"Controlling person liability" claims have become increasingly common in securities litigation. Due to a circuit split in how these claims can be established, plaintiffs have taken advantage of the relatively low threshold required in some jurisdictions to establish a prima facie case of controlling person liability. Asserting such claims in these plaintiff-friendly jurisdictions allows the plaintiff to survive a motion to dismiss with ease and forces the defendant to marshal a defense. As such, alleging controlling person liability has become a favorite tack-on claim in securities-related lawsuits against companies, including the recent high-profile cases involving Tesla and Apple.