A Practice Note discussing strategies for defending against 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 because the plaintiff failed to plead or prove the loss causation element of its claim. This Note explains the requirements for pleading and proving loss causation in a case based on misrepresentations and omissions, and provides practical strategies for challenging the plaintiff's claims at the motion to dismiss, class certification, and summary judgment stages.