“ On October 20, 1955, a consent decree was entered by the District Court for the Southern District of New York, the terms of which provide that the managing companies must make their artists available to all concert services at the same rate and that the concert services must make performers available to audience associations without reference to the management of the artists. ”

“ Columbia's standard contract with concert services contains a provision, which Columiba argues is required by a collective bargaining agreement among managers and the concert artists' union, prohibiting a concert service from booking an engagement at less than the artist's established fee without the consent of the artist. ”

“ Normally an audience association pays an artist an established fee set by the artist and his manager, out of which the artist's manager retains a share and the concert service also retains a share known as the 'margin.' The Government's complaint charged a conspiracy to monopolize the business of managing and booking concert artists and the business of forming and maintaining audience associations. ”