The fiscal impasse in Washington continued to weigh on stock prices on Monday, as the market’s “fear gauge,” the C.B.O.E. volatility index, jumped 15.95 percent to its highest level since June. Nonetheless, the market reaction to date has been muted compared with past crises.

“We all tell ourselves, ‘This is something that is not going to happen,’ ” said David Coard, the head of fixed-income trading at the Williams Capital Group. “This would be like a black swan event — it’s not something that you would have thought that the U.S. could do in a million years.”

But the relative calm on Wall Street is worrying some investors, who fear the markets will not signal to politicians the true danger of hitting the debt ceiling until it is too late.

“The markets are sending this complacent message, and I think the politicians are interpreting it incorrectly and they have no sense of urgency,” said Douglas Kass, the owner of the hedge fund firm Seabreeze Partners Management.