The job cuts would amount to nearly 5 percent of the work force of the fourth-largest U.S. investment bank, which has already announced three other rounds of cuts totaling about 4,000 positions this year.

The precise number of staff laid off is still being determined, the person familiar with the matter said.

Wall Street firms are broadly reeling from the credit crunch, and Lehman is no exception. It is looking for buyers for some $40 billion of commercial mortgages and property on its balance sheet.

Investors fear that write-downs of its commercial and residential mortgage assets could be large enough to dramatically reduce the company's net worth, which stood at about $26.3 billion at the end of May.

Lehman's shares trade at less than half their book value, even as many of its competitors trade at a premium.

Many of Lehman's strongest businesses, ranging from fixed income underwriting to advising on mergers, have been much weaker this year compared with last year.

Given the potentially large write-downs, some of Lehman's critics have charged the company is undercapitalized. The bank has raised roughly $12 billion of capital this year through common equity, preferred stock and convertible securities offerings.

Lehman is looking at raising additional capital by selling a stake in its asset management business, sources have said.

Lehman had about 26,200 employees at the end of May.

(Reporting by Dan Wilchins; Editing by Braden Reddall)