Fannie Mae, the biggest American mortgage buyer, said it won’t file the required first-quarter financial report with the Securities and Exchange Commission on time as it undergoes a restatement of earnings.

The government-chartered company announced the delay yesterday in a filing that also disclosed a decline in the Washington-based company’s share of the market for mortgage-backed securities.

It also missed its third and fourth quarter filings.

The company reiterated that it may need to reduce earnings by $8.4 billion from 2001 to mid-2004 as it corrects its accounting for hedges to its $905 billion portfolio.

The company’s federal regulator in September found it broke those accounting rules and improperly deferred expenses to meet an earnings target that triggered the maximum executive bonuses.

Continued examinations, system upgrades, and other costs related to the restatement boosted administrative costs in the quarter to $440 million from about $383 million a year earlier, Fannie Mae said.

Shares of Fannie Mae have declined 27% since the regulator made public its findings in mid-September and as the violations fueled a movement in Congress to increase regulation of the company and McLean, Va.-based Freddie Mac.

The two companies were chartered by Congress to encourage lending for home mortgages by acquiring loans from banks with the proceeds from bond sales. They make money on the margin between mortgages they own in their portfolios and costs of borrowing in the bond market, and on fees charged to banks for guaranteeing credit on mortgage bonds. They own or guarantee almost half the $7.6 trillion mortgage market.