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 DexCom (Nasdaq: DXCM) have gotten crushed today, down 25%, after the company reported quarterly earnings last night.

So what: The medical device company brought in revenue of $18.3 million, which resulted in a net loss of $0.20 per share. Both figures were below the consensus estimates of $19 million in sales and a net loss of $0.16 per share.

Now what: The gloomy figures triggered a number of analyst downgrades, such as SunTrust Robinson Humphrey, who downgraded the stock from "neutral" to "reduce," and Morgan Keegan, who downgraded it from "outperform" to "market perform." In contrast, Canaccord Genuity is keeping its "buy" rating while adjusting its estimates, but believes DexCom is still well positioned. Expectations aside, the company is still growing top-line revenue at an admirable pace, 56% over last year.

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