The bank says it will not try to recover the whole sum, but it will claim any money Kerviel received from book or film contracts.
The "affaire Kerviel" exploded in early 2008, at the beginning of the global financial crisis. Kerviel, a junior trader, was found to have made huge one-way trades on the direction of European stock markets.
He was supposed to make simultaneous "bets" on stock exchange futures going up and down to make modest amounts of money on tiny margins between the two.
Instead, he "faked" covering trades and hacked into computers to defuse the bank's internal safeguards.
At his trial in 2010, and at the appeal hearings, Kerviel and his lawyers admitted he had "lost all sense of reality". But they called a string of witnesses who said he was also a victim of a greedy financial system which had itself lost touch with reality. While Kerviel was winning, they said, the bank tacitly approved his dealings.
When he got into trouble, he was made a scapegoat for the bank's wider losses in the financial crisis.
Kerviel's lawyer, David Koubbi, described the verdict as "an absolutely lamentable miscarriage of justice". He said his client would consider a further appeal. Kerviel remains free until that decision is made.
Counting the losses
Ongoing: The trial of Kweku Adoboli has reached its sixth week. The 32-year-old former trader at Swiss bank UBS is accused of causing losses of US$2.3 billion and faces four criminal charges.
February 2009: Alexis Stenfors, former senior trader at Merrill Lynch, was banned from working in the City after admitting he deliberately overvalued his trading positions to hide losses of US$100 million.
February 1995: Barings, one of Britain's oldest investment banks, collapsed after Nick Leeson, a futures trader in Singapore, lost £860 million in derivatives trading. He was jailed in Singapore.
- Independent