American stocks rose, sending the Standard & Poor’s 500 Index to a four-month high, as loosened government restrictions on Fannie Mae sparked a rebound in financial shares and oil companies advanced on record crude prices.

Fannie Mae gained, helping financials erase a 1.9% decline, on a regulatory decision that will enable the biggest mortgage-finance company to buy more home loans. Anadarko Petroleum Corp. climbed to a record after profit exceeded estimates and crude topped $122 a barrel. Advanced Micro Devices Inc. rallied the most since January on speculation the second-biggest maker of computer processors may be split up.

“It continues the trend where people are speculating the worst is over in terms of the financial sector,” a portfolio manager at Security Global Investors in Irvington, N.Y., which manages $11 billion, Mark Bronzo, said. In financials yesterday, “the reversal is impressive,” he said.

The S&P 500 erased yesterday’s retreat and pared its 2008 decline to less than 3.4%. The benchmark for American equities has rebounded more than 11% since a 19-month low on March 10 after first-quarter earnings topped estimates at 69% of companies that have reported results so far, according to data compiled by Bloomberg.

Fannie Mae climbed 8.9% to $30.81 after dropping as much as 7.3%. Regulators said they will loosen restrictions on Fannie Mae’s capital once the company has raised $6 billion in new funding. Fannie Mae, which owns or guarantees one of every five American home loans, needs fresh capital to weather credit and derivative losses that rose fivefold to $8.9 billion.

The money raised will enable Fannie Mae to “emerge from this crisis” in a stronger position, the chief executive officer, Daniel Mudd, said.

Fannie Mae fell earlier after posting a first-quarter loss of $2.19 billion and cutting its dividend. Freddie Mac, Fannie Mae’s smaller competitor, added $1.81 to $27.33.