New York investor Ivan F. Boesky has acquired an 8.7 percent interest in SCM Corp., the target of a bidding war between Hanson Trust PLC and Merrill Lynch, a Securities and Exchange Commission filing revealed yesterday.

Hanson Trust Tuesday sweetened its offer for SCM to $72 a share in cash, eclipsing a $70-a-share joint bid by Merrill Lynch and SCM executives to take the diversified typewriter manufacturer private in a leveraged buyout. SCM told securities regulatory officials yesterday that its agreement with Merrill Lynch would be terminated unless the offer is raised to at least $72 a share within five days. Hanson Trust said it is prepared to proceed with its cash tender offer for SCM shares now that the Federal Trade Commission has granted its request for early termination of the waiting period required under federal antitrust law.

In an SEC filing, Boesky and a group of companies he controls said they had bought 864,900 shares of SCM between Aug. 22 and Aug. 29 at prices ranging from $63.375 to $68.125 a share.

SCM stock, which jumped $5 to $72 a share on the New York Stock Exchange Tuesday, was unchanged yesterday at $72. The Boesky group said in the filing that it bought the SCM shares "in connection with merger arbitrage and other investment activities."