NEW YORK--(BUSINESS WIRE)--Fitch Ratings has affirmed the ratings of the Interpublic Group of Companies, Inc. (IPG) including its Issuer Default Rating (IDR) at 'BBB'. The Rating Outlook is Stable. A full list of rating actions follows at the end of this release. KEY RATING DRIVERS --IPG's ratings reflect its position in the industry as one of the largest global advertising and marketing services holding companies, its diverse client base, and the company's ample liquidity. --The ratings incorp