The 24-year-old assistant of French rogue trader Jerome Kerviel has been charged with complicity in the multi-billion-euro scandal at Societe Generale, judicial officials have said.
The Societe Generale employee, named as Thomas Mougard, was charged on Friday with “complicity to introduce false data into a computer system,” the official said.
Judges accuse him of “knowingly helping Jerome Kerviel to record fictitious operations” at the bank, in 2007 and January 2008.
One of France's big three banks, Societe Generale shocked the financial world when it announced in January staggering losses of 4.9 billion euros ($A8.22 billion) at the hands of a rogue trader.
The losses were incurred as the bank was forced to unwind more than 50 billion euros ($A83.8 billion) of unauthorised deals Kerviel is said to have made.
Mr Mougard is the second person after Mr Kerviel, 31, to be charged over the biggest rogue trade scandal in banking history.
An internal Societe Generale report made public in May said it found “signs of internal complicity” by Mr Kerviel's assistant.
He had been questioned several times in connection with the mammoth losses as an “assisted witness”, a legal status half way between a simple witness and being charged.
Mr Kerviel turned himself in to police on January 26, two days after the bank revealed the losses, and on January 28 was charged with breach of trust, fabricating documents and illegally accessing computers.
The trader has insisted his managers knew of his dealings but kept silent as long as he was making good returns.