The authorities said they had been conducting an investigation since November 2021, and that they carried out multiple searches this week and last in Germany, Britain and Austria, seizing evidence that is now being evaluated.
The German man was arrested on Jan. 18 and remains in custody.
Authorities described profits from the alleged trades as a two-digit million euro figure.
Frankfurt prosecutors and BaFin declined to provide further details on the individuals or their employers.
(Reporting by Tom Sims and Marta Orosz, editing by Rachel More, Kirsten Donovan)
