Founded in 1919 by D. W. Griffith, Charlie Chaplin, Mary Pickford, and Douglas Fairbanks, the studio was premised on allowing actors to control their own interests, rather than being dependent upon commercial studios.

…Pickford, Chaplin, Fairbanks, and Griffith incorporated UA as a joint venture on February 5, 1919. Each held a 25 percent stake in the preferred shares and a 20 percent stake in the common shares of the joint venture, with the remaining 20 percent of common shares held by lawyer and advisor William Gibbs McAdoo. The idea for the venture originated with Fairbanks, Chaplin, Pickford and cowboy star William S. Hart a year earlier. Already Hollywood veterans, the four stars talked of forming their own company to better control their own work.

They were spurred on by established Hollywood producers and distributors who were tightening their control over actor salaries and creative decisions, a process that evolved into the studio system. With the addition of Griffith, planning began, but Hart bowed out before anything was formalized. When he heard about their scheme, Richard A. Rowland, head of Metro Pictures, apparently said, “The inmates are taking over the asylum.”

via wikipedia