United Artists and MGM , who released Rocky III , merged in 1980 .
Rocky III is the first installment in the series to be distributed by MGM/UA rather than United Artists alone , after United Artists ' amalgamation into MGM in 1981.The film 's main theme , `` Eye of the Tiger '' , was written by the group Survivor and became a smash hit single , topping the U.S . Billboard charts and receiving an Academy Award nomination for Best Original Song .
Rocky III