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 energy industry supplier Power Integrations Inc (NASDAQ:POWI) dropped as much as 35% today after reporting earnings.

So what: Revenue rose 8% from a year ago to $83.1 million, and non-GAAP earnings jumped 19% to $0.56 per share. The problem is that revenue growth fell short of estimates, and earnings per share were $0.03 short as well.  

Now what: This is a huge sell-off for an earnings miss, particularly one that only missed by a few pennies. Management also said it expected sequential revenue growth next quarter as growth applications pick up. It looks like the sell-off was way overdone, and with shares trading at just 17 times this year's estimates, I think there's upside even after this earnings miss.