A Tyler, Texas, company was riding high last year after scoring a $533 million jury verdict against Apple Inc. for infringing its patents on online payment technology. It was one of the largest verdicts ever won by a nonpracticing entity and prompted a massive counterattack by Apple and fellow targets Samsung Electronics Co. and Google Inc.

Since then, U.S. District Judge Rodney Gilstrap has set aside Smartflash LLC’s damages award, and the Patent Trial and Appeal Board (PTAB) has cast doubt on the patents. On Wednesday, the U.S. Court of Appeals for the Federal Circuit sounded poised to strike a death blow.