A 33-year-old British-Nigerian man Idris Dayo Mustapha has admitted to orchestrating a sophisticated cyber fraud scheme spanning seven years.
Mustapha, a key member of a hacking ring, targeted email and brokerage accounts of US corporations from 2011 to 2018, resulting in substantial losses exceeding $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.