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 aerospace and defense supplier AAR Corp. (NYSE: AIR) have crash landed today, with shares down by 11% at the low, after the company reported earnings yesterday.

So what: Third-quarter revenue added up to $534.2 million, leading to earnings per share of $0.50, with both figures beating what the market was expecting. The company said the results were "unfavorably affected by aircraft shortages" in its airlift operation within the government and defense services segment, largely due to unscheduled maintenance inspections.

Now what: The aviation supply chain segment was helped by investments that AAR made earlier in the year, while its structures and systems segment put up strong sales growth. CEO David Storch said, "While performance at our airlift operation did not meet our expectations, demand remains strong and we are taking tangible steps to address ongoing aircraft shortages." Storch added that AAR has started focusing more heavily on its precision machining business.

Interested in more info on AAR Corp.? Add it to your watchlist by clicking here.

Fool contributor Evan Niu holds no position in any company mentioned. Click here to see his holdings and a short bio. The Motley Fool has a disclosure policy. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. Try any of our Foolish newsletter services free for 30 days.