Mr Quattrone made his name during the technology boom

The ex-analyst at CSFB in New York was convicted of blocking an investigation into alleged kickbacks for directing share offerings to choice clients.

His 18-month sentence is on appeal, but the NASD, the organisation in charge of the US securities industry, has now banned him for life.

Mr Quattrone was one of the stars of the dotcom era, first at Morgan Stanley and then - from 1998 - at CSFB.

But in 2000 regulatory and criminal probes began into whether CSFB and other banks had "spun" shares in hot issues, assigning them to favoured clients who could then sell them at a fat profit.

Mr Quattrone told his staff in a December email that it was "time to clean up those files" - a statement which prosecutors said showed he was trying to destroy evidence.

A first trial into whether he had blocked investigations produced a hung jury. The second jury found Mr Quattrone guilty, but he continues to protest his innocence.

The NASD ban follows Mr Quattrone's refusal to talk to it before the criminal trial.

The refusal was "egregious", the NASD said.