U.S. Bankruptcy Judge Sean Lane said in a short statement that the reasons for the denial were listed in a 32-page opinion dated Nov. 27.
"For those same reasons, the plaintiffs' motion seeking a stay pending appeal is denied," Lane wrote.
The motion was filed by attorney Joseph Alioto on behalf of 40 clients, the Dallas Morning News reported Thursday.
Alioto argued that a delay would do no harm, but the merger would create "irreparable damage" to his clients.
At a Nov. 27 hearing, the airlines disagreed, stating a delay in the merger would be irreparably harmful to them.
Barring any unforeseen surprises, there will be a new airline by Monday morning called American Airlines Group.
The merged company is expected to be listed on the Nasdaq exchange Monday morning, the News said.