Lehman Brotherslost about $600m on a single hedging position in the second quarter, adding to what is expected to be a larger than anticipated loss that may lead the bank to raise more capital by selling a stake to an outside investor.

People close to the matter said Lehman has opened talks with potential investors including asset managers and Asian banks. Analysts have suggested Lehman could look to raise as much as $4bn in new capital. Lehman declined to comment.