Bill Ackman, a billionaire financier, competed in the Hall of Fame Open in Newport, R.I., on Wednesday. He was the doubles partner for Jack Sock, a retired professional.

Ackman put up $900 million of Pershing Square's cash in exchange for 9 million shares of the stock, giving it a 46.9% economic stake in the company and 40% control of the vote.

After losing his first professional doubles tennis match, billionaire Bill Ackman is facing a range of criticism The match took place in Rhode Island at the Hall of Fame Open on Wednesday, July 9 ...