Investors largely shrugged off a downgrade of the U.S.'s credit rating in Monday trading as stocks ended the day mostly flat.

U.S. stocks finished near the unchanged mark on Monday with market sentiment weakened by the downgrade of the federal government's perfect sovereign credit rating owing to its huge debt profile. Moody's slashed the U.

Moody’s downgraded the United States’ credit rating on Friday, and Wall Street is now bracing for the fallout. The downgrade dragged America down one notch from its top-tier rating. It was the final confirmation that the federal government’s $36 trillion debt is now impossible to ignore.