The stock markets in New York have reopened after their longest closure since 9/11 due to the superstorm Sandy.
Mayor Michael Bloomberg rang the bell at the New York Stock Exchange and, after early gains, the Dow Jones index closed down 11 points at 13,096.
Sandy flooded the subway and submerged much of Lower Manhattan near the financial district.
The cost of clearing up after the storm is estimated to be in the region of $30-40bn (£18-24bn).
The technology-heavy Nasdaq also opened after being closed for two days, and finished little changed, up just 2 points at 2,988. It is the first time the weather has shut the stock markets for two consecutive days since 1888.
"The finance capital of the world is open for business," Mr Bloomberg tweeted as he opened trading.
Some analysts are concerned that the length of time that the markets have remained closed could lead to the backlog of pending trades overwhelming the system.
"You build up pressure when you keep people out of the markets," said Mark Travis, president of Intrepid Capital Funds.
"Trading volume that may normally happen in a two-day period could get compressed into an hour or two when markets reopen."
NYSE said it is using backup generators - for the first time - because power is out in much of downtown Manhattan.
It added that one of its key data centres in New Jersey was in good condition.
NYSE Euronext chief executive Duncan Niederauer said the exchange systems were working smoothly.
Businesses in the city are slowly getting back to normal. The two biggest international airports, JFK and Newark Liberty, are scheduled to open for a limited service on Wednesday.
Beyond New York City, public transport has been halted in several eastern US cities. Eight million people have no power and 18,000 flights have been cancelled.