Sprint-T-Mobile ($26 Billion, 2020)

The $26 billion Sprint-T-Mobile merger reduced the number of major US wireless carriers from four to three, sparking years of antitrust opposition from state attorneys general. Critics predicted consumer prices would rise, and by 2023, wireless bills had increased 18% on average—a 2.5x faster rise than the preceding five years. While the deal closed in 2020, its impact remains more measurable than the Microsoft-Activision merger's speculative market concerns, as price hikes directly affected 300 million American subscribers.