A Practice Note discussing when acquired parties are liable for violations of the Hart-Scott-Rodino (HSR) Act. This Note analyzes the antitrust agencies' enforcement actions against acquired parties under the HSR Act, including for gun-jumping violations. It also discusses enforcement actions brought against acquired parties for violating Rule 801.90 by restructuring a deal to avoid or delay an HSR filing and for other failures to file HSR forms. It also discusses the remedies imposed in HSR enforcement actions brought against acquired parties and provides practical tips for counsel representing acquired parties to help prevent liability under the HSR Act.