The 23 suspects allegedly made stock market trades worth millions of dollars based on advance knowledge of corporate takeovers.
The companies involved were not named in a statement issued by German prosecutors from the south-western state of Baden-Wurttemberg.
The swoop was instigated by German financial regulator BaFin, which had found new evidence on an initially unsuccessful 2008 investigation.
More than 150 police, eight prosecutors and 20 BaFin officials took part and confiscated documents, data storage devices, computers and mobile phones.
The suspects, aged 32 to 64, were allegedly friends, former work colleagues and members of the same clubs. If found guilty, they face up to five years in jail.