Former Enron boss Jeffrey Skilling has been ordered to go straight to jail, after a judge denied his request to remain free during his appeal.
Skilling was found guilty of fraud, insider trading and conspiracy
Judge Patrick Higginbotham said he had made his decision as the appeal was unlikely to result in the overturning of all Skilling's convictions.
Skilling now has to report to a prison to begin his 24-year sentence.
In May he was found guilty on 19 counts of conspiracy, fraud and insider trading over Enron's collapse.
Judge Higginbotham noted "serious frailties" in Skilling's convictions.
But he said those problems failed to raise a "substantial question" likely to result in the overturning of all Skilling's convictions - the standard required to grant bail during appeal.
Kenneth Lay died at his Colorado ranch in July
The former chief executive of the US energy giant was convicted together with Enron's ex-chairman Kenneth Lay.
Mr Lay has since died following a heart attack in July.
Under Texas law, because his death came before he was able to appeal against the verdict, his conviction has been quashed.
The scandal at the one-time energy giant left 21,000 people out of work, and shook corporate America, when the firm went bankrupt in 2001 with debts of $31.8bn (£18bn).
Skilling was found to have orchestrated a series of loss-making deals and financial schemes to try to hide debts from investors.