South Korean electronic parts suppliers Samsung Electro-Mechanics Co Ltd, Apple's supplier of multi-layer ceramic capacitors, dropped more than 5 percent, while LG Innotek Co Ltd plunged 9.5 percent.
Apple said earlier this month it would stop giving the number of iPhones, iPads and Mac computers it sold in a quarter, a closely watched metric and a key indicator of the company's success.
TF International Securities analyst Ming-Chi Kuo cut his forecast for iPhone XR shipments from 100 million to 70 million.
While it isn't unusual to hear that Apple is cutting orders for its latest handsets from time to time, investors believe a real crisis is at hand.
Japan's Nikkei reported earlier this month that Apple had told its smartphone assemblers Foxconn and Pegatron to halt plans for additional production lines dedicated to the iPhone XR, the cheapest of this year's new launches.
In a report Monday, Kuo also forecast a year-over-year decline in overall iPhone shipments for the beginning of 2019.
Apple has lost $120 billion in market capitalisation since the last trading day of September, and many analysts are warning that the brief days of Apple being a trillion dollar company are over.
Alibaba Singles' Day tops $30 billion but growth rate plunges
Alibaba's Singles' Day sale apparently is world's biggest sale even bigger than America's Black Friday and Cyber Monday combined. The Jack Ma-led e-tailer registered sales worth 69 billion yuan, or $9.92 billion, within one hour of the November sale event.
Kuo has reduced "his overall iPhone shipment forecasts by 15-20 percent for the first quarter of 2019", notes the report.
The firm hoped the iPhone XR would persuade owners of older iPhones to switch to the newer model, which costs $749 (£749) - a sizable discount from the $999 iPhone XS and the $1099 XS Max.
Apple accounted for half of Lumentum's revenue in its December quarter in 2017, while the iPhone is expected to represent 50 percent of Japan Display's revenue this year, according to the Wall Street Journal.
In a note on Monday, Wells Fargo gave Apple stock a market perform rating and wrote that "investors could consider Lumentum's updated guidance as reflecting as much as a 30% cut in Apple orders", as cited by CNBC.
Adding to Monday's negative news, Longbow Research cautioned that Apple is facing weak iPhone demand in China. In other words, whether or not iPhone XR sales are above or below projections is arguably irrelevant as long as Apple keeps finding ways to boost revenue, which is clearly more important than how any one specific iPhone model is doing in the marketplace.
The move led analysts to question the company's business and its share price has since dropped 12.6%.