A tourist takes photos in New York's Times Square as news streams by announcing that the Dow Jones industrial average closed down 416 points. On Tuesday, stocks had their worst day of trading since the Sept. 11, 2001, terrorist attacks.

Market experts said that a stunning slide in major stock indexes that began Tuesday may continue for a while, perhaps lasting several weeks. But they said the drop wasn’t unexpected given that during its recent spectacular rise, the Dow Jones industrial average, the symbol of the market for many Americans, has gone without a 2 percent decline for the longest stretch in more than 47 years.

Barely a week after dazzling investors by reaching a new all-time high, major stock indexes Tuesday suffered their worst plunge in more than five years because of a combination of misfortunes. Falling Chinese and European stock markets, combined with worries that the U.S. economy might be slowing more than expected, drove the Dow down more than 546 points before it recovered to end the day down 416 points, or 3.29 percent, at 12,216.24.

The market’s woes also were exacerbated by technical glitches. Right before 3 p.m., stocks fell 178 points in one minute when Dow Jones, which calculates the Dow, switched data servers because its computers couldn’t keep up with heavy trading. Additionally, around 3:30 p.m., the New York Stock Exchange experienced what spokesman Richard Adamonis called a “capacity problem.” Certain specialists and floor brokers received more orders than the system could handle, he said.

The Standard & Poor’s 500 index, a broader gauge of U.S. market health than the 30-stock Dow, fell nearly 3.5 percent, and the Nasdaq Composite Index, loaded with technology shares, plummeted nearly 3.9 percent.

The slide was the worst since Sept. 17, 2001, when U.S. markets opened for the first time since the Sept. 11 terrorist attacks.

Beginning in China shortly after that country’s government announced measures that would crack down on speculation, it spread to Europe and then infected U.S. markets the minute they opened, with investors trying to get out of their positions ahead of the sell-off.

“It’s a game of musical chairs,” Irwin Kellner, chief economist for North Fork Bank and Weller professor of economics at Hofstra University. “Once anybody gets a hint that the music is about to stop, they all dive for the chairs.”