Shares of Fannie Mae fell nearly 11 percent yesterday following a news report that investigators looking into the mortgage company's finances have unearthed further accounting violations.

The report by Dow Jones Newswires, citing anonymous sources "close to" or who "have been involved" in the investigation, said that the company overvalued its assets, underreported credit losses, and misused tax credits.

Fannie Mae officials declined to comment on the allegations, as did the company's chief regulator, the Office of Federal Housing Enterprise Oversight, which first uncovered accounting violations at Fannie Mae last year. OFHEO, in a preliminary report of its findings, had said that the company did not properly account for losses on derivatives, financial instruments that Fannie Mae relies on to protect the value of its assets from swings in interest rates.

In December 2004, the Securities and Exchange Commission ordered Fannie Mae to restate roughly $10.8 billion in previously reported earnings, leading to the ouster of chief executive Franklin D. Raines and chief financial officer J. Timothy Howard.

The accounting scandal has prompted a move in Congress to more strictly regulate the mortgage finance company, which buys mortgages from banks and other lenders and packages them into securities for sale to investors.

OFHEO, which is still investigating Fannie Mae's finances, is expected to issue its final report by March 31, an agency spokeswoman said.

The Securities and Exchange Commission and federal prosecutors also are investigating Fannie Mae, in addition to a probe ordered by the company's board and led by former senator Warren B. Rudman. Rudman has said he expects to release his findings by the end of the year.

Wall Street analysts found the Dow Jones report less alarming than did the markets. "As we've been saying for quite a while, we do think the accounting problems and operational problems are going to be significantly more dramatic than most have expected," said Josh Rosner of Medley Global Advisors LLC in New York.

In a separate announcement, OFHEO said that as of June 30, Fannie Mae had sufficient capital on hand to meet regulatory requirements, and anticipated the company will come up with an additional $5.9 billion that OFHEO has mandated it put aside as a result of the accounting violations.

Fannie Mae stock closed at $41.71, down $4.99.