https://www.cnet.com/news/senate-democrats-urge-regulators-to-put-kibosh-on-t-mobile-sprint-merger/

If approved, the merger, announced last April, would reduce the number of national wireless carriers in the US from four to three. In 2011, the FCC and Justice Department rejected AT&T's acquisition of T-Mobile, saying the reduction in competition would harm consumers. The senators echoed the sentiment in their letter on Tuesday.

"Antitrust regulators around the world have consistently blocked four-to-three mergers in the mobile and telecommunications industry, and those who have allowed such mergers have lived to regret it," they wrote.