Trading will resume as planned on Monday

After a successful test of its computer and communications systems on

Saturday, New York Stock Exchange chairman Richard Grasso said trading will

resume as planned on Monday.

The NYSE, Nasdaq and the American Stock Exchange have been shut down since Tuesday, the longest closure of the NYSE since World War I.

With the volcanic-like ash from the twin towers being shoveled away,

allowing financial and other firms to make a "dry run," Grasso said based on

the evaluation of the exchange's systems "at 9.30am (EST) Monday morning trading will resume" as planned.

Officials said that member firms participating in the test were 100% successful in placing orders, and the exchange was able to keep up with 90% of the volume, considered a good rate.

Tests will continue throughout the weekend.

Brokerage employees and exchange officials were bused in for the tests but

all subway stops east of Broadway were open, the mayor said.

A huge U.S. flag hung stretched across all five columns of the building.