AST SpaceMobile stock has had a few stressful days -- all because of SpaceX. Tuesday won't be any easier.

In premarket trading, shares of the space-based communications company fell 4.6% at $49.10 after catching a downgrade.

Piper Sandler cut its rating to Hold from Buy and dropped its price target dropped to $54 from $98 -- about 45%.

Piper is worried about SpaceX's mobile communications ambitions and SpaceX's ability to hurt AST's competitive satellite communications network by reducing launch capacity for competing services, according to ratings aggregators summarizing the research.

Piper Sandler didn't immediately respond to a request for the downgrade report.

There is good reason for concern. SpaceX sent a shockwave through the wireless industry this past week after buying low-band spectrum -- essentially the pipes that carry wireless data -- that moves SpaceX closer to offering full mobile wireless services.

SpaceX's wireless ambitions are no secret. Still, shares of AT&T, Verizon Communications, and T-Mobile fell between 8% and 14% on Friday. AST stock dropped more than 10%.

The severe stock reactions actually led to an AST stock upgrade. On Monday, Deutsche Bank analyst Bryan Kraft upgraded shares to Buy from Hold, noting that shares were down 65% from all-time highs and that traditional wireless carriers need AST to compete against SpaceX.

SpaceX's mobile ambitions could be a good thing for AST. Or maybe not.

To be sure, SpaceX has never restricted launch capacity. It launches AI satellites for Alphabet and communications satellites for Amazon.com. What's more, AST can use other launch providers, including Jeff Bezos' Blue Origin.

That doesn't help AST shares on Tuesday, though. The stock is in for another tough day, with investors battered by uncertainty.

Overall, 38% of analysts covering AST stock rate shares Buy, according to FactSet. The average Buy-rating ratio for S&P 500 stocks typically ranges from 55% to 60%. The average analyst price target for AST stock is about $79.