What could have been a far worse day for the markets turned out to be not so bad. Although news of a Socialist victory in France weighed on world markets early, the economically sensitive banking sector didn't seem to blink in the face of Europe's uncertainty. And although the Dow Jones Industrials (INDEX: ^DJI) ended the day down 23 points to 13,016, the S&P 500 (INDEX: ^GSPC) and Nasdaq Composite were both up on the day.

Still, some Dow stocks didn't quite have the same resiliency as the market. Let's look at the Dow's three worst performers for the day.

Hewlett-Packard (NYSE: HPQ), down 1.7%
As earnings season starts to wind down, HP shareholders have a while to wait before they'll get the latest word on how the company's doing. At least based on today's action, though, investors seem to be selling first and asking questions later.

Right now, expectations are for HP's earnings per share to drop by more than 25%, which would mark the third straight quarter of declining EPS. Although shareholders have to be somewhat patient with CEO Meg Whitman's turnaround strategy, they won't wait forever. HP needs to execute on its plan to emphasize higher-margin businesses before the stock drops much further, or else the company could lose investor confidence entirely.

Caterpillar (NYSE: CAT), down 1.3%
Caterpillar didn't get off to a good start after a terrible drop last week. Having fallen almost 6% in the past five trading sessions, Caterpillar just kept falling today.

Yet optimistic investors are taking the drop in Caterpillar as a buying opportunity. With a huge surge in sales in the first quarter and strength even in sluggish areas like the U.S. and Europe, fears about slowing economies in emerging markets may well be overblown. Unless you think long-term growth in construction and mining will slow markedly, Caterpillar should perform well with a competitive position in its industry.

Home Depot (NYSE: HD), down 1.1%
It's hard to take today's decline in Home Depot shares very seriously. Even down 1%, the stock has risen 75% from its August lows and is only a few percent below multiyear highs.

Home Depot reports earnings next week, and already, investors are expecting more from the home-improvement retailer. With quarterly EPS estimates up almost 7% in the last three months, nearly 30% year-over-year earnings growth appears to be within reach. As long as the company can sustain growth rates like that, Home Depot shouldn't have any problem justifying its valuation.

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