Stocks surged in the final minutes of trading on Monday, snapping back from one of the worst weeks for global markets since the 2008 financial crisis as investors seized on promises that the world’s governments would step in to help if the global economy was slammed by the outbreak of the coronavirus.

The S&P 500 jumped 4.6 percent, the biggest single-day leap since late December 2018. The rally followed news that central bankers from the world’s biggest economies would join a conference call with Group of 7 finance ministers on Tuesday to discuss a response to the outbreak, fueling expectations among investors that governments might lower interest rates in tandem.

“It has already stoked expectations of a coordinated cut,” Roberto Perli, a former Fed researcher who is now an economist at Cornerstone Macro, said in an email. “If it doesn’t happen, it will only add to market volatility.”

But Mr. Perli did not see it as a sign that a simultaneous cut with other global central banks was necessarily coming. Nor did Seth Carpenter, another former Fed researcher, now at UBS. “The rally in equities today has perversely probably made it easier for the Fed to sit back and wait to see what happens,” he said in an email.