After five years of gains in one of the most powerful bull markets in recent memory, the Dow Jones Industrials (DJINDICES:^DJI) have gotten off to a slow start in 2014. Even after a strong February, the Dow (^DJI) is still down about 250 points year-to-date. But 10 of the 30 stocks in the Dow Jones Industrials (^DJI) have gained ground so far this year, and topping the list are four stocks that might surprise you: Merck (NYSE:MRK), Caterpillar (NYSE:CAT), Pfizer (NYSE:PFE), and Disney (NYSE:DIS).

Of these four stocks, Caterpillar (CAT) is the most surprising with its 7% gain. The construction- and mining-equipment maker has struggled for a long time, suffering as economic conditions both in the U.S. and in key foreign markets like China contributed to a long downturn in equipment sales. Even now, prices for mined products remain depressed, and even though conditions in the U.S. have unquestionably improved, other troubling areas around the world haven't shown unambiguous signs of imminent recovery. For now, it has been enough to see signs of hope in the company's guidance for 2014, but Caterpillar (CAT) will still have to work hard in order to achieve those goals without substantial macroeconomic help.

For Merck (MRK) and Pfizer (PFE), with gains of 13% and 6% respectively, the news makes considerably more sense. The market darlings of 2014 thus far have been biotech stocks, with news of several promising treatments and a rise in merger and acquisition activity causing last year's big run-up in the sector to continue. Merck and Pfizer don't have a substantial presence in biotech, but they nevertheless have the ability to benefit from the advances that more biotech-focused peers make, as both Pfizer (PFE) and Merck (MRK) have sought out partnerships with key companies that they believe can bolster their own drug-development pipelines. As investors start to see light at the end of the patent-cliff tunnel that both companies have had to deal with, gains for these pharma giants could continue as long as the rest of the sector holds up well.

Finally, Disney (DIS) has climbed 5% in 2014, with its attractive mix of entertainment divisions driving the stock to all-time record highs. Between its successful television media properties and a strong year at the box office in 2013, the entertainment giant has a lot of momentum carrying it forward. Moreover, with an impressive slate of feature films scheduled for this year, Disney (DIS) has the capacity to keep producing blockbuster results that could drive even more profits in the long run, especially if ongoing efforts to reap big financial rewards from streaming-video specialist Netflix and other content providers prove successful.

Two months isn't a long time in the investing world, and these stocks could reverse course and underperform for the rest of 2014. But all four have the capacity to produce even bigger gains under the right circumstances, and only time will tell which direction their share prices move this year and beyond.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.