Big second thoughts.

As more details of the plan emerged, and it became apparent that the $700 billion package would not sail through Congress at light speed, investors' fears resurfaced. As Congress battled over details, Federal Reserve Chairman Ben Bernanke and Treasury Secretary Henry Paulson were preparing their sales pitch on the rescue proposals in testimony in front of the Senate Banking Committee on Tuesday.

Want some more second thoughts?

The prospect of a massive binge of borrowing by the Treasury to fund the plan sent the U.S. dollar sharply lower on Monday. A lower dollar typically goes hand in hand with higher commodity prices, and gold and oil surged Monday. The yellow metal moved back above $900 per ounce and oil hit $130 per barrel before retreating. The resurgence in oil prices was especially worrisome as a sustained rise in energy prices could increase pressure on a shaky U.S. economy.

Amid all these morning-after ruminations, investors apparently had some second thoughts about the recent market rally. And some high profile stock repurchase announcements from brand-name companies Monday failed to dissuade them from dumping stocks.

On Monday, the blue-chip Dow Jones industrial average plunged 373.23 points, or 3.28%, to 11,015.21. The broader S&P 500 index dropped 47.96 points, or 3.82%, to 1,207.12. The tech-heavy Nasdaq composite index plummeted 94.92 points, or 4.17%, to 2,178.98.

Action in the broader market was negative. On the New York Stock Exchange, 24 stocks declined in price for every seven that gained. The ratio on the Nasdaq was 20-7 negative. Trading was sluggish.

Market activity has been extremely volatile of late, with several 300-plus point movements in the Dow industrials in the past week.

There were no major economic reports scheduled for release Monday.

Investors on Monday were coming to grips with the magnitude of the government's bailout plan, and new developments in financial markets.

"On Friday, the Treasury, SEC and Fed finally opened the taps wide to halt a financial meltdown of historic proportions, and initiate an era that will likely include a substantial deployment of financial market re-regulation," wrote Action Economics chief bond market strategist Michael Wallace.

The bailout plan encountered some resistance Monday. Reuters reports Senate Democrats issued a counterproposal to the Treasury Department's $700 billion Wall Street bailout plan that would give the government a stake in firms unloading assets under the plan, and limit the pay of corporate executives involved.