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.

The Dow Jones Industrial Average (DJINDICES:^DJI) has moved less than a point at midday as investors debate whether stocks could push higher from levels at or near all-time highs. A large slate of economic data this week could help answer that question, but earnings season is also continuing, with Pfizer (NYSE:PFE) rounding out the Dow's pharmaceutical contingent in reporting earnings tomorrow. Given mixed results from Johnson & Johnson (NYSE:JNJ) and Merck (NYSE:MRK), investors will look for signs of whether Pfizer can outperform its rivals.

Pfizer will release its results before the market opens tomorrow, with last quarter's press release having been made available before 4 a.m. EDT. It will follow up its release with a conference call scheduled to begin at 10 a.m. EDT.

Investors expect Pfizer to post modest gains in earnings from the year-ago quarter, even though Pfizer will likely suffer revenue declines even worse than those Merck reported earlier today. Patent-cliff issues have hurt players throughout the industry, but Pfizer has an advantage over Merck and Johnson & Johnson in that Pfizer's pipeline is among the healthiest in the business. With more than six dozen different prospects in its pipeline as of August, Pfizer just needs some of those drug candidates to pan out in order to replace revenue from drugs whose patents have expired or will expire in the near future.

Johnson & Johnson's results a couple of weeks ago show just how much potential the pharmaceutical industry has. J&J managed to boost its drug-segment revenue by almost 10% globally, with strong sales from blockbusters Zytiga and Remicade providing a big boost and leading J&J to increase its guidance for the full year. Those growth levels reflect what Pfizer could do with its pipeline once it works through its patent-cliff issues.

Either way, Pfizer's results will have ramifications for the entire Dow, as the competitive landscape among it and its rivals has ripple effects throughout the health-care industry. If Pfizer can do better than Merck's lackluster results today, it could give health-care stocks a needed boost.

Fool contributor Dan Caplinger has no position in any stocks mentioned. You can follow him on Twitter @DanCaplinger. The Motley Fool recommends Johnson & Johnson. The Motley Fool owns shares of Johnson & Johnson. 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.