17 September 2026 marks 25 years since US equity and options markets reopened after the terrorist attacks of 11 September 2001. The attacks caused severe disruption to New York’s financial infrastructure and led to the closure of the markets.

In the days that followed, regulators, exchanges, intermediaries and infrastructure providers worked to test systems and restore connectivity. The Securities and Exchange Commission recorded that US equity and options markets reopened on Monday, 17 September 2001.

The SEC reported that trading resumed without major incident and that, before the reopening, there had been extensive testing of systems and connections between market participants. The moment had both an economic and a symbolic dimension: functioning markets were an important part of US financial infrastructure.

Reopening did not mean an immediate return to normality. Markets reflected uncertainty and the economic consequences of the attacks, and institutions continued to deal with logistical and operational problems. The events of September 2001 also prompted a broader reassessment of business-continuity planning and the resilience of financial infrastructure.

We do not repeat here the chronology of the attacks. RoAdevăr has documented the 25th anniversary of 11 September in a separate article. What remains here is a fact of market history: the longest interruption of trading on Wall Street in recent decades ended on a Monday, after tests and coordination among the regulator, the exchanges and intermediaries.

Twenty-five years after the reopening of 17 September, the episode remains a landmark in the modern history of US financial markets and of how they respond to major crises.

Photo: the New York Stock Exchange building, 27 April 2012. Photograph by Jean-Christophe BENOIST, CC BY 3.0, via Wikimedia Commons.

Source consulted: US Securities and Exchange Commission — Market Recovery following September 11.