Sprint, the nation's fourth-largest wireless network, is pursuing a merger with the cable company Charter Communications, according to a report by the Wall Street Journal.

The potential tie-up could create a new firm that would be controlled by Sprint Chairman Masayoshi Son and his Japanese megacompany, SoftBank, the Journal said. At a time when the cable and wireless industries are undergoing enormous changes, a deal between the companies could mean even more disruption — as well as a more complicated relationship involving Comcast.

Charter and Comcast had jointly agreed this spring not to start merger or acquisition talks with another wireless company for at least a year without each other's participation or go-ahead. The cable industry has been seeking a way to enter the wireless business for years; as Americans increasingly shift their Internet consumption to mobile devices and take their data usage to go, traditional cellular carriers such as AT&T and Verizon have stood to benefit massively at the expense of home Internet providers such as Comcast and Charter.

The cable industry has fought back with public WiFi hotspots that allow, for example, Comcast's Xfinity customers to access mobile broadband without being physically at home. But a truly widespread and robust wireless solution that can compete with cellphone carriers has been elusive, prompting analyst speculation about when and how companies such as Charter would launch a true cellular service.

The agreement between Comcast and Charter helped dampen analyst expectations that either company was imminently planning a major leap into wireless.

Both companies are tinkering with it in a limited manner; Comcast, for example, has begun offering wireless service through a program known as Xfinity Mobile, which uses Verizon's cellular network when Comcast's own WiFi is out of range.

But on an earnings call this week, Comcast chief executive Brian Roberts said the company is still content with its current strategy, hinting that no major deals were about to drop.

“I don't see something happening in that we envy a position we don't have today,” he told investors.

With a Sprint-Charter deal looming, Comcast could play kingmaker by exercising its contractual ability to bless or bury any such merger — even before any regulators get involved.

Sprint this year had also reportedly been courting T-Mobile about an acquisition, and Son could try to pursue both deals simultaneously, according to the Journal.

For the SoftBank-owned carrier, the deal with Charter suggests Son is increasingly desperate to find a deal that could rescue the flagging company, which has suffered deep subscriber losses and poor financial performance. Analysts have blamed a weak network and the company's seeming inability to upgrade it.

News of the potential deal appeared to lift investors' hopes; shares of Sprint surged by nearly 6 percent in after-hours trading Friday.