The longest weather-related shutdown of U.S. stock trading since 1888 ended Oct. 31 without incident, while underscoring how vulnerable the world's biggest financial market remains to disasters.

Duncan Niederauer, the chief executive officer of NYSE Euronext, said trading went smoothly as American equity markets came back to life after a 48-hour hiatus forced by Hurricane Sandy. Trading was suspended three days earlier when concerns about human safety and how well the New York Stock Exchange's backup plan would work convinced executives that moving ahead was too risky.

The Securities and Exchange Commission may consider whether exchanges' emergency regimens need to be bolstered, according to a person familiar with the regulator's thinking who asked not to be named because the matter is private. The industry's decision to halt equities and bond trading shows the challenge of maintaining markets when a catastrophe threatens New York City, home to 168,700 securities industry workers.