A Practice Note providing guidance for counsel to evaluate a private plaintiff's standing to assert claims based on material misstatements or omissions in violation of Section 10(b) and Rule 10b-5 of the Securities Exchange Act of 1934. This Note addresses the constitutional requirements under Article III and the judiciary's prudential principles, as well as the purchaser-seller standing requirement under Blue Chips Stamps v. Manor Drug Stores, 421 U.S. 723, 731-32 (1975). It discusses assignments and investment advisor claims, the forced seller doctrine, actions for injunctive relief, shareholder derivative actions, and class action lawsuits.