How many trading days did the New York Stock Exchange close after the September 11 attacks?

The New York Stock Exchange closed for four trading days after the September 11 attacks.

U.S. stock exchanges remained closed from Tuesday, September 11, 2001, through Friday, September 14. Trading resumed on Monday, September 17, the longest closure since the Great Depression-era shutdowns caused by World War I disruptions.

When the market reopened, the Dow Jones Industrial Average fell 684.81 points, or 7.13%, its largest one-day point decline at that time. Selling continued during the week as investors assessed the attacks’ effects on airlines, insurance companies, tourism, and the broader economy.

The closure was necessary because communications and financial infrastructure in Lower Manhattan had been damaged, while authorities also faced security and operational concerns. The market’s reopening was carefully coordinated among exchanges, regulators, and financial institutions.