The New York Mercantile and Commodity exchanges closed at 1pm because emergency ventilators were unable to sustain the trading floors at one of three smaller buildings in the complex that suffered relatively little damage.
The exchanges obtained special permission over the weekend to reopen for business, while the two 110-storey towers and the Vista Hotel - charred by smoke damage from underground fires - will remain closed this week.
The towers house 900 businesses, including one large Wall Street firm, two primary US government bond dealers, the largest inter-dealer bond brokerage, a big international accountancy firm and the US headquarters of two of Japan's big banks.
Some firms moved into branch offices in New York and suburban New Jersey, and others flew staff and redirected phone lines to subsidiaries across the country.
Dean Witter Discover, the centre's largest private tenant, transferred 4,500 employees to six offices around the city, while Dai- Ichi Kangyo Bank and Yamaichi Securities moved to Jersey City across the Hudson River.
The World Trade Centre carries about dollars 600m worth of property insurance and another dollars 400m of casualty insurance, and estimates of business losses are running into billions of dollars.Reuse content