A federal appeals court overturned the conviction on Monday of high-powered technology banker Frank Quattrone, granting him a new trial.

The 2nd U.S. Circuit Court of Appeals in Manhattan said the jury instructions in Quattrone's trial were erroneous.

It also ordered that the case be reassigned to another judge. Quattrone's lawyers said the trial judge, Richard Owen, made inconsistent rulings about evidence and testimony that kept their client from getting a fair trial.

Quattrone was sentenced to 18 months in prison after he was convicted of obstruction-of-justice charges in May 2004.

Quattrone, 50, has been allowed to remain free while he appeals his conviction. A jury found him guilty of obstructing a federal probe into initial public offerings of stock.

Quattrone was one of the biggest names on Wall Street during the 1990s Internet stock boom. The National Association of Securities Dealers has barred him from the securities industry for life.

Quattrone was convicted of hindering a federal probe into how his bank, Credit Suisse First Boston, had allocated shares of initial public offerings of stock during the late-1990s Internet boom.

The banker, who took prominent companies like Amazon.com public during that period, was the highest-profile Wall Street figure since junk-bond pioneer Michael Milken to face a criminal conviction.

In its ruling, the appeals court said Owen incorrectly instructed the jury when he said jurors did not need to find a nexus between Quattrone's actions and pending investigations of his company.

"We cannot confidently say that if a rational jury was properly instructed, it is clear to us beyond a reasonable doubt that they would have convicted Quattrone," the appeals court wrote in a 61-page ruling.