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 human-resource software specialist Kenexa (Nasdaq: KNXA) resigned themselves to a 13% overnight plunge on rather average trading volume.

So what: Another month, another weak American unemployment report, and Kenexa lives and dies with the job market. Only a couple of weeks ago, shares jumped 25% on a hopeful earnings report but August has been brutal to this stock.

Now what: As recently as May, I thought Kenexa looked smart for raising expansion capital "while the iron is hot." That glowing-hot hunk of metal has gone stone-cold since then. The job market can't stay dead forever, but Kenexa shareholders will suffer until America starts hiring again.

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