It seemed, by many accounts, a far happier day than the last.

Hours after their worst drop since 1987, stocks reversed course on Tuesday and headed right back up on hopes that lawmakers were nearing an agreement on a bailout for the financial system. The Dow industrials jumped 485.21 points, erasing more than half its loss from Monday. Bank stocks rose sharply, investors were lured out of Treasury bonds, and the dollar soared.

But alarms were sounding elsewhere in the byzantine channels of the global financial system, sending a clear message that the health of the world’s economy remained at risk of worsening.

Even as President Bush and Congressional leaders worked to make a rescue plan palatable to lawmakers, the flow of credit neared a standstill, making it more difficult for businesses to obtain the money they need for routine expenses like utilities and payroll. Banks were still reluctant to lend, despite billions of dollars of cash offered up by central banks around the world. Early on Tuesday, banks were charging one another the highest overnight borrowing costs ever recorded, as measured by an important rate known as Libor.

Even the triple-digit stock rally, spurred by investors’ hopes that Congress will approve a revised version of a bailout plan, represented yet another of the big daily swings that reflect fragility and fear.