NEW YORK — What a difference a week makes.

Seven days after closing at record levels on the back of a strong employment report, the stock market slumped to its worst weekly loss in two and a half years. The catalyst for the sell-off was an extension of a rout in oil prices.

Oil plunged Friday for the fourth time in five days after the International Energy Agency said global oil demand will grow less than previously forecast next year. The price of oil fell 12 percent for the week, going below $60 per barrel on Thursday for the first time since July 2009. Oil has now fallen 47 percent since reaching a peak of $107 in June this year.

A debate is raging among analysts and investors over whether tumbling oil prices are a net advantage or a detriment to the economy and the stock market. While consumers benefit from lower gas prices, energy companies will take a hit as their earnings are crimped. Those companies will also spend less on plants and equipment, hurting their suppliers.

Investors are also starting to worry whether the slump in demand for oil is signaling that growth outside of the U.S. is weaker than had been thought. The last time oil prices were this low was when the U.S. economy was emerging from the Great Recession.

“In a nation like the U.S. (as well as) Europe and most of Asia, the benefits of falling oil outweighs the costs,” said Jeff Kleintop, Schwab’s chief global investment strategist. “The concern is that there’s something more to it, given such a sharp decline, that there’s something deeper here.”

The Standard & Poor’s fell 33 points, or 1.6 percent, to 2,002.33. The index dropped 3.5 percent in the week, its biggest drop since May 2012.

The Dow Jones industrial average dropped 315.51 points, or 1.8 percent, to 17,280.83. The Nasdaq composite dropped 54.57 points, or 1.2 percent, to 4,653.60.

After flirting with a close above 18,000 just one week ago, the Dow has now shed more than 700 points after being weighed down by big losses in Exxon Mobil and Chevron.

Stocks started the day lower after a report showed that growth in factory output in China, the world’s second-largest economy, declined last month.

The data came after Chinese leaders affirmed their commitment to the “new normal” of slower growth as they try to steer China toward a more sustainable expansion based on domestic consumption.

U.S. benchmark oil dropped $2.14, or 3.6 percent, to $57.81 a barrel. Brent, the international benchmark, lost $1.83, or 2.9 percent, to $61.85 a barrel. Energy stocks in the S&P 500 index fell 2.1 percent, taking their loss for the year to 16.5 percent.

Some companies bucked the downward trend.

Adobe reported fourth-quarter results late Thursday that beat Wall Street expectations. Adobe also said it will pay $800 million to buy the stock image and video company Fotolia. The stock jumped $6.28, or 9 percent, to $76.02.

Government bond prices rose. The yield on the benchmark 10-year Treasury note, which falls when prices rise, dropped to 2.08 percent from 2.17 percent Thursday.

The dollar fell. The U.S. currency dropped 0.2 percent to 118.74 yen. The euro rose 0.5 percent against the dollar to $1.24593.

In metals trading, silver fell six cents, or 0.3 percent, to $17.06 an ounce. Gold dropped $3.10, or 0.3 percent, to $1,222.50. Copper rose a penny, or 0.4 percent, to $2.93 a pound.

In other futures trading:

• Wholesale gasoline fell 2.7 cents to close at $1.597 a gallon.

• Heating oil fell 4.5 cents to close at $2.016 a gallon.

• Natural gas rose 16.1 cents to close at $3.795 per 1,000 cubic feet.

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