All things being equal, people will do business with a friend; all things being unequal, people will still do business with a friend.

They married in 1986. In 1960 McCormack signed golfer Arnold Palmer as IMG's first client and later signed Jack Nicklaus and Gary Player. He also handled special projects for Margaret Thatcher Mikhail Gorbachev Pope John Paul II and Tiger Woods.

Mark Hume McCormack (November 6 1930 – May 16 2003) was an American lawyer sports agent and writer. He was the founder and chairman of International Management Group now IMG an international management organization serving sports figures and celebrities. The 2004 romantic comedy Wimbledon starring Kirsten Dunst and Paul Bettany was dedicated to McCormack's memory in recognition of all that he contributed to both tennis and golf.