Two West Coast investment firms and a private investor reported last week that they had purchased about 37 percent of the stock in Baltimore-based Arundel Corp., a real estate developer and construction materials supplier.

St. Francis Investment Co., a San Fransisco company that provides management and professional services to a group of businesses, trusts and individuals, and Pilara Associates, a small investment management firm based in Lafayette, Calif., bought 260,850 shares of common stock, or 12.9 percent of Arundel's outstanding shares.

St. Francis said it made the purchase for investment purposes only. But Pilara intends "to continue to explore, evaluate and support any moves to improve the return on their client's investment in Arundel by any appropriate means," company official Andy Pilara said. The options include sale of company assets, a change in Arundel management or a merger, Pilara added.

In a separate transaction, Arundel Chairman Henry Knott reported boosting his stake in Arundel to 519,775 shares, or 25.32 percent of the company's shares.

Knott's shares include his personal holdings and three trusts of which he is a trustee. He purchased the 206,353 shares between Oct. 10 and Oct. 30 in open-market and private transactions for prices ranging from $18.50 to $20.35 per share. Knott also purchased 208 preferred shares in a private transaction on Oct. 23.

Arundel, based in Towson, has construction materials subsidiaries in Virginia, North Carolina, Maryland and Delaware. The company also has real estate holdings in Maryland, New York, New Jersey, Virginia and Alabama.