Hedge fund billionaire Raj Rajaratnam has been found guilty of insider dealing, becoming the highest-profile scalp in the history of such investigations in the US. He now faces up to 20 years in prison.

The 53-year-old co-founder of the Galleon group was found guilty of 14 charges of securities fraud and conspiracy after a trial in New York.

Prosecutors accused the Sri Lankan-born billionaire of making $63.8m (£39m) from tips by corporate insiders and hedge-fund traders, and used controversial surveillance techniques to secure the conviction.

Rajaratnam was arrested in October 2009 and the government's investigation has widened to other hedge funds, so-called expert network firms, banks and technology companies. Some 19 people have pleaded guilty in the investigation.

The eight women and four men of the jury took 11 days to reach a verdict. Their decision was delayed after one juror was excused on medical grounds and a replacement had to be brought in.

The trial began on 8 March and involved some of the biggest names in US business. Rajaratnam was the most prominent corporate prosecution since the credit crunch. Unlike fraudster Bernard Madoff, Rajaratnam maintained he was innocent and assembled a high-powered defence team.

Goldman Sachs boss Lloyd Blankfein was called to give evidence after prosecutors alleged former Goldman director Rajat Gupta had leaked confidential information.