Over the past two weeks, the S&P 500 (SNPINDEX:^GSPC) has recovered a huge portion of its losses from earlier in 2014. Yet even though the broad-market index is up more than 5.5% since the first trading day of February, a few of the index's component stocks point to the potential for poor performance in the future. Let's take a look at why Cigna (NYSE:CI), WPX Energy (NYSE:WPX), ConAgra (NYSE:CAG), and Kansas City Southern (NYSE:KSU) have entirely missed out on the market's gains and given up ground this month.

Cigna is down 8% since Feb. 3, and those losses came in the wake of its earnings report last week. The health-insurance company noted that its private Medicare business suffered from higher expenses than investors were prepared to see, and concerns about the potential for Medicare reimbursement rates to drop in the years to come is weighing on the entire industry. Moreover, with the impact of the Affordable Care Act as yet uncertain, Cigna has to navigate uncertain waters in figuring out its best strategy for a recovery.

WPX Energy has fallen 7% in February, with the energy exploration and production company struggling with its Marcellus-based operations as well as natural production declines in its older assets. Even though natural gas prices have rebounded recently, they remain historically low in a longer-term context, and WPX therefore had a huge writedown of assets in the Appalachian and Powder River regions. Even as oil production levels rise, the company expects falling overall production throughout 2014, and that's hard for growth-oriented investors to stomach during boom times for the industry.

ConAgra is almost down 4.5% this month after cutting its fiscal-year 2014 outlook last week. The food giant blamed poor performance from its Ralcorp private-label business, which it acquired last year to try to adapt to changing conditions in the grocery industry. ConAgra hopes to adapt its promotional strategy to shore up the ailing business, but competition in the industry is fierce, and so the company will have to act quickly in order to avoid what could become permanently lost opportunities for growth.

Kansas City Southern has also fallen more than 4%, adding to even bigger losses in January after the railroad company failed to meet expectations for revenue and income growth in its fourth-quarter results. Even though total volume rose 2% on an 18% jump in intermodal revenue, Kansas City Southern's coal business dropped by almost a quarter. More importantly, given the huge potential in the railroad industry right now, Kansas City Southern's results make it seem as though the company is missing out in areas where its peers are taking full advantage.

What these drops mean for the market
The question investors have to ask about these four stocks is whether they're special cases or represent dangers that the rest of the market will face in turn. For the most part, these seem to be company-specific problems that are pushing share prices down while leaving all but a couple dozen S&P 500 members with gains in the past two weeks. But the fact that some companies aren't meeting high expectations raises the possibility that others won't as well, and in time, that could bring the whole market back down to earth.

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.