Comcast Corp., the nation's No. 1 cable-TV company, is talking with Sprint Corp. about access to its wireless network as speculation boils that Sprint could be bought out by a coalition of cable companies or by T-Mobile.

Sprint is considered the weakest of the four national wireless carriers and has been the persistent target of takeover rumors.

Just this month, Comcast launched its own smartphone service, branded Xfinity Mobile, by reselling Verizon Communication Inc.'s wireless network with Comcast phones and utilizing its 17 million WiFi hotspots.

Comcast also has a reseller agreement with Sprint dating to 2008, when it invested with Time Warner Cable and computer-chip company Intel in Clearwire, a failed high-speed wireless venture. Comcast and Charter Communications, which acquired Time Warner Cable in 2016, are now looking to improve the financial terms of that reseller agreement to operate cable-based wireless services, a person familiar with the talks said.

But some Wall Street and telecom industry observers speculated Tuesday that the Comcast-Sprint talks could advance to include an equity stake or purchase of Sprint.

"Comcast and Charter have taken their partnership to the next level with an exclusive re-seller agreement with Sprint, likely halting any potential T-Mobile-Sprint deal in the near-term. One scenario could entail either [Comcast or Charter] taking a stake in or merging with Sprint," Amy Yong, telecom analyst with Macquarie Capital, said Tuesday morning.

Comcast had no comment on Tuesday. Charter could not be immediately reached for comment.

Earlier this year, Comcast and Charter agreed each would not acquire a wireless carrier such as Sprint without seeking the approval of the other, a deal that could enable the two cable companies to jointly negotiate terms with smartphone manufacturers.

Sprint stock spiked on the news Tuesday, jumping 2 percent, or 18 cents, on a down day on Wall Street to close at $8.18. Comcast shares fell 34 cents, or 0.86 percent, to $39.25.

Sprint chairman Masayoshi Son and the cable companies have entered into a two-month exclusive agreement for discussions through late July, the Wall Street Journal reported. An agreement would put a speculated deal between Sprint and T-Mobile on hold.

Son, Japan's richest man with an estimated wealth of $23 billion, founded and runs mobile telecom and investment firm SoftBank. In 2013, SoftBank acquired control of Sprint for about $22 billion. Though the company owns valuable wireless spectrum, it also has been troubled with an aging network and, now, discounting among the four competing wireless carriers.

Brian Roberts, Comcast's boss, was speaking Monday night at the Aspen Institute's "Ideas Festival" in Colorado when news broke online of talks between cable companies and Sprint.