Frank Quattrone could face a maximum of 25 years in prison

The jury in the trial of former US investment banker Frank Quattrone is deadlocked after spending much of the day listening again to key testimony and e-mails from the former star of the dot.com boom.

Mr Quattrone, one of the men who profited most from the stock market boom of the 1990s, is charged with trying to obstruct official investigations into the Wall Street flotations of technology shares.

During the dot.com boom, Mr Quattrone made vast amounts of money both for himself and for Credit Suisse First Boston (CSFB) bank by bringing companies including Amazon and Cisco Systems to market.

Jurors at the Manhattan federal court have been deliberating since Wednesday, and still are unable to reach a verdict.

District Judge Richard Owen sent them away for the weekend and said he would issue fresh instructions on Monday.

"My summary is that you are in substantial disagreement on the issues of this case,", he said.

"I know you are all trying as hard as you can."

Innocent people do not ordinarily need to offer false statements to explain away their conduct Assistant US Attorney Steven Peikin

Credit Suisse First Boston (CSFB) paid $100m (�60m) to settle charges it had wrongly given shares in internet flotations to favoured clients in return for banking fees.

Mr Quattrone is alleged to have sent an email to colleagues advising them to "clean up" old files relating to these Initial Public Offerings (IPOs), shortly after being told CSFB was under criminal investigation.

He faces a maximum penalty of up to 25 years in prison if convicted, but is likely to serve less.

"All or nothing"

Lead defence attorney John Keker has said the email from Mr Quattrone was "no big deal."

Later Mr Keker called the government's case "made for TV soap opera".

He told jurors his client's stance was "all or nothing" and that they were not seeking compromise verdicts on the three criminal charges.

Mr Quattrone denies that he obstructed an investigation by America's stock exchange regulator, the Securities and Exchange Commission (SEC).

But in his closing argument, Assistant US Attorney Steven Peikin told jurors that Mr Quattrone had been "argumentative" and "insisted on rephrasing things" during his cross-examination.

He added: "Innocent people do not ordinarily need to offer false statements to explain away their conduct."

Internet flotations

Mr Quattrone made large amounts of money for himself and for CSFB bank in the late 1990s.

As head of CSFB's Global Technology Group, he handled shares in sought-after new listings by hi-tech firms.

He is said to have earned himself at least $200m (�120m) during the boom, while bringing in fees for CSFB of more than $1bn.

CSFB later paid $100m (�60m) to settle charges that it had wrongly given shares in so-called "hot" internet flotations to favoured clients in return for banking fees.