U.S. stocks fell Wednesday, adding to their losses after concerns over the Ukraine crisis helped push the S&P 500 into correction territory.

The U.S. stock benchmark declined 0.6%, a day after closing down more than 10% from its Jan. 3 record following Russia’s deployment of soldiers in Ukraine’s Donbas region.

The Dow Jones Industrial Average...

U.S. stocks fell Wednesday, adding to their losses after concerns over the Ukraine crisis helped push the S&P 500 into correction territory.

The U.S. stock benchmark declined 0.6%, a day after closing down more than 10% from its Jan. 3 record following Russia’s deployment of soldiers in Ukraine’s Donbas region.

The Dow Jones Industrial Average fell 0.3%, or about 110 points, and the technology-heavy Nasdaq Composite retreated 0.9%.

The consumer discretionary sector weighed on the S&P 500, falling 1.7%, while the communication services and technology groups also declined. Energy stocks defied the trend, rising 0.9%.

The threat of war in Ukraine has added to uncertainty in global markets. On Wednesday, Ukraine declared a state of emergency and began to mobilize reservists, calling on its citizens to immediately leave Russia.

Investors say the effects on stock and bond markets are hard to predict. The implications depend on rapidly moving diplomatic and military developments as well as the possible spillover of higher energy prices into inflation in Western economies.

Money managers already were grappling with looming interest-rate increases by the Federal Reserve and other major central banks. Some analysts say they are continuing to focus on developments around monetary policy.

“Geopolitical events tend to spike volatility,” said Michael Antonelli, market strategist at Baird. “They tend to be noisy. Those aren’t real signal. The real signal in the stock market is what the Fed is doing and what interest rates are doing.”

As Russia ordered troops to two breakaway regions in Ukraine, Germany halted the certification of the Nord Stream 2 pipeline. Uncertainty over the project, which would allow Russia to bypass Ukraine to export natural gas to Europe, is affecting prices. Photo composite: Eve Hartley

On Tuesday, the U.S. laid out an initial round of sanctions against Moscow for what President Biden

called the start of an invasion of Ukraine. The European Union, the U.K. Canada, Australia and Japan also imposed or proposed restrictions on Russian companies, individuals and financial markets.

“Until the market sees boots on the ground we may not see the reaction that maybe we would have expected,” said Brian O’Reilly, head of market strategy at Mediolanum Asset Management. “We’re probably now in a wait-and-see mode to see how this develops.”

Mr. O’Reilly added that data pointing to strong economic growth was helping the stock market largely take the crisis in its stride. Private data firm IHS Markit said Tuesday its composite Purchasing Managers Index for the U.S. rose to a two-month high in February, suggesting the economy gained momentum.

Among individual stocks, Lowe’s rose 2.4% after the retailer logged higher sales and earnings in its fourth quarter. Shares of Overstock.com jumped 21% after the company beat earnings expectations.

TJX Cos. shares fell 8.1% after the retailer missed expectations for sales and earnings.

In the bond market, the yield on 10-year Treasury notes rose to 1.962% from 1.947% Tuesday. Yields move in the opposite direction as bond prices.

The threat of war in Ukraine has added to the uncertainty in global markets.

Photo: Allie Joseph/Zuma Press

Overseas, the pan-continental Stoxx Europe 600 slipped 0.2%. The Shanghai Composite Index rose 0.9%, while Hong Kong’s Hang Seng added 0.6%.

Oil prices steadied after rising earlier in the week in response to Russia’s troops deployment. Brent crude, the global oil benchmark, was up 1% to $97.80 a barrel. Natural-gas futures in Europe extended their advance after Germany put the Nord Stream 2 pipeline, which runs directly from Russia, on hold Tuesday.

Among European stocks, Dutch drinks company JDE Peet’s rose 15% after saying its profit doubled last year as coronavirus-induced restrictions were lifted. Barclays

advanced 3.4% after the London-listed bank said its net profit rose.

Write to Joe Wallace at joe.wallace@wsj.com and Karen Langley at karen.langley@wsj.com