Islamic State claimed responsibility for suicide bomb attacks in the Belgian capital that killed at least 30 people, with police hunting a suspect who fled the air terminal.
Travel sector stocks, including airlines and hotels, were among the hardest-hit, although equities managed to recover from sharp losses and bonds and gold eased from their early highs.
On Wall Street, the NYSEArca airline index <.XAL> lost 0.9 percent and was on track for its first decline in five sessions. Cruise ship operators Royal Caribbean (>> Royal Caribbean Cruises Ltd), down 2.9 percent and Carnival Corp (>> Carnival Corp), down 2.1 percent, were among the worst performers on the S&P 500.
Those declines were offset by gains in Apple (>> Apple Inc.), up 0.8 percent to $106.72 and a 0.9 percent gain in the healthcare <.SPXHC> sector.
"The news obviously has been dominated by what has gone on in Brussels, but experience tells us not only is it the morally right thing to do to basically not overreact, it also turns out to be the most profitable thing to do," said David Kelly, chief global strategist at JPMorgan Funds in New York.
"The objective of terrorists is to disrupt and, to the extent that they can, do horrible things but at least we have the small victory that they have not disrupted global financial markets today."
The Dow Jones industrial average <.DJI> fell 41.3 points, or 0.23 percent, to 17,582.57, the S&P 500 <.SPX> lost 1.8 points, or 0.09 percent, to 2,049.8 and the Nasdaq Composite <.IXIC> added 12.79 points, or 0.27 percent, to 4,821.66.
The FTSEuroFirst 300 index <.FTEU3> of leading shares closed down 0.12 percent at 1,338.20, rebounding from a 1.6 percent drop. Belgian stocks <.BEL20> rose 0.17 percent after having been down as much as 1.4 percent. MSCI's index of world shares <.MIWD00000PUS> edged down 0.03 percent.
In Europe, the STOXX Europe 600 Travel & Leisure index <.SXTP> was down 1.8 percent. Shares in major European airlines like Ryanair (>> Ryanair Holdings plc) and Air France-KLM (>> Air France-KLM) also fell.
Volume is expected to continue to diminish ahead of the Easter holiday, and investors were beginning to think about cashing in on a steep rally in stocks over the last few weeks.
Gold <XAU=> was up 0.31 percent at $1,248.10 an ounce after hitting a high of $1.259.60 earlier.
Benchmark U.S. 10-year notes <US10YT=RR> were last down 6/32 in price to yield 1.9403 percent after falling as low as 1.879 percent as Chicago’s Federal Reserve president struck a bullish tone on the U.S. economy.
In currency markets, the Japanese yen, regarded by investors as a shelter from turbulence, pulled back from early gains, notably against the euro. The euro was last up 0.14 percent at 126.01 yen <EURJPY=> and the dollar turned positive, up 0.3 percent at 112.27 yen <JPY=>.
The euro <EUR=> fell 0.16 percent against the dollar to $1.1221. The dollar <.DXY> was up 0.33 percent to 95.606 against a basket of major currencies.
Oil prices also steadied after the initial rush to safer assets, with U.S. crude <CLc1> settling down 0.17 percent to $41.45 a barrel while Brent rebounded from a low of $40.97 to settle up 0.6 percent at $41.79.
(Reporting by Chuck Mikolajczak; Editing by Nick Zieminski and Dan Grebler)
By Chuck Mikolajczak