Swedish prosecutors declined to reveal the exact number of suspected victims in the case.
"There are more companies and authorities affected, but the charges cover those in the charge sheet. We selected the most clear-cut cases early on," investigator Helena Ljunggren told a press conference on Monday.
Eight people face trial in connection with the case, which involves at least 40 million kronor ($5 million).
The main suspect's lawyer, Jan-Anders Hybelius, told the TT news agency that his client admits several of the fraud allegations, but claims that he acted on other people's instructions: "The money did not go to him. His financial compensation was very modest, the way I see it."
His 38-year-old client is the only one who is accused of data breach attacks, which he denies. The other seven are accused of having been involved to varying extents in the fraud incidents, according to Ljunggren.
In most cases the data breaches were carried out with the help of e-mail attachments opened by individuals, reports TT. The fraud incidents were allegedly committed when the perpetrators broke into computer systems to send payments to the wrong recipients.
The investigation covers aggravated more than a dozen fraud incidents amounting to around 25.5 million kronor and fraud attempts of 15 million kronor. TT reports that the money was sent to accounts in Sweden and then transferred to other accounts, sometimes registered in Sweden and sometimes abroad.
Investigators have been able to trace some of the money to Kosovo and Hong Kong.
Around 20 companies, four banks, several law firms and a number of private individuals are among those affected, as well as the Swedish Prison and Probation Service.
Banking giant Swedbank was made to pay out 4.3 million kronor in the most serious of the fraud attempts, but the money has been secured, according to prosecutor Ljunggren.
According to the Kvällsposten daily, the Gekås superstore in Ullared, Ikano Bank, Resurs Bank, payment startup Klarna and construction firm NCC are also among those targeted.
The Sweden Democrat party said they had also received e-mails from the group, but did not think they had fallen victim to financial fraud. "Unfortunately these kinds of e-mails are quite common in society and we have procedures for how to handle them," said the party's press officer Henrik Vinge.
The trial starts on September 26th in Malmö.