Prominent Harvard donor A. Alfred Taubman resigned from his position as chair of Sothebys auction house on Monday amidst a U.S. Justice Department investigation into possible antitrust violations at the world-renowned auction house.

Taubman, a Michigan entrepreneur, donated $15 million in 1988 to the Kennedy School of Government (KSG) to build and endow the Taubman Center for State and Local Goverment, where he now serves as chair of the advisory board.

The government is investigating allegations of collusion between Sotheby's and Christie's, a rival auction house, starting in 1997. Three weeks ago, Christie's agreed to cooperate with the government probe and was granted immunity from potential prosecution.

Together, Sothebys and Christie's control about 95 percent of the $4 billion worldwide auction industry.

The investigation has focused on two instances, in 1992 and 1995, in which one firm closely followed the other in changing commission fees.

Sothebys announced its management shake-up on Monday, when both Taubman and President and Chief Executive Officer Diana D. Brooks resigned.

"I have determined that it is time for me to step down from my role as chairman," said Taubman on Monday, in a Sothebys news release. The company declined further comment.

Taubman bought Sothebys in 1983 and took the company public. It now trades on both the New York Stock Exchange and the London Stock Exchange.