Moody's U.S. debt downgrade is raising concerns that investors could reevaluate their appetite for U.S. government bonds, with the potential for rising yields to put pressure on stocks that are trading at elevated valuations.

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%.

Investors will get the first chance to react to Moody’s downgrade of the U.S. credit rating late Friday over rising government debt and they’ll also look for more progress from President Trump on trade deals as the week kicks off.