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Additionally, traders weighed on the leisure and entertainment industry through the PowerShares Dynamic Leisure and Entertainment Portfolio (NYSEArca: PEJ), which dropped 0.3% Tuesday. PEJ includes a range of resorts, hotels, airlines and cruise ship companies. Similarly, the Market Vectors Gaming ETF (NYSEArca: BJK), which follows casinos and casino hotels, fell 0.9%.

Traders are growing uncertain over the outlook of the travel and tourism industry after Brussels explosions killed dozens in what authorities called a terrorist attack.

“It’s hard to say what the long-term impact is, but it’s not good,” Sanjiv Shah, chief investment officer at Sun Global Investments, told the WSJ. “There are worries about security, the impact on growth, greater restrictions on travel. It’s just more uncertainty.”