Sallie Mae is trading $19.74, down 18.6%, after an investor-focused law firm announced an investigation into potential corporate wrongdoing involving the company and certain executives. - The investigation targets investors who purchased securities before July 25, 2025, and continued holding them, intensifying concerns about corporate disclosures. - The broader market was mixed on September 22, 2026, making company-specific legal news the clearest explanation for the after-hours selloff.