The SEC is investigating a California company.

Shearson Lehman Bros. said the Securities and Exchange Commission is investigating possible market manipulation of securities in which Shearson was a market maker. The SEC has obtained a “formal order of investigation” relating to possible manipulation of the securities of Hammer Technologies Inc. and related companies, the brokerage company said. Hammer Technologies is a Larkspur, Calif.-based holding company dealing in sales and rentals of video tapes, recorders, televisions, computer products and related equipment.