Investors agonizing over whether the stock market is bottoming out or about to extend its precipitous decline face more uncertainty this week as they await action on the government's rapidly expanding effort to pull the financial system from the brink.

If last week was any indication, Washington's medicine has yet to take hold. Wall Street suffered through its worst five-day period in history as investor fears about frozen credit markets deepened and they yanked money out of the markets, sending major indexes tumbling from New York to Hong Kong.