LONDON (Bloomberg) - Overseas Shipholding Group Inc., a US oil shipper, climbed in New York trading on Friday after Bermuda-based shareholder Frontline Ltd., the world's largest owner of supertankers, said it may seek to buy the company. Overseas Shipping shares have advanced about nine percent this year, compared with 26 percent from Bermuda-based Frontline. Frontline owns a five percent stake and expects to talk to the Overseas Shipholding's managers, board and other investors, Frontline said.