T-Mobile US Inc. (NASDAQ: TMUS) experienced its worst trading day since 2013 on Friday, with shares falling 13% to $149 at midday. This decline marks the steepest one-day drop for the company since it began trading under the T-Mobile name in May 2013.

The stock selloff followed a reported deal by Space Exploration Technologies Corp. (NASDAQ: SPCX). SpaceX agreed to purchase nationwide 800 megahertz spectrum licenses from Grain Management. The company plans to utilize these low-band airwaves to pair with its Starlink satellites.

Analysts suggest that this move could position SpaceX as a new competitor to wireless carriers. The deal is contingent upon approval from the Federal Communications Commission.

The market reaction was widespread. Peers AT&T Inc. (NYSE: T) and Verizon Inc. (NYSE: VZ) also saw significant declines, falling 11% and 10%, respectively.