A Miami firm has become the latest to join a wave of litigation against stock trading application Robinhood Financial LLC over the company's decision to restrict trading in certain securities, including shares of GameStop Corp. and Nokia Corp., amid an unprecedented Reddit-fueled price hike.

The Ferraro Law Firm filed the complaint Saturday in the Southern District of Florida, accusing the online brokerage firm of using "sleazy" business practices to betray the customer base it claimed to serve.