Idris Dayo Mustapha, a 33-year-old British-Nigerian, has acknowledged that he was the mastermind behind a sophisticated seven-year cyber fraud scheme.
Mustapha was a major player in a hacking ring that targeted US corporate email and brokerage accounts between 2011 and 2018, causing significant losses that topped $6 million (£4.7 million).
US authorities had been pursuing Mustapha for several years.
His crimes carry a jail term of up to 20 years.
Mustapha pleaded guilty plea at a court in Brooklyn, New York, on Tuesday to four charges: computer intrusion, securities fraud, wire fraud, and access device fraud, the BBC reported.
Authorities say Mustapha and his ring hacked into the computer servers of financial institutions in the US to access confidential user data, such as users’ personal identifying information.
They then used the stolen information and passwords to transfer funds and securities from the accounts of their victims to accounts under their control.
They also used the hacked accounts to conduct stock trades without the knowledge of the account holder.