Complex sentence: Deutsch is the chairman of Deutsch, Inc., an advertising agency company founded by his father, which he sold to Interpublic Group of Companies (IPG) in 2000 for $265 million.
Split into simpler sentences: Deutsch is the chairman of Deutsch, Inc., an advertising agency company founded by his father that is owned by Interpublic Group of Companies (IPG). In 2000, Donny sold his agency to the Interpublic Group of Companies (IPG) for $265 million.