By the end of the day, the Dow Jones index fell 59.44 points or 0.29% to 20,591.86, while the S&P 500 was down 8.85 points or 0.38% at 2,344.93.
The tech-focused Nasdaq index dropped 30.61 points or 0.52% to 5,836.16.
Financial stocks did particularly badly ahead of results from Wells Fargo, Citigroup and JPMorgan on Thursday.
The S&P 500 financials index slipped 0.9%, with Wells and Citi losing 1.92% and 0.88% respectively. JP Morgan gained 0.33%.
Shares in United Airlines continued to tumble as boss Oscar Munoz said he would not step down over the forcible removal of a passenger from a flight.
The stock ended 1.10% lower after losing 1% yesterday.
Wall Street shares closed lower on Wednesday amid continuing concern at geopolitical tensions over Syria and North Korea.