The FTC has just announced an antitrust investigation into Apple, Amazon, Facebook, Google (as well as parent company Alphabet) and Microsoft. The consumer protection agency is requiring that all companies provide information about past acquisitions they've made but "not reported to the antitrust agencies under the Hart-Scott-Rodino (HSR) Act."
The HSR act is a set of amendments made to US antitrust laws in 1976 that requires companies to not complete mergers and acquisitions without making detailed filings with the FTC and Department of Justice; both agencies must determine that those moves aren't anti-competitive. But not all mergers or acquisitions are subject to the HSR Act, so the FTC is essentially asking these companies to open their books on all such transactions. Today's announcement calls for the companies to provide the FTC with details on all transactions completed between January 1st, 2010 and December 31st, 2019.