Stock exchange traded funds (ETFs) ended a volatile trading day mostly flat on reports of a Greece funding deal, while Moody issues a warning about U.S. Debt.

The S&P 500 rebounded from earlier losses on Thursday following news of a fresh funding plan to help Greece pay off its mountain of debt. A new three-year adjustment plan for Greece was agreed in principle by senior euro-zone officials, according to a source close to the negotiations. The S&P 500 recouped some lost ground on word about the Greece plan after taking out its lowest point for May at 1,311.80, as nervous investors focused on key market levels to manage risk. The slide below May’s low had come a day after stocks’ worst one-day fall in nearly a year. The SPDR S&P 500 ETF (NYSEArca:SPY) ended the day flat.

The dollar slid further to a three-week low against the euro, after a news report said senior euro-zone officials have come to a tentative agreement to extend loans to Greece for three years. The plan would involve some participation of private-sector investors, but it would be limited to avoid triggering a credit event or default, according to the report. The euro strengthened after European Central Bank President Jean-Claude Trichet boosted hopes for a more coordinated fiscal policy to deal with the high debts of euro-zone member countries. The PowerShares DB U.S. Dollar Index Bullish ETF (NYSEArca: UUP) closed slightly lower on Thursday.

Financial stocks were mixed on Thursday, with concerns over a report that Goldman Sachs (NYSE: GS ) has received a subpoena from prosecutors probing the financial crisis. In New York, Goldman’s shares tumbled 2%, before paring losses, on unconfirmed reports it had received a subpoena from the Manhattan District Attorney’s office as part of a probe of the firm’s activities in the run-up to the financial crisis. Other US financial stocks came under pressure after Moody’s said it would review for possible downgrade ratings that include exceptional government support assumptions for Bank of America (NYSE: BAC ), Citigroup (NYSE: C ) and Wells Fargo (NYSE: WFC ), put in place during the financial crisis. The SPDR KBW Bank ETF (NYSEArca: KBE) closed flat today.

A credit rating agency is warning the U.S. government that it could lose its sterling credit rating if Congress and the Obama administration don’t reach an agreement to raise the nation’s borrowing limit. Moody’s Investors Service says if the parties fail to make progress soon, it would put the U.S. rating under review for a possible downgrade. That’s because there’s a “very small but rising risk” that the government will default on its debts. Moody’s warned the government could also face a downgrade if it fails to come up with a plan to control the country’s rising debt. The ProShares UltraShort 20+ Year Treasury ETF (NYSEArca: TBT) surged over 3.5% higher today.

Gregory A. Clay contributed to this article

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