By Akane Otani and Joe Wallace 

Investors puzzling over conflicting signals about the health of the global economy that sent markets sliding in recent trading will get a new set of clues this week in the form of key economic data from the U.S. and other wealthy nations.

Fourth-quarter gross domestic product readings from the U.S., U.K., France and Canada could enlighten the debate over whether the global economy is in the midst of a temporary dip or headed toward a more serious downturn.

The U.S., which releases a revised fourth-quarter GDP estimate Thursday, is of special concern to investors looking for signs that a slowdown in global growth is worsening. Economists at JPMorgan Chase expect a revised GDP estimate of 1.8%, well below the 2.6% growth estimate released by the Bureau of Economic Analysis a month earlier.

A considerably lower U.S. GDP estimate would suggest that the world's largest economy is more vulnerable than previously thought, intensifying fears of a broader slowdown.

Worries about global growth have set financial markets in the U.S. and Europe on edge. For much of this year, major stock indexes had climbed, lifted by signs that central banks would put aside their rate-increase campaigns for the foreseeable future. But that relief has seemingly given way to fear.

Following further downbeat economic data from Europe on Friday, investors say they are grappling with the possibility that the global economy's momentum is worsening faster than they had expected.

"You have some concerns out there about big political issues like Brexit and the U.S. trade dispute with China, neither of which are being resolved and both of which even seem to be deteriorating," said Larry Hatheway, head of investment solutions and chief economist at GAM Investments.

"Now there's a sense that what's happening elsewhere -- that the U.S. won't be completely immune to it, even though it's a more closed economy and is on a stronger footing," he said.

In one sign of the growing pessimism, traders have begun betting the U.S. Federal Reserve will not only have to hold rates steady but lower them to support the economy. Federal-funds futures on Friday showed the market pricing in a 56% chance of at least one rate cut in 2019, compared with 11% one month ago, according to CME Group.

In another sign, the yield on 10-year German government bonds fell below zero Friday for the first time since 2016. Meanwhile, the yield on the 10-year U.S. Treasury note slipped to its lowest since the start of 2018.

Much of the market's pivot appeared to begin Friday, after data pointed to a worse-than-expected pullback in eurozone manufacturing activity, amplifying concerns about the health of the European economy. Major indexes on both sides of the Atlantic slumped to end the week.

The moves underscored concerns about whether central banks' easy-money policies will be enough to avert a deeper pullback, many say.

On one hand, data in the U.S. continue to point to an economy that remains on strong footing. Sales of previously owned homes soared in February at the fastest pace since 2015, data released Friday showed. Corporate earnings are expected to grow overall for the year, and labor market figures show businesses hiring at a healthy clip.

But economies across Europe and China have shown signs of further deterioration, leaving investors wondering whether weakness there could eventually have a ripple effect around the world.

"Expectations of a strong stock market seem to be ebbing," said George Gero, managing director at RBC Capital Markets.

To be sure, some of the market moves Friday may have stemmed from investors taking profits after a long streak of stock gains, money managers said.

The S&P 500 remains up 12% for the year, on course for its best quarterly gain since 2012. Stock indexes in Europe, Hong Kong and Shanghai also are logging double-digit percentage gains.

The steep slide in bond yields also may have been exaggerated by investors unwinding bets on their rise, said Mr. Hatheway, who added that he didn't intend to pick up government debt that still looked "very, very expensive."

Still, with few signs that economic momentum is set for an imminent rebound, the market rout could intensify, other investors cautioned.

Christopher Stanton, chief investment officer at Sunrise Capital Partners, purchased futures contracts on Thursday that would rise in value if market volatility shot higher, as it did on Friday. Mr. Stanton believes the volatility is likely to continue as investors question whether central banks will be able to sufficiently boost economic growth in a slowdown.

"It seems like the market is coming to the conclusion that the Fed has backed itself into a corner," he said.

The challenges central bankers face appear to be even more severe in the eurozone given its greater exposure to China and reluctance to raise government spending, strategists said.

The European Central Bank has limited power to boost growth there given that monetary policy remains extremely loose, said Alain Bokobza, head of global asset allocation and equity strategy at Société Générale.

In contrast, the Fed appears to have plenty of firepower: its target short-term interest rate is well above zero, he said, but it has signaled it will only take meaningful action if there is a very bad batch of data.

Still, some investors are holding out hope that economic activity, while looking set to lose some momentum in the first half of the year, will perk up in the second half -- supporting further gains for markets.

Michael Kelly, global head of multiasset at PineBridge Investments, expects the current global slowdown won't last much longer than the end of spring. Beijing has taken action to halt China's downturn, and U.S. companies that have delayed investment during the trade conflict will put spending plans into action if there is a resolution, he said.

"If markets are weak again next week, we could be on the buy side," Mr. Kelly said.

--Ira Iosebashvili contributed to this article

Write to Akane Otani at akane.otani@wsj.com

(END) Dow Jones Newswires

March 24, 2019 16:27 ET (20:27 GMT)