Wall Street is preparing to reopen after shutting for four working days following the attacks on the World Trade Centre in the heart of the city's financial district.
Treasury Secretary Mr Paul O'Neill will officially reopen the markets at the end of a two-minute silence to remember the thousands killed.
The closure was believed to be the longest since the First World War and the Securities and Exchange Commission invoked its emergency powers for the first time to ease the reopening of the equities markets.
"These markets are the world's strongest and most vibrant, in spite of the heinous acts of last Tuesday," a spokesman said.
The New York Stock Exchange was reopening amid tight security and employees were told they should not report for work unless specifically told to do so, and that identification would be checked rigorously.
Wall Street and the Nasdaq reopening has been nervously awaited by traders across the world after volatile trading followed the terrorist attacks.
The FTSE 100 Index slumped 187.9 points on Friday, wiping about £44 billion from the value of shares, and trading tomorrow was expected to show continuing nerves.
The reopening of the financial district around Wall Street posed difficulties for city officials as it is only some five streets from the World Trade Centre site, which is still sealed off as a crime scene and where rescue attempts and the clearance of mountains of debris continues.
There were also safety fears because of the thick smoke, dust and rubble in the area, particularly reports that the dust contained asbestos.
New York city officials said the air quality around Wall Street did not mean that people had to wear breathing masks, but they said there would be limits on where people would be allowed to walk once the area reopened.
PA