Specialist Mario Picone, right, watches the numbers Friday as he works on the floor of the New York Stock Exchange. The Dow Jones industrial average has plunged more than 530 points amid a global sell-off.

NEW YORK — Growing concerns about a slowdown in China shook markets around the world on Friday, driving the U.S. stock market to its biggest drop in nearly four years.

The rout started in Asia and quickly spread to Europe, battering major markets in Germany and France. In the U.S., the selling started early and never let up. Investors ditched beaten-down oil companies, as well as Netflix, Apple and other technology darlings. Oil plunged below $40 and government bonds rallied as investors raced into hiding spots.

“Investors are wondering if growth isn’t coming from the U.S. or China, where is it going to come from?” said Tim Courtney, chief investment officer of Exencial Wealth Advisors. “This is about growth.”

By the time it was over, the Standard and Poor’s 500 index had lost 5.8 percent for the week, its worst weekly slump since 2011. That leaves the main benchmark for U.S. investments 7.7 percent below its all-time high — within shooting range of what traders call a “correction,” a 10 percent drop from a peak.

Markets began falling last week after China announced a surprise devaluation of its currency, the yuan.

On Friday, the Standard & Poor’s 500 index dropped 64.84 points, or 3.2 percent, to close at 1,970.89.

The Dow Jones industrial average fell 530.94 points, or 3.1 percent, to 16,459.75. That’s 10 percent off its high, a correction.

That’s unwelcome news for anyone with a 401(k) invested in stocks, but they shouldn’t panic and try to time the market’s swings, said Quincy Krosby, market strategist for Prudential Financial.