The blasts shattered the bus windows, leaving Spanish international Marc Bartra, 26, with a wrist injury.
The blasts shattered the bus windows, leaving Spanish international Marc Bartra, 26, with a wrist injury. A police officer also suffered inner ear damage in the April 11 assault.
The suspect -- named only as Sergei W. -- was arrested 10 days after he allegedly set off three explosive devices hidden in a hedge as the bus was leaving the team hotel for a Champions League match.
Investigators had initially feared a jihadist link after letters purportedly suggesting an Islamist motive were found at the scene.
But questions quickly arose over their authenticity and an Iraqi man taken into custody was soon cleared of involvement.
Days later, police swooped on W., an electrical technician, charging him with 28 counts of attempted murder, causing explosions and serious physical injury.
His financial motive then emerged.
W. was staying in the same Dortmund hotel as the players, had a view of where the bombs went off and had bought so-called put options on the team's shares on the day of the attack, prosecutors said.
Dortmund, also known as BVB, is the only football club in Germany that is listed on the stock exchange.
For his money-making scheme, W. had apparently taken out around 50,000 euros ($59,000) of credit to finance the purchase of options.
They could have been sold at a pre-determined price by June 17, more than two months after the attack, when a sharp fall in the share price would have promised a high profit.
Prosecutors said "a significant drop in the price could have been expected if, as a result of the attack, players had been seriously injured or even killed".
The suspect could have pocketed up to 500,000 euros in profit if the plan came off, they believe.
W. however sold the options in the days after the attack, making just 5,900 euros.
The head of Germany's criminal police unit, Holger Muench, said: "We have never experienced such an attack that turned out in the end to be such a perfidious form of stock market manipulation."
W. faces life in prison if found guilty, although in Germany parole is usually granted after 15 years.
Citing unnamed investigators, Bild said police believed the suspect was capable of building a remotely-triggered bomb, having won an educational award in electronics and engineering in 2005.
Prosecutors say the bombs each contained up to a kilogram of a hydrogen peroxide fuel mixture and around 65 metal studs.
W. drew attention at the hotel, reported Bild, first by insisting on a window room facing the front and then, in the pandemonium after the blasts, by calmly walking into its restaurant to order a steak.
Dortmund lost their postponed game against Monaco a day after the attack, prompting then coach Thomas Tuchel to rail against UEFA for not giving the players time to come to terms with their fears before playing the match.