A former hedge fund manager who wore a wire to help build a massive New York insider trading case has been spared a prison sentence after prosecutors called his cooperation exceptional.

Thomas Hardin was sentenced Wednesday to time served — a brief period he was in custody before an initial court date years ago. He says he's "incredibly humbled and ashamed" by his crimes.

Hardin pleaded guilty to conspiracy and securities fraud in 2009.

By then, he already was helping Manhattan federal prosecutors piece together a web of interlocking insider trading circles. Ultimately, about two dozen people pleaded guilty or were convicted, including billionaire hedge fund founder Raj Rajaratnam (rahj rah-juh-RUHT'-nuhm).

Prosecutors say Hardin gave information about people including investor Roomy Khan. She became an important witness against Rajaratnam and others.

Rajaratnam had argued the government improperly wiretapped his phone.