T-Mobile stock rose after the wireless services firm said it is not interested in buying a cable TV company.

T-Mobile is using its wireless cash flow to fund a joint-venture-driven move into fiber broadband, while Cable One is accelerating multi-gig upgrades and preparing for a $2-$5 back-book pricing reset.

Less than a decade after cable giants like Comcast and Charter Communications jumped into the mobile business, the segment has become a significant financial driver. Nearly half of all wireless line ...