** Apple AAPL.O shares down 4.5% on Tues after report its long-awaited foldable phone has been encountering setbacks in engineering test phase, which could lead to delays in its mass production and product shipment schedule

** Engineering development issues could delay the first shipments of the foldable iPhones by months in a worst-case scenario, Nikkei Asia reported, citing sources

** Nikkei reported in Jan that AAPL would focus on delivering its first foldable iPhone and two non-folding models with upgraded cameras and larger displays for a flagship launch in the second half of 2026

** AAPL stock on course for biggest one-day pct decline since Feb 12, when it fell 5% amid a broad tech selloff spurred by worries about artificial intelligence disruption

** With move on the session, shares down ~9% YTD vs S&P 500 Tech sector's .SPLRCT ~8.5% decline and Nasdaq's .IXIC ~7% drop