The broker supposedly ripped off a customer through unauthorized trades, then used a forged document to cover up his activities.

Prudential said he was fired for what it contends was an unauthorized trade in the summer of 2001.

Leeson, though, was making huge unauthorized trades during this period.

At least two other traders were involved in making unauthorized trades, he said.

First Capital said its management first learned of the unauthorized trades last week, three years after they started.

Kerviel never denied what he did, which was to bet on stock futures with massive unauthorized trades.

Besides, until recently, clearing firms have generally not been held legally responsible for problems - like unauthorized trades - experienced by their clients' customers.

A rogue trader is an authorized employee making unauthorized trades on behalf of their employer.

However, when he made the unauthorized trades that Merrill said contributed to its $275 million loss last month, he was dismissed.

And a single executive's unauthorized trades in the copper market cost Sumitomo nearly $1.8 billion before they were uncovered in 1996.