A Wall Street billionaire who once headed a large investment firm has been sentenced to 11 years in prison and fined $10 million in an insider stock trading scandal.

A U.S. federal judge, Richard Holwell, on Thursday imposed the sentence on Raj Rajaratnam, a 54-year-old Sri Lanka native who helped start the now-defunct Galleon Group investment fund. The judge said that Rajaratnam's crimes reflected “a virus in our business culture that needs to be eradicated.”

Rajaratnam was convicted in May of 14 counts of conspiracy and insider stock trading — illegally using confidential corporate information in order to make huge sums of money by buying or selling the companies' stock. Judge Holwell said he had concluded that Rajaratnam had made more than $50 million from his trading on the illicit information. More than two dozen other people have also been convicted in the case.

Rajaratnam's sentence is one of the longest ever imposed in a U.S. insider stock trading case. Prosecutors had sought a sentence of more than 19 years. But the judge credited Rajaratnam for his charitable ventures over the years, while noting that he suffers from diabetes and needs a kidney transplant.