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 Chinese diesel engine manufacturer China Yuchai International (NYSE: CYD) were stalling out today, falling as much as 23% in intraday trading on heavier-than-average volume.

So what: I pity the companies that had to announce earnings today. With the broad market going absolutely berserk with selling, even a hint of bad news would be enough to send an individual stock into a tailspin. And it seems China Yuchai's earnings provided just that fuel for bearish traders. For the second quarter, the company's total revenue was flat with last year, while earnings per share fell from $0.74 in 2010 to $0.64. According to Capital IQ, analysts were expecting per-share profit of $0.65 on revenue of $624 million.

Now what: It doesn't seem like investors have much interest in anything right now except selling and selling fast. The U.S. ratings downgrade from Standard & Poor's and the cloudy economic picture for the U.S. may not have a direct impact on China Yuchai, but in the short term investor psychology can be very powerful, and right now it's in bad shape. Investors with China Yuchai on their radar may want to step back and take a sober view of the earnings report and the economic situation in China rather than simply surrendering to the broader market panic.

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