A report that the launch of a foldable iPhone could be delayed sent Apple shares down 4 percent on April 8, Nikkei Asia reported on April 7 local time.

Apple is believed to have been unable to resolve engineering issues in developing a foldable iPhone. A person familiar with the matter said, "Apple and its supply chain are working to meet a tight schedule, but the solutions available now are not enough to fully resolve the engineering issues," adding, "More time is needed."

The foldable iPhone had initially been expected to be released in September 2026 alongside the iPhone 18. If the schedule slips, that plan could also change. Apple has unveiled four iPhone models every September at its new product event since 2020.

Nikkei Asia cited April to early May as a key period to settle engineering issues before production. Apple did not respond to a request for comment from CNBC on the matter.

Samsung Electronics, Apple's biggest competitor in the U.S. smartphone market, released its first foldable phone in 2019. The iPhone is a core business for Apple's performance. Apple recorded $143.8 billion in revenue in the first quarter of fiscal 2026, and more than half came from the iPhone.

The delay talk was reported to be unrelated to a shortage of memory chips raised recently amid rising iPhone demand.