After a holiday, you'd think the stock market would return refreshed and ready to move forward. But investors brought in the first trading day of September with a whimper, as falling manufacturing figures in the U.S. reawakened concerns that the economic recovery may not be as strong as many have hoped. Particularly troubling about the Institute for Supply Management's data was that companies hired the fewest workers since November 2009, making it clear that lack of employment opportunities will keep weighing on the labor force for some time. Add in continuing concerns about Europe, and the Dow Jones Industrials (INDEX: ^DJI) got off to a tough start, falling 86 points just after 10:45 a.m. EDT and having briefly dropped below the 13,000 level earlier in the morning.

As you'd expect on any day in which economic news is in the spotlight, economically sensitive stocks were among the biggest fallers. Caterpillar (NYSE: CAT) in particular was hard-hit, falling almost 3% on the drop in manufacturing activity. Caterpillar has been unusual in the extent to which it's betting on the health of the U.S. economy while making forays overseas, so it's not surprising that investors are concerned about its future if the recovery stalls out.

Conversely, stocks that benefit from a slower economy did well. Wal-Mart (NYSE: WMT) gained more than 0.5%, again demonstrating its tendency to thrive in a tough economic environment. As shoppers lose purchasing power, Wal-Mart often ends up being the beneficiary, typically at the expense of higher-end retailers.

Finally, ExxonMobil (NYSE: XOM) and Chevron (NYSE: CVX) both fell more than 0.5%, as oil prices declined by about $1 per barrel. The manufacturing sector is a key proxy for overall economic activity, and with energy use directly correlated with economic growth, signs of a slower economy point to potentially lower future demand.

Look to the long run
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Fool contributor Dan Caplinger doesn't own shares of the companies mentioned. You can follow him on Twitter @DanCaplinger. The Motley Fool owns shares of ExxonMobil. Motley Fool newsletter services have recommended buying shares of Chevron. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Fool has a disclosure policy.