He was staying at the team's L'Arrivée hotel in Dortmund on the day of the attack and had moved to a room on the top floor, overlooking the street where it took place, prosecutors said.
North Rhine-Westphalia state interior minister Ralf Jäger said the suspect "appears to have wanted to commit murder out of greed".
Police in Germany have arrested and charged a man suspected of being behind the attack on the Borussia Dortmund team bus on April 11.
Borussia Dortmund coach Thomas Tuchel has said the arrest of the man apparently responsible for this month's bomb attack on the team bus before a Champions League game could help players and staff overcome the trauma."If the motive has been identified that would help us a great deal to process it", Tuchel said at a news conference previewing Dortmund's Bundesliga match at Borussia Mönchengladbach on Saturday. He faces charges of attempted murder, causing an explosion and serious bodily harm. On the day of the attack he bought 15.000 BVB put-option shares, without getting to much into the details of stock exchanges, in laments terms those put-option shares would have allowed him to make a lot of money if the BVB-stock would have fallen significantly.
"A significant share price drop could have been expected if a player had been seriously injured or even killed as a result of the attack", they said.
Marc Bartra was injured in the blast.
Sergej. W had allegedly taken out a loan of tens of thousands of euros to pay for the put options, most of which he purchased online from the IP address of the hotel, prosecutors said. He would have profited from the transaction if the price for shares of the team fell.
The club thanked authorities in a statement.
Chief Executive of the Borussia Dortmund, Hans-Joachim Watzke, said that the club would be improving the security of its team, adding that they were considering bringing in measures to restrict the trading of its shares.
The fact that, aside from Bartra and the policeman, "no others were wounded or even killed, was - as we know today - exclusively due to huge luck", BVB said in its statement Friday.
After the three identical notes claiming responsibility for the attack were found at the scene, investigators initially considered the possibility that it might have been the work of Islamic extremists.