The former Societe Generale trader accused of losing 5bn euros ($7bn; £3.5bn) has been released from custody.
Jerome Kerviel spent five weeks in jail before Tuesday's court decision to release him under strict conditions.
The investigation into SocGen's huge losses continues. The bank says Mr Kerviel used inside knowledge to cover up unauthorised trades.
But an internal report by the bank also said that SocGen's oversight of traders was not vigilant enough.
Societe Generale announced the trading losses in late January. Shortly afterwards, Mr Kerviel turned himself in to police.
Prosecutors accused him of breach of trust, fabricating documents and illegally accessing computers.
Last month, they won a court order to have Mr Kerviel jailed, arguing that he might undermine the investigation by talking to others caught up in the probe.
A court on Tuesday reversed that ruling, but strict conditions remain on Mr Kerviel's freedom.
He is not allowed to be active in the financial markets or leave the Paris region without permission.
He cannot meet anyone connected with the investigation and has to present himself weekly at a police station.
SocGen's internal investigation concluded that Mr Kerviel had started making unauthorised trades in 2005, initially for small amounts.
But by the time SocGen uncovered the trades in January, the trading position had hit 49bn euros.
SocGen was forced to reverse those trades in unfavourable market conditions, resulting in huge losses.
The report also said that Mr Kerviel acted alone.