US stocks rallied Monday on positive news about a potential vaccine for the coronavirus.

In early trading, the Dow Jones Industrial Average gained 766.57 points, or 3.23 percent, to 24,457.10. The S&P 500 gained 2.68 percent. The Nasdaq Composite advanced 1.94 percent.

Shares of Moderna, a company that has been working on a vaccine for the coronavirus, jumped 21 percent.

Moderna's early-stage human trial for a coronavirus vaccine produced antibodies in all 45 participants, the biotech company said Monday.

In the 43rd day of the trial, or two weeks after participants received a second dose, levels of antibodies were generally at levels seen in blood samples from people who recovered from the disease, the company announced.

"When combined with the success in preventing viral replication in the lungs of a pre-clinical challenge model at a dose that elicited similar levels of neutralizing antibodies, these data substantiate our belief that mRNA-1273 has the potential to prevent COVID-19 disease and advance our ability to select a dose for pivotal trials," Tal Zaks, Moderna's chief medical officer, said in a statement.

The US economy could contract as much as 30 percent in the second quarter but won't plunge into a Depression like the 1930s, Federal Reserve Chairman Jerome Powell believes.

In an interview with CBS News program "60 Minutes" on Sunday, Powell the strength of the US financial system and the nation's dynamic economy likely will produce a solid rebound despite an unemployment rate that could climb as high as 25 percent.

"I think there's a good chance that there will be positive growth in the third quarter, and I think it's a reasonable expectation that there will be growth in the second half of the year," Powell said.

"I would say though we're not going to get back to where we were quickly. We won't get back to where we were by the end of the year. That's unlikely to happen."

Powell said shrinkage of the US economy "could easily be in the 20s or 30s (percent)" but the situation differs from the Great Depression because the Federal Reserve has taken steps to support the economy and Congress has approved nearly $3 trillion in emergency funding. The House has passed and the Senate and is about to debate a second stimulus package.

About 36.5 million people have filed unemployment claims in the last two months. The unemployment rate is 14.7 percent and almost certain to go higher.

West Texas Intermediate crude, the gauge for US prices, rose 10.43 percent to $32.50 a barrel, the first time futures traded above $30 a barrel since March. Brent crude, the worldwide benchmark, rose 6.71 percent to $34.67 a barrel. The price of oil is a proxy for future economic activity. Rising prices reflect optimism.

Jack Ma, co-founder of Chinese e-commerce site Alibaba, resigned from SoftBank Group's on Monday shortly before SoftBank announced its largest annual loss ever.

Softbank lost $12.7 billion for the fiscal year ended March 31 compared with a profit of $19.6 billion a year ago. The loss was driven by SoftBank's investment in WeWork, a shared-space office company, and other technology enterprises hit had by the coronavirus.

In a related action, Softbank is exploring the sale of a large percentage of its T-Mobile shares to controlling shareholder Deutsche Telecom, The Wall Street Journal reported.

Softbank apparently seeks to raise money because of the loss. T-Mobile is valued at about $120 billion. The Journal said talks are preliminary and no agreement has been reached. If completed, the deal would boost Deutsche Telecom's stake in T-Mobile above 50 percent.

Apple plans to re-open stores this week in California, Colorado, Florida, Hawaii, Oklahoma, and Washington state, The New York Times reported.

While some stores in those states will remain closed, the announcement is a sign of a gradual return to business.

Recently, the company has started to reopen stores in Australia, Austria and South Korea.

In March, Apple closed about 450 stores, including nearly every location outside China to combat the spread of the coronavirus. Stores in Canada and Italy will remain closed.