Todd Shipyards will buy back some of its stock.

The New York-based shipbuilding company, which has shipyards in San Pedro, Seattle and San Francisco, said it would buy up to 200,000 shares of its common stock. It said it believes the stock is undervalued and therefore an attractive investment, but it said it has not decided what it will do with the shares that it buys. The company’s stock closed Tuesday at $30.50, up 25 cents. Todd, which this month lost a key Navy contract to build the lead ship of a new destroyer class, has about 4.3 million common shares outstanding.