The biggest insider trading trial in more than a decade has started in New York.
Raj Rajaratnam, a Sri Lankan billionaire who founded the hedge fund company Galleon, is accused of making tens of millions of dollars in illegal profits from inside information on stock trades.
Mr Rajaratnam, who was arrested in October 2009, has pleaded not guilty to charges laid against him. He has been free on bail of $US100 million and if convicted, could face more than 20 years in jail.
The trial is expected to feature confidential informants, secret recordings of telephone conversations and some high-profile witnesses, the BBC reports.
Some 150 potential jurors are being questioned by Judge Richard Holwell.
The Securities and Exchange Commission said in its complaint that the case involved "widespread and repeated insider trading" at a number of hedge funds, including Galleon.
According to the financial regulator, the alleged unlawful trading involved the use of inside information on companies including Hilton Hotels and Intel.
Incidents cited in court documents describe the passing of information on takeovers or company results before they were publicly released.
Mr Rajaratnam then traded on that information, often on behalf of Galleon, the SEC alleges. It estimated that the scheme generated $US52 million in "illicit profits or losses avoided".
Mr Rajaratnam founded the Galleon Group hedge fund, which managed about $US7 billion at the time of his arrest. His personal wealth has been estimated at about $US1.3 billion.
More than a dozen people, including employees of some of America's biggest companies, including IBM and Intel, have been criminally or civilly charged in the complex case and 19 have pleaded guilty to date.
Information is the lifeblood of traders. But there is a fine line between acting on rumours and tips, and acting on information that is private, the BBC reports.
The US government hopes this will help redefine that line, which is why this case could change how business is done on Wall Street.