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 ON Semiconductor (Nasdaq: ONNN) fell as much as 10% after analysts at UBS downgraded the stock, along with Microchip Technology (Nasdaq: MCHP) and Maxim Integrated Products (Nasdaq: MXIM).

So what: All three stocks saw their ratings cut due to concerns over spending trends in the auto, PC, and consumer electronics markets, Forbes reports. ON, in particular, was cut from buy to neutral as UBS shaved its target price from $15 to $11 a share.

Now what: Should investors be concerned? Maybe, but with the sell-off the stocks now trades for a sharp discount to its long-term projected earnings growth rate, resulting in a 0.61 PEG ratio. My guess is whatever legit pessimism that exists has already been priced in. Do you agree? Disagree? Weigh in using the comments box below.

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Fool contributor Tim Beyers is a member of the Motley Fool Rule Breakers stock-picking team. He didn't own shares in any of the companies mentioned in this article at the time of publication. Check out Tim's portfolio holdings and Foolish writings, or connect with him on Google+ or Twitter, where he goes by @milehighfool. You can also get his insights delivered directly to your RSS reader.

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