Frank Quattrone could face a second trial

The judge reached his decision on Friday after the jury said for the second day in a row that it was unable to agree on a verdict on any of the three criminal charges.

Jurors had several times sought additional guidance from the judge as they tried to decide if Mr Quattrone knowingly hindered an official investigation into allegations of share "spinning" at Credit Suisse First Boston (CFSB).

Mr Quattrone made his name, and a fortune, as a technology stocks analyst during the dot.com boom in the late 1990s.

Second trial?

Prosecutors have the right to launch another trial against Mr Quattrone on the same charges.

The judge said prosecutors would be meeting him on 5 November for a status report.

Mr Quattrone, who made his name by masterminding the stock market launch of high-profile dot.com era companies including Amazon and Cisco Systems, was accused of advising staff to delete e-mails sought by official investigators.

The investigators were probing allegations that CSFB and other Wall Street banks allocated shares in sought-after internet flotations to favoured clients in return for lucrative investment banking contracts - a practice known as "spinning."

If found guilty, Mr Quattrone could have faced a maximum penalty of 25 years in jail, though federal guidelines recommend a lighter sentence.

State and federal prosectors closed an investigation into CSFB in 2001. The bank paid $100m to settle civil charges without admitting wrongdoing.

Mr Quattrone is said to have made a personal fortune of $200m during the dot.com boom.

He resigned from CSFB in March 2003 after being suspended when the allegations of email-shredding emerged.