US authorities have charged nine members of an alleged international hacking and insider trading ring, the BBC understands.
The group, operating in the US and Ukraine, allegedly netted more than $30m (£19m) in illegal profits.
Hackers are accused of accessing data being processed by financial “wires” in order to obtain information about companies before it was made public.
The information was then used to buy and sell shares, the indictment says.
Five of the individuals have been arrested and are in custody in the United States, an FBI spokeswoman confirmed.
The releases were allegedly accessed on the servers of financial wire firms Business Wire, Marketwired and PR Newswire.
In an indictment filed at the district court of New Jersey, prosecutors alleged that “the defendants accessed more than 150,000 stolen releases and executed profitable trades based on the material nonpublic information contained in the stolen releases”.
It added: “In total, the scheme generated more than $30m in illicit trading profits.”
The alleged hacking is said to have occurred over the past five years and included a “phishing” attack, in which the employees of Marketwired were allegedly sent an email containing a link to malware.
In this case, the company successfully identified the phishing attempt and prevented an intrusion.
The indictment also includes allegations of malware covertly installed on PR Newswire’s servers and of login details stolen from Business Wire.
An official announcement regarding the charges will be made at 16:30 BST.