A Practice Note providing an overview of the reporting requirements that apply to certain mergers and acquisitions under the Hart-Scott-Rodino (HSR) Act. This Practice Note discusses the types of transactions that require notification, the filing requirements, including the thresholds that apply, and the procedures after filing with the US federal antitrust agencies, such as where a Request for Additional Information and Documentary Material (Second Request) is issued or where the parties engage in a pull and refile strategy to avoid its issuance.