NEW YORK — Shares of Sprint and T-Mobile have tumbled as several news reports cast doubt on a long-expected deal between the two wireless carriers.

The Nikkei Asian Review kicked off by reporting from Japan that Sprint’s owner, Japan’s SoftBank, plans to break off deal negotiations with T-Mobile’s parent company, Germany’s Deutsche Telekom, over disagreements about who would control the combined company.

The Wall Street Journal reported later Monday that SoftBank is “abandoning” deal efforts . Bloomberg reported that deal talks have “hit a serious snag.”

The stories relied on information from unidentified people. Sprint, T-Mobile and SoftBank did not respond to questions from The Associated Press.

Sprint’s stock slumped 9.3 percent Monday. T-Mobile shares dropped 5.4 percent.

U.S. regulators’ concerns thwarted the companies’ previous deal effort in 2014.