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 Industrials (^DJI 0.06%) might not look like it's performing well today, but a loss of 110 points as of 12:30 p.m. EST is actually a vast improvement over the drop of more than 230 points that the average suffered at its lowest point today. With January representing a sour start to the Dow's 2014, many investors are increasingly nervous about the market's future. But a close look at Merck (MRK 0.49%), Caterpillar (CAT -0.53%), and United Technologies (RTX 0.59%) -- the only three stocks that have moved up in price so far in 2014 -- points to some useful lessons that investors should take in assessing the Dow's prospects for the future.

The most obvious thing that these three companies point to is that you can't count on a unified theme among winning stocks. These companies have very different corporate focus areas, and while they share some common exposure to general economic conditions, the ways their respective industries react to those conditions differ greatly. United Technologies, for instance, has capitalized on the immense growth in corporate aircraft demand, while Caterpillar has struggled under lack of sales volume for its heavy equipment -- representing two ends of the same economic spectrum. Merck's health care emphasis makes it much less cyclical than either United Technologies or Caterpillar, yet it has still defied the general market trend.

Second, looking for catalysts for share-price gains often pays off. Merck has worked hard to reestablish and strengthen its drug pipeline over the years despite fighting against its patent cliff, but its stock's movements haven't reflected consistent investor confidence in the pharma giant's eventual success. Yet positive developments in key treatment areas, as well as smart corporate decisions, have proven to be a driver for the stock in January. Similarly, enthusiasm over the latest earnings news from United Technologies emphasized all the positive results that the conglomerate has achieved recently, concentrating positive investor sentiment toward a rising share price.

Finally, even struggling stocks can turn themselves around successfully. For Caterpillar, an eventual recovery still seems far away, but investors are starting to recognize how conditions might change in its favor. And while Merck's sales won't recover to their former glory right away, given enough time new drugs will replace old blockbusters and restore growth.

Even in a down market, it's important to look at the best performers to see what they're doing right. Often, the lessons you learn from them are ones you can apply to find other great stocks that can do well even when the rest of the market is suffering.