United Talent Agency, which represents stars such as Angelina Jolie and Kevin Hart, sold a minority stake to private equity firms Investcorp and PSP Investments, raising money it will use to acquire companies and bolster one of Hollywood’s largest talent shops. The deal values the company at about $800 million, according to a person familiar with the matter. The funds may be used to acquire companies and deliver cash to partners who have held onto stakes for years, said the person, who asked not to be identified because the transaction is private.