The longest weather-related shutdown of U.S. stock trading since1888 ended Oct. 31 without incident, while underscoring howvulnerable the world's biggest financial market remains todisasters.

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

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