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 high-tech manufacturing equipment builder Veeco Instruments (Nasdaq: VECO) fell as much as 13% this morning on very heavy volume.

So what: LED specialist Aixtron (Nasdaq: AIXG) just reduced its revenue and margin guidance because of plummeting unit prices and several delayed orders. Veeco makes a market in LED manufacturing equipment; ergo, bad industry news produces an uncomfortably close haircut.

Now what: The entire LED industry stumbled on Aixtron's warning, including an 8% drop for materials provider AXT (Nasdaq: AXTI), a 7% drop at worst for fellow equipment designer CVD Equipment (NYSE: CVV), and of course an 18% plunge for Aixtron itself. The long-term promise of LED lighting remains solid, but investors are quick to sell at the first hint of short-term trouble. Unless you truly believe that Universal Display (Nasdaq: PANL) and its OLED lighting products will kill LED lights entirely -- which is a charming but silly notion -- you're better off treating these knee-jerk panics as buying opportunities. This is exactly the kind of enriching event that watchlists were made for.

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Fool contributor Anders Bylund holds no position in any of the companies discussed here. Motley Fool newsletter services have recommended buying shares of Universal Display. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool is investors writing for investors.