The suspect was arrested on Wednesday (July 7th) in the eastern Swiss canton of Graubuenden by police acting on an arrest warrant from German authorities, the Swiss justice ministry said.

The ministry did not name the suspect, but AFP learnt from sources speaking on condition of anonymity that he is Berger.

The man is challenging his extradition to Germany, the ministry said, adding that the case was being examined.

He is believed to be the mastermind behind the fraudulent scheme, and acted as a middleman for investors involved in the scam.

German prosecutors have accused Berger of serious organised fraud. If convicted, Berger risks up to 10 years in prison.

First exposed in 2017, the scam involved numerous cooperating participants quickly exchanging stock in companies amongst themselves around dividend day, in order to claim multiple tax rebates on a single payout.

Used across Europe, this practice cost Germany €7.2 billion ($8.5 billion), Denmark €1.7 billion and Belgium €201 million since 2001, according to European media outlets including German broadcaster ARD.

Around 100 people have been indicted over the scandal, including bankers, stock traders, lawyers and financial consultants, according to daily Frankfurter Allgemeine Zeitung.