GROUP HAS 5.1 PCT OF UNICORP AMERICAN <UAC> Two affiliated New York investment firms and an investment advisor told the Securities and Exchange Commission they have acquired 555,057 shares of Unicorp American Corp, or 5.1 pct of the total outstanding. The group, which includes Mutual Shares Corp, said it bought the stake for 5.3 mln dlrs for investment purposes and has no intention of seeking control of Unicorp American.