Shares in Zurich-listed AMS (AMSSY)   plunged as much as 24% on Tuesday after the semiconductor maker said it expects earnings to weaken in the fourth quarter due to a production glitch as well as a "negative development" at a specific customer in the consumer market.

AMS makes analog semiconductors used in sensors for consumer electronic products as well as automotive, industrial and medical products.

Shares in AMS were recently down 17% in Zurich to Sfr25.00. The supplier to Apple (AAPL) - Get Report reported third-quarter results after the markets closed on Monday. Apple is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio.

The Premstatten, Austria-based company said it expects fourth-quarter revenue of between €127 million ($138 million) and €134 million, down from €146.7 million in the third quarter. It also predicted an operating margin of 11% to 13% for the quarter, down from 19% in the third quarter.

"For the fourth quarter 2016, we see a muted development of our business in revenues and earnings, particularly due to a negative development at a specific customer in the consumer end market and a production yield issue in an industrial product line," the company said, adding that it does not expect the production glitch to be resolved before early next year.

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The company also attributed the likely decline in revenue to product maturity, weakening product mix, and subdued demand in non-consumer markets.  AMS added that the negative development at the mystery customer could hurt its inventory.

For the third quarter, AMS booked diluted earnings per share of €0.81 on revenue of €146.7 million and net profit of €55.9 million. That compares with EPS of €0.47 on revenue of €153.0 million and net profit of €34.0 million booked in the same period a year earlier.

On Monday, AMS also announced it had agreed to buy Heptagon, an optical packaging and micro-optics firm, for $634 million from an undisclosed seller. The group said it will pay $64 million in cash, and shares worth  $570 million, including treasury stock and new shares equivalent to 15% of its current equity capital.

AMS expects Heptagon to boost its revenue from the middle of next year.

Following the combination with Heptagon, AMS expects a compound annual growth of 30% for the next three years and an Ebit margin of 30% from 2019. The firm expects the acquisition to boost its presence in the smartphone and mobile device business.

Apple is scheduled to report fourth-quarter earnings results Tuesday.