Christine Lagarde, the managing director of the International Monetary Fund (IMF), has been convicted of negligence by a special French court for her role in a hugely contentious arbitration award to a businessman in 2008.
But Lagarde, who was France's finance minister at the time, has been spared punishment and a criminal record.
The Court of Justice of the Republic, made up of three judges and 12 parliamentarians, tries cases concerning ministers for alleged crimes while in office.
Lagarde, who was not present for the verdict, maintained her innocence through the week-long trial.
The prosecutor had asked for an acquittal.
The case revolves around a €403m arbitration deal given to tycoon Bernard Tapie in 2008 over the botched sale of sportswear maker Adidas in the 1990s. The amount prompted indignation in France.
Civil courts have since quashed the unusually generous award, declared the arbitration process and deal fraudulent and ordered Mr Tapie to pay the money back.
The Washington-based IMF said after Monday's verdict that its executive board would meet soon "to consider the most recent developments".