(Adds background, details on fixed income and investment banking results)
Sept 19 (Reuters) - U.S. investment bank Jefferies Group LLC's third-quarter profit more than doubled from a year ago, as it earned more from advising on debt and equity financing as well as mergers and acquisitions.
Jefferies said on Tuesday net income attributable to the company rose to $83.8 million in the quarter ended Aug. 31, compared with $41.2 million, a year earlier.
Revenue from investment banking, which includes underwriting and advisory services, soared 61 percent to $475.7 million.
In the quarter, Jefferies provided debt financing to Sycamore Partners' $6.9 billion deal to buy Staples Inc . U.S. oil and gas company Penn Virginia Corp also hired Jefferies as it explored a possible sale.
New York-based Jefferies, a unit of Leucadia National Corp , traditionally kicks off the earnings reporting season for investment banks. Its results are viewed as an indicator of big Wall Street banks' performance.
Jefferies said total equities and fixed income revenue fell about 7 percent to $319.5 million, hurt by subdued trading volumes and volatility during much of the quarter.
JPMorgan Chase & Co, Bank of America Corp and Goldman Sachs have already warned that trading conditions during the third quarter will likely be poor as bonds and stocks continue to suffer from decreased market activity and volatility.
JPMorgan expects a 20 percent slide in trading revenue, while BofA and Citi expect a nearly 15 percent fall.
Jefferies said its net revenue jumped 22.3 percent to $800.7 million. (Reporting by Nikhil Subba in Bengaluru; Editing by Sai Sachin Ravikumar)