Shares of AT&T, Verizon and T-Mobile remained under pressure after SpaceX confirmed its deal to acquire a nationwide 800 MHz spectrum portfolio from Grain Management. The deal is reportedly valued at around $8 billion and would support Elon Musk’s plans to use Starlink for direct-to-mobile service.

The news broke late last week and was followed by the carriers’ worst single-day stock declines in years on October 9th. Weekend analysis suggested that building a competitive network will take time and substantial capital, but the low-band spectrum acquisition makes SpaceX’s mobile ambitions more credible.

Investors are weighing the prospect of greater competition, which could pressure customer pricing and growth at established carriers.