The court, in a 6-3 vote, threw out an appeals court ruling that would have allowed a retrial of F. Scott Yeager, a former executive at Enron's failed broadband venture, on charges for which a jury could not reach a verdict at his first trial.

But Justice John Paul Stevens, writing for the majority, did not completely shut the door to another trial.

Yeager sold Enron stock for more than $54 million before the company began a downward spiral that ended in bankruptcy in 2001.

In his first trial in 2005, Yeager faced 125 counts and was acquitted of five, including four counts of wire fraud and one of conspiracy to commit wire and securities fraud. The jury couldn't reach a verdict on the remaining counts, which alleged insider trading and money laundering.

Yeager was later reindicted on 13 counts of insider trading and money laundering.

The issue for the court is whether a variation on the Constitution's guarantee against double jeopardy applies in this situation: The jury votes not guilty on some charges, but fails to reach a verdict on others that are based upon the same essential facts as the charges that resulted in acquittal.

Prosecutors frequently retry defendants when juries can't reach a verdict. They cannot pursue a defendant when juries return not guilty verdicts. This case was about what happens when there is a combination of those elements.

Citigroup expects to convert into common stock a total of $58 billion of preferred stock and trust preferred securities, assuming full participation in the swaps.

Citigroup said in late February that it wanted to offer investors the option of exchanging preferred stock into common stock as a way to boost its capital reserves. As such, the government agreed to convert about $25 billion of its $45 billion preferred investment in the bank to common stock, which will give it a 34 percent stake in the New York bank.

The deal boosts Citi's common equity -- a benchmark the government is using to measure a bank's ability to absorb losses.

Citigroup has been one of the most troubled banks throughout the financial crisis. Investors have long criticized its board and management for allowing the bank to make big investments in the risky housing market -- actions that led to Citigroup reporting billions in losses.

Federal prosecutors and the FBI have been investigating possible illegal insider trading by two Securities and Exchange Commission enforcement attorneys who were in a position to receive sensitive information about agency probes of public companies.

The SEC's inspector general, David Kotz, found that the frequent stock trades over a two-year period by the pair raised suspicions of insider trading. Earlier this year, he referred the matter to the Fraud and Public Corruption Section of the U.S. attorney's office in Washington.

That office, together with the FBI, "is conducting an investigation of possible criminal and civil violations," Kotz told SEC Chairman Mary Schapiro in a memo dated March 3.

The memo and Kotz's report of his investigation were provided by the office of Sen. Charles Grassley, R-Iowa, who has been an active critic of the SEC's operations.

Kotz's report also found that the SEC "has essentially no compliance system in place to ensure that ... employees, with the tremendous amount of nonpublic information they have at their disposal, do not engage in insider trading themselves." The agency's disclosure and compliance requirements is based on the honor system and there is no way to determine whether an employee fails to report a transaction.

Four group vice presidents and two vice chairmen sold nearly 205,000 shares Friday and Monday at prices ranging from $1.45 to $1.61 per share. GM shares closed Monday down 17 cents at $1.44.

Spokeswoman Julie Gibson says the sales don't show a lack of faith in the company. She says GM has disclosed publicly that shareholders run the risk of significant dilution or possibly losing their investments in a potential bankruptcy filing.

"They're not operating with any knowledge that other people don't have," she said. The executives had a short window of Friday through Tuesday to sell the shares, she added.

GM has offered bondholders 10 percent of the company's equity in exchange for wiping out $27 billion in debt. The company also is negotiating with the U.S. government for a potential 50 percent share of GM stock, and with the UAW to take 39 percent in exchange for half of the $20 billion that the company owes the trust fund.

The remaining 1 percent would go to those who hold the company's current 611 million outstanding shares.

If the bond exchange goes through, GM plans to issue 62 billion new shares and then do a 100-for-1 reverse stock split.

Charlotte, N.C.-based Bank of America is looking at a shortfall in the billions of dollars, the paper said, citing people familiar with the situation. Both banks plan to rebut the preliminary findings, according to the paper, with Bank of America expected to respond Tuesday ahead of its shareholder meeting Wednesday. Bank of America declined to comment.

Citigroup said in a statement, "Until the results of the stress tests are announced, our regulators have prohibited all financial institutions, including Citi, from making any comments related to the stress tests."

A Citi spokesman added that the bank is continuing with its plan to exchange debt for equity and shed assets as part of a program to further bolster its capital position.

Citi has reached a basic agreement to sell its Japanese brokerage unit, Nikko Cordial, to Sumitomo Mitsui Financial Group Inc. for 500 billion yen ($5.2 billion), according to The Nikkei business newspaper. Citi declined to comment on the potential sale of the unit.

Shares of Citigroup fell 18 cents, or 5.9 percent, to $2.89 in morning trading. Bank of America shares declined 59 cents, or 6.6 percent, to $8.33.

Treasury Department spokesman Andrew Williams said Treasury officials would not comment on whether regulators told Bank of America and Citigroup they may need to raise more capital.