The situation in Ukraine has only played into those fears.

Ukraine makes up only about 0.2 percent of global gross domestic product, according to Société Générale, and in itself has little bearing on the world economy. Rather, economists said the biggest danger to global growth, outside of outright war, was the possibility that sanctions or political theater could bring a disruption to the flow of natural gas to Western Europe, creating an external shock that could push the fragile euro zone back into recession.

The crisis has energy markets worried because a large portion of Russian natural gas for Europe moves through Ukraine. Natural gas prices rose about 6 percent on the British market, and shares of Gazprom, the Russian gas monopoly that counts Ukraine as a major customer, fell more than 10 percent. Oil prices also rose, with Brent crude futures traded in London adding 1.9 percent. What may be keeping prices from going higher for now is that in recent years Russia has chipped away at the amount of gas that goes through Ukraine by opening the Nord Stream pipeline, which bypasses the country. In addition, European countries have been able to build up substantial stores of gas, given that the winter has been warm.

Stocks with direct exposure to Russia and Ukraine also took a hit.

Several of the biggest western oil companies like ExxonMobil and Royal Dutch Shell have major investments in Russia. BP, the British oil company, has significant interests with a 20 percent stake in Rosneft, the state-controlled oil company. Robert W. Dudley, BP’s chief executive, serves on Rosneft’s board, and BP has been in talks to send teams of technical experts to help the Russian company. On Monday, BP shares fell 2 percent in London.

Russia is also a big player in industrial metals, and most of the world’s major brands are significantly invested in the country. “That means Russia is very important for a range of European and American companies,” said Chris Weafer, co-founder of Moscow-based Macro Advisory. For instance, Russia is the No. 1 market for the French dairy giant Danone and the second-biggest market for Pepsi. Shares of the French automaker Renault, which also has major operations and sales there, fell 5.4 percent.

European banking shares were broadly off, led by a 9.6 percent decline in Raiffeisen Bank International, the Austrian lender that ranks as one of the Western lenders most exposed to Ukraine. UniCredit, the Italian lender, fell 6 percent, while BNP Paribas of France and Piraeus Bank of Greece each declined more than 3 percent.

But the fallout to the banking sector may be somewhat limited. During the financial crisis in 2009, many Western banks pulled back from Ukraine, and Russian lenders, particularly Sberbank and VEB, stepped in to take up the slack. Raiffeisen is one of the few European Union lenders with major Ukraine business, and it said in November that it was seeking to sell the local unit, known as Raiffeisen Bank Aval.