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 Power Integrations (Nasdaq: POWI) jumped as much as 20% today after the company released first-quarter earnings.

So what: Revenue grew 8% sequentially to $71.8 million. Net income was $7.5 million, or $0.36 per share. Analysts had only expected revenue of $67.3 million and earnings per share of $0.27.

Now what: Industrial and consumer applications drove the growth in the first quarter, but high-voltage applications could drive future growth. The company just completed its acquisition of CT-Concept, giving the company exposure to high-voltage power conversion applications, including the fast-growing renewable-energy industry. Growth is impressive, but I'm cautious about today's bounce because the market has a lot of growth already priced in, with shares trading at 20 times forward earnings estimates.

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