The INTERNATIONAL MANAGEMENT GROUP (IMG), credited with being pioneers in the development of modern sports agentry, began in 1960 when Cleveland lawyer and amateur golfer Mark H. McCormack represented professional golfer Arnold Palmer as his agent in business and promotional affairs. With McCormack as his agent, Palmer saw his income increase from $59,000 in 1959 to nearly $500,000 in 1962, and was one of the first athletes to appear in a television commercial. McCormack then acquired golfers Gary Player and Jack Nicklaus as clients, and by 1967 he had left the law firm of ARTER & HADDEN to operate his sports-promotion agency at One Erieview Plaza.
In the next two decades, the number of IMG's clients, its revenues, and its range of activities grew dramatically as it created and produced sports events for television and operated as business agent for both the Wimbledon tennis tournament and the London Symphony Orchestra. IMG brought the World Series of Women's Golf tournament and the World's Championship of Women's Golf to Cleveland in 1980 and 1981, respectively. Annual revenue as of 1986 exceeded $300 million. By 1995 the firm was promoting athletes and sporting events for more than 1,000 clients. It charged 25% of an athlete's income to take care of his or her finances, make investments, secure endorsements, pay bills, and prepare taxes. Once considered the dominant force in the management and promotion of tennis and golf athletes and tournaments, IMG greatly expanded and diversified its representative scope by the 1990s to include not only sports-related clients, but performing artists, writers, fashion models, broadcasters, leading corporations, cultural institutions and recreational resorts. In 2002 IMG had 3,000 employees in 85 offices in 33 countries. Mark H. McCormack died on 16 May 2003 at the age of 72. Co-CEOs Bob Kain and Alastair Johnston were appointed to head IMG.