The exact size of the stake has not been disclosed, but people close to Interpublic say it owns slightly less than a half percent of Facebook, the newspaper said in its electronic edition.

Interpublic paid less than $5 million for the stake in 2006, the newspaper said.

Interpublic’s stake of 0.4 percent would be worth $200 million, based on a Facebook valuation of about $50 billion, the newspaper said.

Interpublic could not be immediately reached for comment.