry this year, following its purchase of strategic communications specialist SKDKnickerbocker LLC.

NRG was founded by Catherine Paura and the late Joseph Farrell in 1978. They sold the firm in 2003.

NRG conducts over one million tracking survey interviews annually online and by mobile phones across the 13 largest movie markets around the world. It also conducts research through movie screenings, focus groups, exit surveys, ad/trailer testing and studies.

“We are excited to welcome NRG into the Stagwell family of companies and as a market research practitioner for the last 40 years I’m particularly pleased to add these key capabilities,” said Penn. “NRG has been a global leader in Hollywood market research and we see product innovation as a key ingredient for success in a rapidly changing entertainment marketing landscape.”

Howard Ballon has been appointed interim CEO of NRG upon closing of the transaction.

Stagwell Group was formed last December by Penn. The fund previously announced it has raised $250 million in capital and may use that to make up to $750 million in acquisitions.

Penn was the CEO of the PR firm Burson-Marsteller until 2012 and president of the polling firm Penn, Schoen and Berland Associates.