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 solar-module manufacturer JinkoSolar (NYSE: JKS) weren't looking too sunny today as investors knocked shares down as much as 10% in intraday trading.

So what: JinkoSolar investors can go ahead and scowl in the general direction of LDK Solar (NYSE: LDK), since the weak guidance issued by the latter company seems to be pulling down the entire sector today. As my fellow Fool Travis Hoium discussed, a more-profitable-than-expected first quarter at LDK was overshadowed by the fact that the company's second-quarter revenue forecast was lower than what analysts were looking for.

Now what: After a torrid love affair with solar companies a few years back, investors have shifted their amore elsewhere. While the unpredictability of the industry as a whole doesn't entice me, I can’t blame investors that are attracted to the pinch-yourself-to-see-if-it's-real valuations that many of these stocks carry.

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Fool contributor Matt Koppenheffer does not have a financial interest in any of the companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or Facebook. The Fool’s disclosure policy prefers dividends over a sharp stick in the eye.