But others warned that the problems at the center of the current crisis, including a global credit squeeze and worsening economic conditions, were far from solved, and could set the stage for more volatility in markets.

Reeling from the worst week in stocks since 1933, officials announced over the weekend that they would flood the financial system with billions of dollars in liquidity and provide capital for troubled banks, throwing out the traditional financial playbook in favor of a series of moves that officials hoped would get banks lending again.

Relief poured through the markets. The 11.6 percent gain in the broad Standard & Poor’s 500-stock index was that gauge’s best single-day gain since 1939. Stocks in Paris and Frankfurt had their best single-day gains ever, rising more than 11 percent. The Dow Jones industrial average, which closed at 9,387.61, up 11.1 percent, is now back to its level on Thursday. Only four times in its history has the Dow risen more percentage points in a day. Those gains came in 1929, 1931, 1932, and 1933.

But trading volume was lighter than last week, meaning fewer investors jumped in to buy than were selling last week. Portions of the credit markets  which remained locked tight before the weekend  were closed for the Columbus Day holiday, so investors may have had trouble gauging the reaction among banks and big lenders to the new global initiatives. Some analysts said that stock investors held off on their trades to see how the credit markets would react.

“If the credit markets open up tomorrow and you can’t see money flowing where it’s supposed to flow, you imagine that this whole thing reverses itself quite dramatically,” said Randy Cass, chief executive of First Coverage, a firm that collects and analyzes investment advice offered by brokerage firms.