A Practice Note focusing on timeliness issues for civil securities fraud claims brought by private plaintiffs under Section 10(b) of the Securities Exchange Act of 1934 and Securities and Exchange Commission Rule 10b-5. This Note discusses the applicable statute of limitations and repose, including the legal framework for class action tolling under American Pipe & Construction Co. v. Utah, and provides strategies for asserting timeliness defenses. It also discusses special rules that apply to actions by government entities subject to an extender statute.