NEW YORK (Reuters) - Lehman Brothers LEH.N is in talks for potential sale of its $40 billion (21 billion pounds) portfolio of commercial real estate and securities in an effort to bolster its finances following costly credit-related write-downs, the Financial Times said in its online edition.

The investment bank wants to sell the assets either as a whole or in pieces, the FT said, citing people who have been involved in the discussions between Lehman and potential buyers.

Lehman has offered to shoulder the first $5 billion of any losses suffered on the portfolio's assets following a sale, the sources said.

The portfolio includes mortgages and mortgage-backed securities that were valued at $29.4 billion as of May 31, the article said. It also contains real estate assets worth $10.4 billion at the end of May, according to the report.

Lehman officials could not immediately be reached for comment.

(Reporting by Ransdell Pierson; editing by Carol Bishopric)