BNP Paribas' results were hit by a record U.S. fine in July, which helped tip the bank to a 4.32 billion euro ($5.76 billion) loss in the second quarter.
The French bank said the impact of one-off items was "very significant", and highlighted its huge $9 billion settlement with U.S. authorities for breaching sanctions against dealing with Sudan, Cuba and Iran.
Excluding exceptional items, net profit came in at 1.9 billion euros in the three months between April and June 2014.
Prosecutors had accused BNP Paribas of processing billions of dollars through the U.S. financial system on behalf of the Sudanese, and others barred because of human rights abuses, support for terrorists and other security concerns.
"We observed what went wrong," Lars Machenil, chief financial officer at BNP Paribas, told CNBC early Thursday. "We definitely regret what happened. We settled with U.S. authorities. In particularly, we took industrial steps to make sure it never happened again."
In its results statement this Thursday, CEO Jean-Laurent Bonnafé said BNP Paribas had "learnt lessons from these past events and is implementing a major reinforcement of its internal control".
Analysts at Citi said the bank's headline loss was as expected. They rate its stock a buy, with a price target of 61.00 euros.
Follow us on Twitter: @CNBCWorld