Wall Street tumbled today after the government reported a jump in unemployment that was much larger than the market anticipated and as oil prices surged more than $6 a barrel. The Dow Jones industrial average gave up more than 240 points.

The decline in stocks also helped drive bond prices sharply higher as investors sought a more secure place for their money.

The Labor Department said the nation’s unemployment rate rose to 5.5% in May from 5.0% in April. The rate, logging its biggest monthly rise since February 1986, is now at its highest level since October 2004. Wall Street, on average, had predicted an uptick to 5.1%.

The number of American jobs shrank by a smaller-than-expected 49,000, but that figure offered Wall Street only a little solace given that May marked the fifth straight month of jobs losses. Signs that the American job market is deteriorating more than anticipated could thwart investors’ hopes that the economy is poised for recovery later this year — a belief that has helped drive the stock market higher over the past couple months.

Employment data are important to investors because when Americans lose their jobs — or fear that they might — they tend to pare discretionary spending. Already, consumers are spending less due to soaring food and energy prices, and oil’s ascent today added to the market’s trepidation. A slowdown could deal a big blow to the economy as consumer spending accounts for more than two-thirds of American economic activity.

Crude oil has made an aggressive rebound this week, rising more than $7 a barrel in two days after falling amid a drop in demand for gasoline. Light, sweet crude jumped $5.91 to $133.70 a barrel on the New York Mercantile Exchange after reports that a Morgan Stanley shipping analyst predicted oil would jump to $150 a barrel by July 4.

In midmorning trading, the Dow fell 240.19, or 1.91%, to 12,364.26.

Broader stock indicators also declined. The Standard & Poor’s 500 index fell 20.72, or 1.48%, to 1,383.33, and the Nasdaq composite index fell 37.93, or 1.49%, to 2,512.01.

Today’s pullback comes a day after the Dow jumped nearly 214 points, showing its largest daily point gain since April 18 following better-than-expected sales from retailers and a dip in jobless claims. The good economic news helped investors shrug off the more than $5-a-barrel spike in oil prices. But the further advance in oil on today appeared too much for investors to overlook.

Bond prices moved higher after the weak jobs data. The yield on the benchmark 10-year Treasury note, which moves opposite its price, fell to 3.97% from 4.04% late yesterday.

The dollar declined against other major currencies — a move that makes each barrel of oil more expensive. Gold prices rose.

Declining issues outnumbered advancers by more than 3 to 1 on the New York Stock Exchange, where volume came to 189.6 million shares.

The Russell 2000 index of smaller companies fell 11.10, or 1.45%, to 752.17.

Overseas, Japan’s Nikkei stock average closed up 1.03%. Britain’s FTSE 100 fell 0.22% in afternoon trading, Germany’s DAX index fell 0.88%, and France’s CAC-40 declined 1.22%.