NEW YORK (AP) — In Wall Street's tug of war between hope and pessimism about the coronavirus pandemic, hope is pulling back. U.S. stocks joined a worldwide rally Friday and closed out their first back-to-back weekly gain since the market began selling off two months ago.

The S&P 500 jumped 2.7% Friday, following up on even bigger gains in Europe and Asia, as investors latched onto several strands of hope about progress in the fight against the coronavirus. They included the White House's release of guidelines for states to reopen their economies and a very early but encouraging report on a possible treatment for COVID-19.

The gains came even as scary data piled higher about the economic and human toll of the virus, which has killed more than 150,000 worldwide and forced the formerly high-flying Chinese economy to shrink a crunching 6.8% last quarter. A measure of leading economic indicators in the U.S. plunged last month by the most in its 60-year history, the latest in a string of similarly unprecedented data reports.

The S&P 500 rose 75.01 points to 2,874.56. The Dow Jones Industrial Average jumped 704.81, or 3%, to 24,242.49, and the Nasdaq added 117.78, or 1.4%, to 8,650.14.

"There's no clear path yet" on when the pandemic and the economic devastation it's caused will end, said Lindsey Bell, chief investment strategist at Ally Invest.

That's caused the stock market to cycle up, down and up again, sometimes in the same day, as it tries to set prices now for where corporate profits will be months in the future.

Optimists have been more forceful recently as they point to infections leveling off in some hard-hit areas. That raises the possibility that parts of the economy could reopen, even if it's not tomorrow, and an eventual pickup in profits. Optimists are willing to look through all the economic damage in the near term, which is being mitigated somewhat by massive aid from the Federal Reserve and the U.S. government.

"Just having that light at the end of the tunnel is what people really want to see," said J.J. Kinahan, chief market strategist at TD Ameritrade.

Pessimists say the recent rally for stocks has been overdone and point to the severe pain shocking the health care system and the economy. They say conditions are unlikely to get back to anything approximating "normal" soon. Even the unprecedented aid from the Fed and Congress won't be nearly enough for households and businesses to weather a protracted downturn.

"We're trying to bridge from the current state to the aftermath, and that bridge is just not long enough," said Eric Freedman, chief investment officer at U.S. Bank Wealth Management. "That's the bearish case, that consumers are impacted beyond what the policy can provide because the virus extends and people really hold off on making more expenditures."

Among the wisps of optimism that investors were focusing on Friday:

— A news report cited early progress in a drug candidate for the virus. Analysts cautioned that the encouraging data was only anecdotal, and they were hesitant to put too much stock in it. Shares of the company behind the candidate, Gilead Sciences, surged 9.7%.

— Boeing said late Thursday that it will resume production of passenger jets in Washington state next week. It suspended work late last month after workers tested positive for the coronavirus. Its 14.7% surge was a big reason for the Dow's climb Friday.

In a sign of a bit less caution in the market, Treasury yields ticked higher but remain extremely low. The yield on the 10-year Treasury rose to 0.64% from 0.61% late Thursday, though it remains well below the 1.90% level it was near at the start of the year. Bond yields drop when their prices rise, and investors tend to buy Treasurys when they're worried about the economy.

"The government can give the mandate to reopen the economy, but it's going to be all about how comfortable consumers feel in going back to their workplace and how comfortable they feel about going back to restaurants or doing other activities around other people," said Ally Invest's Bell. "The best way for us to get any insight into that is to listen to what corporations say about how they're going to bring back their workforce. Is it going to be at a 25% rate? A 50% rate?"

Investors could hear such commentary in upcoming weeks, with hundreds of CEOs scheduled to discuss how badly their profits got hit by stay-at-home orders in the first three months of the year.

The market's gains were widespread Friday, across all 11 sectors that comprise the S&P 500. Energy producers and banks led the way, a sharp turnaround from their laggardly ways earlier in the week when worries about the economy were at the forefront.

The S&P 500 has more than halved its loss since February's high. After being down as much as 34% in March, it's rallied and is now down only about 15%.

In European trading, the CAC 40 in Paris rose 3.4%, while Germany's DAX climbed 3.1%. Britain's FTSE 100 added 2.8%.

Japan's Nikkei 225 index jumped 3.1%, the Hang Seng in Hong Kong advanced 1.6% and South Korea's Kospi leaped 3.1%.

India's S&P BSE 100 rose 2.8% after the central bank cut its benchmark interest rate to help the stalled economy and ease financing troubles amid a nationwide lockdown to fight the pandemic.

"Human spirit is ignited by the resolve to curb the pandemic," said Reserve Bank of India Gov. Shaktikanta Das. "It is during our darkest moments that we must focus on the light."

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AP Business Writer Elaine Kurtenbach contributed