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.

Stocks have gotten off to a slow start today, with the markets bouncing around breakeven and the Dow Jones Industrial Average (^DJI -0.98%) struggling to hold on to modest gains. As of 2:15 p.m. EST, the Dow's picked up about 20 points, although most of the index's blue-chip member stocks are up in the green today.

General Electric's (GE 1.30%) putting in a good day for investors, gaining about 1.1% so far to rise to the top of the Dow. On the other side of the index, however, poor sales have sent McDonald's (MCD -0.42%) stock down 1.1%. Let's catch up on what you need to know.

The Golden Arches misses the mark
McDonald's today reported a 0.5% uptick in November sales, a number on par with October's monthly sales gain. However, the biggest concern for the fast-food chain came in the United States, where sales at locations open at least a year nosed down by 0.8%. That missed the 0.3% gain that analysts expected by a big mark, and it's a telling sign that McDonald's hasn't been able to beat back strong competition in the sector so far.

It's been a rather rough year for McDonald's stock, as shares have climbed only around 7.4% despite the Dow's big gain. There were some positive notes for the company in today's release: European same-store sales jumped nearly 2%, with Russia, France, and Britain leading the way. However, it's critical that McDonald's also light a fire under its Asia, Middle East, and Africa segment, which saw sales plummet by 2.3% during November. Considering the emerging market potential in this geographic area, McDonald's can't afford to let rivals continue to push its presence down in developing regions.

GE's having a much better day with its stock, which has also done much better year to date than the likes of McDonald's. GE's shares have climbed about 26% through 2013 so far, a spectacular gain for such a diversified company. The company's done a good job keeping its financial performance on track recently as well, posting a net profit margin of more than 9.5% over the trailing 12 months.

But is there cause for concern from GE's broad business reach? While GE's aviation unit has been a big winner, seeing revenue climb by more than 8% year over year through the first nine months of 2013 -- a great posting for the company's second-largest business by revenue -- GE's power and water segment, its bread and butter and largest business by sales, has seen its performance fall off sharply in 2013. Sales of this segment dived by 17.5% during that same time frame, and it's the big reason why GE's overall revenue hasn't been able to find much footing during 2013, despite the company's otherwise solid performance.

However, if GE's other businesses can continue to rise, this company can afford some slight drawdown in this area. Diversity is GE's strength, and one that investors can rely on for great returns.