Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Cirrus Logic (NASDAQ:CRUS) have sunk today by as much as 12% following Apple's (NASDAQ:AAPL) earnings results,

So what: Apple has long been Cirrus Logic's largest customer, making the smaller company a favorite Apple component play. Investors were disappointed with iPhone sales and now fear the shortfall will weigh on Cirrus Logic's own results, as it's the exclusive supplier of audio codecs for iOS devices.

Now what: Apple said it sold a total of 75 million iOS devices during the quarter. That total is more relevant to Cirrus Logic than just the iPhone figure, since its codecs are found in all iOS devices. iPad units came in as expected. Cirrus Logic is preparing to report after the close today, so investors are bracing themselves for some possible downside.

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Fool contributor Evan Niu, CFA, owns shares of Apple. The Motley Fool recommends Apple. The Motley Fool owns shares of Apple and Cirrus Logic. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.