underperformer

noun

1. One who or that which underperforms, having performance that is below average or below expectations; often specifically a company or stock

   “"Any underperformer in this business is vulnerable as a takeover," Raiff said.”

   “Notable among them was the 41½-mile Manchester Piccadilly-Sheffield Victoria passenger service via Woodhead Tunnel (closed on January 5 1970). A financial underperformer since 1,500V DC electrification 16 years earlier, it was a line noted for its spectacular scenery but also for generating little revenue from intermediate stations.”