Elon Musk’s $44 billion acquisition of Twitter is a step closer to completion as the regulatory waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 officially expired on Friday. The HSR requires companies to give advance notice of transactions above a certain threshold to the Federal Trade Commission and Department of Justice. The agencies have 30 days from the notification to pursue an initial investigation of the transaction to determine whether additional information is needed to assess its legality.  Neither agency requested additional information.