Sprint surged 19.6% to US$6.14 and was halted twice in the 20 minutes following the Wall Street Journal report when it jumped to nearly 25%.
Shares of T-Mobile were up 6.1% to US$63.38 and nearly 7% immediately following the report.
It's the latest saga in a long-running merger attempt for the two companies. They ended talks in November, saying they couldn't reach a deal.
“The latest discussions come just five months after a previous courtship collapsed largely over who would control the combined firm,” reported the Wall Street Journal. “The talks also come in the midst of an antitrust fight between the U.S. government and AT&T Inc,” the newspaper added.
Talks have been knotty in the past, compounded by tensions between German company Deutsche Telekom AG (ETR:DTE), which owns 63% of T-Mobile, and Japanese investment conglomerate SoftBank Group Corp. (TYO: 9984), which holds 85% of Sprint.
T-Mobile and Sprint are Amaerica's third- and fourth-largest wireless carriers, respectively, but lag significantly behind industry leaders AT&T Inc. (NYSE:T) and Verizon Communications Inc. (NYSE:VZ).
A marriage would lend each company the scale necessary to compete. A potential combined behemoth, would boast nearly 100 million customers, putting it ahead of AT&T, which had 93 million U.S. subscribers at the end of 2017, and behind Verizon which ended the year with 116 million subscribers.