Broad S&P 500 lost 0.6 percent, Nasdaq's technology-heavy composite index fell 0.5 and Dow Jones industrial index closed at minus 0.7 percent.
Regional banks acted as a drag. Bank group Zions plummeted 13.1 percent, after the bank announced a loss of $50 million during the third quarter related to two borrowers.
Bank Western Alliance also plummeted, down 10.8 percent, after news of credit problems related to the same borrowers.
In the background to what the banks describe as individual incidents, a concern is simmering on Wall Street that bad loans, not least on the more obscure private credit market, may create greater turmoil in the financial systems.
The shutdown of the US government apparatus is also in its third week. Investors are also weighing the risks that the trade conflict with China may flare up again.
