But not only has Roger Duronio, 60, of New Jersey been charged with using the logic bomb to cause more than $3 million in damage to the computer network at UBS's stockbroking unit Paine Webber, he has also been charged with securities fraud for his failed plan to drive down the company's stock with activation of the logic bomb.

Duronio was employed as a systems administrator in UBS Paine Webber in New Jersey where he was paid a salary of $125,000. The court heard that he had been expecting a bonus of $50,000, but when he only received $32,000 Duronio decided to take revenge on the bank and began constructing the logic bomb computer program.

Duronio resigned from the company on 22 February 2002 and on March 4 2002 his program activated and began deleting files on over 1000 of UBS PaineWebber's computers. Around 17,000 UBS traders across the US were unable to trade shares for more than a day because of the damage.

But furthermore, in the month before the logic bomb went off, Duronio spent more than $21,000 on 318 put option contracts, so if UBS shares fell in value following the network failure, Duronio would make a profit.

Duronio is charged with securities fraud, which carries a maximum penalty of 10 years and a $1 million fine, and computer fraud which carries a maximum prison sentence of 10 years and a fine of $250,000, or two times the gain made by the defendant or the loss suffered by the victim.

Commenting on the case, US Attorney Christopher Christie says cybercrime against financial institutions is a 'significant' issue: "Although the damage was contained in this case, the potential for catastrophic damage in other cases is always there. We will prosecute cyber criminals and put them in prison."

Earlier this week, UBS attempted to have the case heard in secret, arguing it could expose details of the company's IT systems, but the request was rejected by Judge Joseph Greenaway.

The case is expected to last three weeks.