Concerns about flagging global growth weighed heavily on Asian stocks Thursday, while European markets opened flat. Japan’s Nikkei index dropped more than 2 percent Thursday before recovering some of those losses, which came after steep declines Wednesday in American and European equities.

Those market drops followed a spate of developments signaling a slowing economy both in the United States and abroad. On Tuesday, Federal Reserve officials warned that the pace of recovery in the United States had slowed. Then on Wednesday came news from China suggesting its fast-growing economy was cooling. And later that day, the Bank of England reduced its already diminished forecast for the British economy.

Finally, new trade figures from Washington showed that American exports were faltering, a sign that hard-pressed domestic manufacturers could not rely on overseas markets to ease their pain at home.

Those reports sent the Dow Jones industrial average tumbling in a 265-point decline, moving it back into the red for the year. The broad market fell 2.8 percent. And those declines carried into Asia on Thursday morning.

The optimism that had pervaded Wall Street only weeks ago has faded quickly. In its place is a growing realization of what many Americans have been feeling in their bones: this is not the economic recovery the nation had hoped for. While the economy is growing again, it is growing too slowly to create many jobs or to increase household incomes.

Given the uneven rebound in the United States, and now signs that the world’s other economic engines are slowing, economists say Americans may confront high unemployment and lackluster growth for some time to come.

“This is going to be a long slog,” said David H. Resler, the chief United States economist at Nomura Securities International.

The trade report from the Commerce Department, which showed exports fell in June, prompted economists to sharply reduce their estimates of how fast the economy had been growing this year.

With the Chinese economy slowing, and European governments tightening their belts to bring down worrisome budget deficits, the fear is that the United States economy will get far less help from overseas than many people had expected.

Without that lift from abroad, and with domestic spending moribund, the American economy is gradually losing steam. Growth is slowing quarter by quarter. In the final three months of 2009, the economy grew at an annual rate of 5 percent. Growth then slowed to a 3.7 percent pace in the first quarter of 2010, then 2.4 percent in the second quarter.

But after downward revisions to other economic data like inventories and the export figures, even that 2.4 percent annual rate is now looking too rosy — and may even be as low as 1 percent, some economists say.

The financial markets — stocks as well as bonds — have begun to adjust to the reality that growth is slowing not only in the United States but in many parts of the world. The reaction Wednesday was swift and painful, with stock markets around the world suffering their biggest setbacks since June.

The Dow Jones industrial average fell 265.42 points, or 2.49 percent, to 10,378.83, while the Standard & Poor’s 500-stock index dropped 31.59 points, or 2.82 percent, to 1,089.47. The Nasdaq fell 68.54 points, or 3 percent, to 2,208.63. Trading was relatively light, which exaggerated the decline.

With Wednesday’s decline in U.S. equities markets, the Dow has once again wiped out all of its gains for the year. It is down nearly 0.5 percent so far in 2010, while the S.& P. 500 is off 2.3 percent. The Nasdaq is down about 2.7 percent.

As stocks declined, investors once again rushed for safety in government debt like United States Treasury securities, driving benchmark market interest rates to their lowest levels in more than a year. Bonds extended their gains from Tuesday when the Fed announced that it would use the proceeds of its huge mortgage-bond portfolio to buy long-term Treasury debt in an effort to keep rates low and encourage growth. The yield on 10-year Treasury notes — a benchmark for many home mortgages and corporate loans — fell to 2.68 percent, from 2.76 percent late Tuesday.

Investors now expect interest rates to remain low for months, if not years. Government bond yields fell even more sharply in overseas markets as signs emerged of a slowdown in growth there.

Caught in the crosswinds was the dollar. It had fallen over the last two months on investors’ expectations that the rest of the world was growing more rapidly than the United States, but it reversed course on Wednesday, at least against the euro. After declining more than 10 percent against the yen in the last three months, the dollar dropped further to 84.72 yen on Wednesday, the lowest level since April 1995, before stabilizing Thursday.

Nigel Gault, the chief United States economist for IHS Global Insight, said the June trade deficit, combined with other data, placed the economy “on even shakier ground than it seemed, and underlining why the Fed has shifted towards an easing bias.”

The Commerce Department said the trade deficit widened to $49.9 billion in June, the largest gap since October 2008. Exports fell by 1.3 percent.

In China, several government indicators, including industrial output, retail sales and bank lending, slowed slightly in July, the government said. The data provided a fairly consistent snapshot of a country where economic growth remained the strongest in the world, but where the manic spending of the last few months had started to fade.

In Britain, the Bank of England cut its economic growth forecast, predicting annual growth to peak at 3 percent, less than the 3.6 percent it had predicted as recently as May. It blamed the uncertain pace of the recovery in the United States and the rest of Europe and reluctance by banks to increase lending.

Tom di Galoma, head of United States rates trading at Guggenheim Capital Markets, said the Fed’s move on Tuesday underscored how concerned policy makers were about the state of the economy — a concern ordinary Americans and, increasingly, Wall Street now share.

“There is certainly a lot of angst about when this recovery is going to take shape,” Mr. di Galoma said.

Keith Bradsher and Catherine Rampell contributed reporting.