Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

For the first time in a long time, the Dow Jones Industrials (DJINDICES:^DJI) has been struggling to maintain traction over the past several days. After going more than two years without a true Dow correction, investors appear to be looking at the stock market with a glass-half-empty mentality. That will put extra pressure on DuPont (NYSE:DD) and Pfizer (NYSE:PFE) to deliver earnings results tomorrow that will allay fears about a pullback in U.S. economic growth.

In the past, DuPont has issued its press release with highlights of earnings results as early as 6 a.m. EST. A conference call is scheduled for 9 a.m. EST. Pfizer has scheduled its own 10 a.m. EST conference call, following a release that will likely come close to 7 a.m. EST.

For DuPont earnings, investors will pay the most attention to the company's ongoing plans to spin off its performance-chemicals unit from its faster-growing agricultural division. In recent quarters, the disparity in how the two units have fared has been striking, with low-margin commodity chemicals seeing extensive revenue and earnings pressure even as demand for agricultural products remains strong. Dismissing its nonagricultural businesses entirely would mean giving up on promising areas like photovoltaic solar materials, but DuPont appears more likely to continue using a surgical approach toward carving out the businesses it feels have the least potential for profitability and growth. Given high expectations for DuPont earnings growth, any shortfall in net income could give the Dow even more reason to fall. As one of the smaller blue-chip components by market capitalization, DuPont also needs to be careful about making itself so small that it invites eviction from its spot in the Dow 30.

Meanwhile, the Pfizer earnings report could also bring news on the restructuring front, as investors wonder whether the company will make further moves even after spinning off its animal-health unit. In particular, the possibility of separating Pfizer's generic-drug production division from its branded proprietary drug business could make investors more excited about the stock. Pfizer will likely see another big drop in revenue from this quarter, so shareholders aren't expecting perfection from the company. Yet amid huge competition in the pharmaceutical space, Pfizer still needs to demonstrate its ability to keep earnings up and bolster its pipeline to produces long-term growth.

At this point, it's unclear whether good news from Pfizer and DuPont would be enough to stop the Dow's recent drop. Disappointments, though, could be disastrous given the current mood among investors, and so you should be sure to watch DuPont and Pfizer when they release their earnings reports tomorrow morning.

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Fool contributor Dan Caplinger has no position in any stocks mentioned. You can follow him on Twitter @DanCaplinger. The Motley Fool has no position in any of the stocks mentioned. 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 Motley Fool has a disclosure policy.

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