Merger Rules Get Tougher in Crackdown by Antitrust Enforcers (2)

US antitrust agencies stepped up the Biden administration’s crackdown on mergers and acquisitions with a sweeping overhaul of rules the government uses to determine whether deals violate competition law.

The changes come on the heels of several bruising defeats for the government in blocking vertical mergers. Last week, the Federal Trade Commission lost a legal fight over Microsoft Corp.’s $69 billion deal to buy Activision Blizzard Inc. It was the third big failure for antitrust enforcers, after the Justice Department’s unsuccessful bids to block UnitedHealth Group Inc. from buying up Change Healthcare Inc. last year and AT&T Inc.’s ...