March 31 (Reuters) - Tanker operator International Seaways Inc said on Wednesday it will buy Diamond S Shipping Inc for about $416 million, as it aims to expand its crude shipping capacity and create one of the largest U.S.-listed tanker companies. Diamond S shareholders will receive $10.17 per share, or 0.55375 shares, of International Seaways’ stock for each share of Diamond S common stock held, representing a premium of about 5.9% to Tuesday close. International Seaways, which will become the second largest U.S.-listed tanker company by vessel count after the deal, will also assume Diamond S’ net debt of about $5652 million. The all-stock transaction with an enterprise value of about $2 billion is also expected to help save in excess of $23 million in costs annually. The deal, set to close by the third quarter, will also add to International Seaways’ earnings and cash flow per share immediately, the companies said. Shares of Diamond S rose 4.2% in premarket trade. (Reporting by Rithika Krishna in Bengaluru; Editing by Rashmi Aich)