Nacchio was convicted in 2007 in connection with the sale of more than US$100 million of Qwest stock in 2001. He was sentenced to six years in prison and fines of $19 million, and ordered to repay $52 million from stock trades. Nacchio's legal team challenged the conviction, arguing in part that the trial judge in the U.S. District Court for the District of Colorado should have allowed expert testimony from a law professor about Nacchio's stock-trading patterns.

A three-judge panel of the U.S. Court of Appeals for the Tenth Circuit last year reversed Nacchio's conviction and granted him a new trial. His sentence was stayed and he was released pending the appeal. But the full court of nine judges re-examined the expert testimony issue.

On Wednesday, in a 5-4 decision, it ruled that the testimony was excluded properly. In addition to reinstating Nacchio's conviction, it revoked his release from prison and the stay of his sentence. The full court then sent the case back to the three judges for decisions about sentence enhancement and forfeiture of assets.

Because it revoked the stay of Nacchio's sentence and his release pending appeal, it appeared Nacchio may be imprisoned soon.

Nacchio led Qwest, a regional telecommunications carrier, from 1997 to 2002. Nacchio was accused of selling his own stock while publicly forecasting strong growth at the company even though he knew there were problems. He was convicted of 19 counts of insider trading.