Wall Street. The Dow has another roller-coaster day to finish its worst week in 2 years. »

The markets have their worst week in two years as stocks struggle to stabilize.

A late-afternoon rally reversed steep losses for U.S. stocks Friday, lifting the Dow Jones industrial average more than 300 points and capping a turbulent week on Wall Street that left the market with its steepest weekly slide in two years.

The big point swings that pummeled stocks reflected a return of volatility after an unprecedented period of calm. Until this week, the market had not endured a 5 percent drop since January 2016.

“There’s a fair amount of volatility in the market, and our belief is the volatility is leaving investors riddled with stress and uncertainty, which is likely to continue,” said Terry Sandven, chief equity strategist at U.S. Bank Wealth Management.

The swiftness of the market’s slide into a correction, or a drop of at least 10 percent from a recent peak, was unparalleled. The Standard & Poor’s 500 index, the benchmark for many index funds, took only nine days to fall 10 percent from its all-time high on Jan. 26. “The S&P 500 hasn’t moved into correction mode this quickly, ever,” said Lindsey Bell, investment strategist at CFRA Research.

Since hitting that high last month, the S&P 500 has lost about $2.49 trillion.

For a while Friday, it was anybody’s guess whether the weeklong sell-off would ease or worsen. Stocks struggled to stabilize much of the day as investors sent prices climbing, then slumping in unsteady trading a day after the market entered its first correction in two years.

The Dow Jones briefly sank 500 points after surging more than 349 points earlier in the day and then swung to a 330-point gain in the final hour of trading. The blue chip average suffered its second 1,000-point drop in a week on Thursday.

All told, the S&P 500 rose 38.55 points, or 1.5 percent, to 2,619.55 Friday. The Dow gained 330.44 points, or 1.4 percent, to 24,190.90. The Nasdaq composite added 97.33 points, or 1.4 percent, to 6,874.49.

The three indexes finished the week down more than 5 percent.

Technology companies accounted for most of the broad gains.

Bond prices also fell. The yield on the 10year Treasury rose to 2.86 percent from 2.83 percent late Thursday.

Benchmark U.S. crude lost $1.95, or 3.2 percent, to settle at $59.20 per barrel on the New York Mercantile Exchange. Oil has not been below $60 a barrel since Dec. 28. Brent crude, used to price international oils, slid $2.02, or 3.1 percent, to close at $62.79 in London.