He provided evidence for dozens of insider trading convictions.
Rajaratnam is serving an 11-year sentence after his 2011 conviction. His younger brother, Rengan, was acquitted of conspiring to engage in insider trading last year, ending a five-year winning streak for Bharara’s office.
Prosecutors said Hardin traded in shares of companies including Hilton Hotels HLT , Google GOOG , and Kronos based on illegal tips from Roomy Khan, a key figure in the Galleon case who also pleaded guilty and cooperated.
Hardin told Swain that he was “deeply humbled and ashamed” by his conduct but that he hoped he had made amends through his assistance.
“The actions that brought me here today were selfish, reckless and inexcusable,” he said.