Oorvo, Cirrus Logic, Lumentum and AMS had all slashed their revenue forecasts for the most recent quarter late last year.

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For the past two months Apple’s suppliers — the firms that make the parts inside iPhones — have issued sales warnings that have eroded the companies’ shares.

On Thursday, it was Apple’s turn. Late Wednesday it reduced its revenue forecast for its most recent quarter because of a significant slowdown in iPhone sales in China.

Apple’s stock fell 10 percent Thursday, putting it on pace for its worst one-day slide in six years. But the warning also rippled across its many suppliers.

Chipmakers Micron Technology and Advanced Micro Devices fell 5 percent and 9 percent. Qorvo, a maker of radio frequency chips, dropped 10 percent, while Cirrus Logic, which supplies audio chips for the iPhone, dropped 8 percent

Lumentum, which supplies optical components for the iPhone, fell 8 percent. AMS, a maker of light sensors for smartphones, tumbled more than 20 percent.

Since introducing the iPhone in 2007, the market for mobile phones has become saturated. Even before Apple’s warning — its first in 16 years — investors had started to grow worried about the company’s ability to sell more phones.

That is partly because Qorvo, Cirrus Logic, Lumentum and AMS had all already cut their revenue forecasts for the most recent quarter late last year. Though none of the companies mentioned Apple, the tech giant is the largest customer for each.

Those announcements weighed heavily on Apple’s stock. Over a three-day period in mid-November, Apple’s stock fell 9 percent following the warnings of Qorvo, Lumentum and AMS.


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