The trial is taking place in Munich's largest and newest courtroom, a bomb-proof underground hall built in the Stadelheim prison complex.
Braun, an Austrian born in Vienna, has denied embezzling money from Wirecard and accused others of running a shadow operation without his knowledge.
[1/8] Wirecard's former CEO Markus Braun looks on at a courtroom as his trial begins, after the German payments company collapsed in the wake of a fraud scandal in 2020, in Munich, Germany, December 8, 2022.
The fraud let Wirecard managers siphon money out of the company with no proper checks and balances.
"All three defendants worked together to make Wirecard appear as an extremely successful FinTech company," said Anne Leiding, a spokesperson for the prosecutors.