Bernstein analyst Tony Sacconaghi is worried Apple's iPhone sales will drop if Apple can't get the new iPhone 8 to customers during the ever-important holiday season.
"If the phone is materially constrained once we hit the holiday season, post-October 15, then it's worrisome," Sacconaghi said during CNBC's "Fast Money."
Sacconaghi said phones from Apple and other companies are typically hot sellers during the holidays because people have time to find new phones and figure out wireless plans.
"If [the iPhone 8 is] delayed and consumers feel they won't get it until 2018, you run the risk that people will look to other devices," he said.
To play devil's advocate, consumers don't typically flock away from Apple, which often highlights the number of Android switchers it gains each year. Apple's vast ecosystem — including the iPad, Macs and its software products — also makes it hard to simply give up and switch to Android.
Sacconaghi explained that it's common to see a one-to-three-week delay for a new iPhone. He warned that any outside delays, especially orders placed in September or October that might not arrive until 2018, would cause concern.
Apple has reportedly struggled with several issues while building the most high-end new iPhone, which has been referred to as the iPhone 8. The Wall Street Journal said on Thursday that Apple ran into problems trying to embed the fingerprint reader into the display, a feature it eventually ditched, and that Apple is constrained by the number of new OLED panels it's buying from Samsung.
Apple is expected to announce the iPhone 8 alongside two other iterative iPhone updates, possibly named the iPhone 7s and iPhone 7s Plus, during a press event on Sept. 12.
CNBC reached out to Apple for comment but a spokesperson was not immediately available.