Originally Posted by de.wikipedia
On April 21, 2017 the GSG 9 [special police unit] arrested a suspect, suspected to be guilty of 20 counts of attempted murder, effecting a detonation of explosives, and causing dangerous injury. He is the 28-year old Sergej W. of Freudenstadt, who hold German and Russian citizenship, has finished vocational training in electronics, and worked most recently in Tübingen in a heating plant. The investigators surmise that the motive is greed.
According to media reports, the investigators had already observed the suspect since April 13, after an informant from the finance sector as well as a money laundering notice by a bank had informed the officials. [The club] Borussia Dortmund, too, received a notice from a finance service provider about an unusual deal in derivatives of the BVB stock. According to investigators, the suspect had bought 15,000 put options on the club stocks in the late morning of the day of the incident, termed to June 17, 2017. He'd have wanted to exact a plunge in the stock price and earn a fortune on the sell-options, which gain greatly when stocks drop. He is said to have financed the purchase of the options with a five-digit consumer credit. According to calculations by [economics weekly journal] Wirtschaftswoche, the maximum profit was 75,000 Euros, while other media report a six-digit amount. W. reportedly conducted the purchase on the day of the attack from the hotel where the team stayed; additionally, it's considered certain that W. had stayed the night at the hotel. He's said to be very adept with detonation technology.