The U.S. Federal Trade Commission opened a broad inquiry this week into Apple Inc., Alphabet Inc., Amazon.com Inc., Microsoft Corp. and Facebook Inc.’s acquisitions of smaller companies between Jan. 1, 2010 and Dec. 31, 2019, and whether they have harmed competition.

The new probe comes even as the FTC and the U.S. Department of Justice continue other antitrust investigations of the big tech giants and whether they are restraining competition in online search, social media and retail; and after congressional hearings about whether their market dominance is damaging consumers’ privacy.