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 water-handling equipment manufacturer Mueller Water Products (NYSE: MWA) jumped as much as 18% in per-market and early trading, but sank back down to last night's closing prices in short order on heavy volume.

So what: Move along, nothing to see here -- Mueller has no significant news going on and the water-equipment sector is pretty quiet in general. China Valves Technology (Nasdaq: CVVT) and Sun Hydraulics (Nasdaq: SNHY) followed similar chart patterns to a modest 2.6% and somewhat more alarming 4.6% drop, respectively, despite the only news between the two being a thumbs-up inspection of a new China Valves product.

Now what: I think we're looking at an amplified version of the larger market today as the Dow and S&P 500 jumped due to good jobs data, but then dropped back down on other economic fears. Water-related infrastructure projects live and die by government projects and housing markets. As for that sudden 18% jump, I don't think you'll find a rational explanation anywhere -- thinly traded stocks like Mueller simply misbehave sometimes.

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