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 given up substantial ground today, falling 92 points as of 12:30 p.m. EDT on worries about sluggish global industrial activity. Yet tomorrow, 3M (NYSE:MMM) and Microsoft (NASDAQ:MSFT) will add their names to the list of Dow component stocks giving their quarterly reports. With the two companies representing important parts of the U.S. economy, they could have a big influence in moving the Dow tomorrow and for the rest of the week.

3M begins the day with its report before the bell, with a conference call to follow at 9 a.m. EDT. Microsoft reports after the market close, and it will talk to investors on a call scheduled to begin at 5:30 p.m. EDT.

Both reports will have big implications for the companies and their respective sectors. Microsoft has struggled to keep up with its big-tech competitors in the mobile revolution, with its smartphone and tablet products badly lagging behind those of its more successful rivals. Even with major moves like the Nokia purchase and the release of updated versions of its Windows 8.1 operating system and its Surface Pro 2 tablet, Microsoft still needs to prove that it can hold off its mobile competitors. Given threats to its operating system and office software products as well, Microsoft faces a big challenge.

Meanwhile, 3M is trying to win back its reputation for innovation with its wide range of businesses. The conglomerate has no shortage of potential opportunities, ranging from hot areas like renewable energy and health care records to its more reliable dominance in the household and office products realms. Continued initiatives to implement shareholder-friendly share repurchases would excite many shareholders, but in the long run, 3M needs to demonstrate its ability to come up with brand-new products that push it forward in customers' eyes.

Fool contributor Dan Caplinger has no position in any stocks mentioned. You can follow him on Twitter @DanCaplinger. The Motley Fool recommends 3M. The Motley Fool owns shares of Microsoft. 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.