Stocks slumped at the open of trading on Monday after a downgrade of U.S. credit triggered a spike in debt yields that threatened to raise borrowing costs throughout the nation's economy. The Dow Jones Industrial Average dropped 295 points, or 0.7%, while the S &P 500 fell 0.9%. The tech-heavy Nasdaq plunged 1.2%.

All three major U.S. stock market indexes rose Monday afternoon, following an earlier selloff sparked by long-dated Treasury yields surpassing the 5% mark after the financial ratings agency Moody’s downgraded the U.S. government’s credit rating late last week, citing rising debt and interest payment ratios.