Report: SoftBank killing Sprint merger with T-Mobile

SoftBank CEO Masayoshi Son

Sprint and T-Mobile shares fell Monday, on a Japanese media report that SoftBank is prepared to pull the plug on a proposed merger between the two carriers. Per the Nikkei news service:

"SoftBank Group plans to break off negotiations on a merger between subsidiary Sprint and T-Mobile US amid a failure to agree on ownership of the combined entity."

Why it matters: Combining Sprint and T-Mobile would radically transform the U.S. wireless market, creating a more formidable adversary for Verizon and AT&T but reducing the number of overall competitors.