JPMorgan Chase & Co. was ordered by a Dallas jury to pay more than $US4 billion ($A5.1 billion) in damages for mishandling the estate of a former American Airlines executive, although experts predict the verdict will probably be knocked down on appeal.

Jo Hopper and two stepchildren won the probate court verdict over claims that JPMorgan mismanaged the administration of the estate of Max Hopper, who was described as an airline technology innovator in a statement issued by the family's law firm.

A 6500-strong putter collection was one of the assets held by JPMorgan.

Large punitive damages verdicts like the one in the Hopper case are often scaled back because the U.S. Supreme Court has ruled they can't be disproportionate to actual damages. In this case, the jury awarded less than $US5 million in actual damages.

The bank said it acted in a professional manner and in good faith on Hopper's estate and is "highly confident" the jury verdict won't stand under Texas law.