AT&T shares sank 6% before the opening bell, despite quarterly earnings that came in better than expected, while Verizon and T-Mobile are also in the red. The culprit: Elon Musk.

When SpaceX reported earnings yesterday, it reaffirmed plans to expand its Starlink satellite service beyond broadband and into the wireless market, putting it in more direct competition with established telecom companies.

Starlink Mobile, as the business is called, could ultimately generate "several hundred billion dollars in revenue a year," Musk told analysts on the earnings call, hinting at other plans that SpaceX has yet to make public.

The company aims to launch service in early 2028, SpaceX President Gwynne Shotwell said in yesterday's earnings call.