4 p.m.: Stocks fell on Monday and Treasuries rose, after Congressional inaction on a multi-trillion dollar stimulus bill outweighed yet another wave of promised monetary policy support from the Federal Reserve.

The Dow Jones Industrial Average closed slightly off its lows of the day, down 582 points, or 3%. The S&P 500 fell 2.9% and the Nasdaq Composite slipped 0.3% after briefly rising into the green in the early afternoon. All three indexes are coming off of their worst week since the depths of the financial crisis in early...