The case of Imagination Technologies Group Plc. (IMG.L) is a study on the perils of being a supplier to Apple Inc. (AAPL). The Hertfordshire, U.K.-based semiconductor firm is up for sale after Apple announced in April that it would no longer use chips designed by the company. Imagination reportedly derived approximately 40% of its overall revenue from the iPhone manufacturer. (See also: Apple Imagines Away Chip Supplier's Future.)

By virtue of its operational scale and sales, the Cupertino, California-based giant wields enormous clout among its suppliers. The big ones, such as Samsung Electronics Co. Ltd. (SSNLF), have a diversified portfolio of clients that enables them to weather downturns in their relationship with Apple. But the medium- and small-sized businesses that derive a majority of their business from Apple are at its mercy. (See also: 10 Major Companies Tied to the Apple Supply Chain.)

Here are two companies that are dependent on Apple for most of their profit and revenue.

Flexium Interconnect, Inc. (6269.TW)

Flexium Interconnect is a Taiwan-based company that designs and manufactures flexible printed circuit boards. The company is expected to win big in Apple's shift toward flexible OLED screens for its iPhone. That might be welcome news for its investors as well, since Flexium mostly reported flat revenues last year. The company reported a 76.1% decline in revenues on a quarterly basis earlier this year. While Flexium attributed the decline to foreign exchange transaction losses, a Digitimes report quotes anonymous sources as saying that the decline was due to weak iPhone 7 demand. That is not surprising, since Flexium is reported to derive between 60% and 70% of its total revenue from Apple. (See also: 3 Chipmakers That Are Tied to Apple's iPhone.)

Cirrus Logic, Inc. (CRUS)

Cirrus Logic is a provider of audio circuits. The Austin, Texas-based company generated 85% of its $1.2 billion in revenue from Apple as of this February. The company has reported annual revenue growth figures of more than 25% for the past three years. In its earnings calls, Cirrus Logic simply refers to Apple as "our largest customer" and refuses to divulge much information about its relationship with the company. Cirrus Logic has begun to diversify its client base in recent times and is said to be working with makers of Android handsets to incorporate its technology into their products. For the next year, the company has forecast a moderating single-digit growth range. (See also: Cirrus Logic Waves Red Flag for Apple Ecosystem.)

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