Yes, an investor can sue for a securities violation under rules such as SEC Rule 10b-5. This federal rule allows a private party to bring a lawsuit against a person or entity that engaged in fraud, deception, misrepresentations, or other violations in connection with the purchase or sale of a security. State securities laws, sometimes known as Blue Sky laws, also may provide a private right of action for securities violations. Some of these laws may be more favorable to investors than federal laws.