Sprint shares surged after majority owner SoftBank announced a deal to invest $50 billion in the U.S., aiming to create 50,000 jobs.
Donald Trump announced the deal after meeting with SoftBank CEO Masayoshi Son, a Japanese billionaire and technology investor, at Trump Tower in New York.
The stock climbed as much as 6 percent, quickly trading more than twice its 30-day average volume as more than 52.7 million shares changed hands. Sprint shares later pared those gains, ending the session about 1.5 percent higher on the day.
Shares of T-Mobile gained 2 percent in sympathy, also passing its 30-day average volume as more than 7.5 million shares changed hands in afternoon trade. The stock ended the session slightly below those levels, but still gained about 1.8 percent.
In August, Bloomberg reported that Son was still eyeing T-Mobile and would still like to merge it with Sprint. In 2014, the Japanese billionaire considered buying T-Mobile, but dropped the effort once U.S. officials signaled they would be against the potential merger.
Both stocks have done well this year. With Tuesday's gains, T-Mobile shares have gained 43 percent so far, while Sprint shares have rocketed an eye-popping 125 percent.
— CNBC's Jacob Pramuk contributed to this report.