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.

For every one stock that fell, two advanced on Tuesday as the stock market resumed trading after the long Presidents' Day weekend. With no major macroeconomic news to speak of, the broader market was relatively stable today. Treading water, the S&P 500 Index (^GSPC 0.17%) tacked on just 2 points, or 0.1%, to end at 1,840. Of course, just because "all's quiet on the Western front" doesn't mean there were no casualties, as today's biggest laggards in the S&P 500 will clearly illustrate. 

Missouri-based railroad Kansas City Southern (KSU) was the index's worst decliner, falling 4.5% on Tuesday. You wouldn't know by the company's all-American name that it derives nearly 50% of its annual revenue from railroads in Mexico, where the business enjoys a lucrative, exclusive agreement with the Mexican government. The 30-year agreement with Mexico, signed in 1997, granted Kansas City Southern exclusive rights to networks that the government is now trying to rescind in the name of competition. 

Trash services expert Waste Management (WM 0.15%) stock also lost 4.5% today, as the company's fourth quarter disappointed. Both earnings and sales came in below Wall Street expectations, and Waste Management also issued underwhelming profit guidance for the coming year. Sales in the fourth quarter were up less than 2% year-over-year, highlighting the fact that this low-growth company may only be appropriate for the patient, long-term income investor. Speaking of income investors, Waste Management's annual dividend, which already stood around 3.3%, was boosted to 3.6% Tuesday, so there is a silver lining to today's news.

Finally, the esteemed Coca-Cola Company (KO -0.61%) shed 3.8% Tuesday -- dragging the Dow down with it -- after the beverage giant's quarterly earnings failed to impress. When businesses get to be the size of the $165 billion Coca-Cola Company, investor concerns tend to differ dramatically from more moderately sized corporations. For example, Coke's worldwide sales fell 2% last year -- even though its sales volume increased by 2% -- because of currency fluctuations. But as American consumers become more health-conscious and wary of sugary drinks, Coke has to battle some fundamental changes to its most lucrative market: the U.S.