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.

After briefly hitting an all-time high yesterday, the S&P 500 Index (SNPINDEX:^GSPC) eased lower today as seven of the market's 10 sectors finished in the red. Earnings season is still in full swing, and with new home sales, jobless claims and fourth quarter GDP all set to be released by week's end, we may see larger swings in the days ahead. Today, though, the S&P 500 was relatively stable, losing just 2 points, or 0.1%, to end at 1,845. 

In sharp contrast to the market's broader serenity on Tuesday, three members of the S&P were anything but stable, finishing with steep losses. Shares of Cliffs Natural Resources (NYSE:CLF), for instance, lost 4.8%, ending in the depths of the benchmark index for a second straight day. Cliffs Natural Resources mines for coal and iron ore -- both steel components -- and as such is sensitive to the supply of and demand for steel. Reports that Asian banks are approaching real estate lending more cautiously caused steel prices to stumble yesterday; decreased lending would imply softer steel demand from Eastern builders. 

Shares of Monster Beverage Corporation (NASDAQ:MNST), makers of the eponymous Monster energy drink, slumped 4.2% today. Despite no changes to the company's underlying fundamentals, the stock took a hit after Longbow Research analysts decided to downgrade shares to "underperform" from "neutral." The stock's current $12 billion valuation reflects high growth expectations from Wall Street – expectations that Monster has been able to meet and exceed in recent years as the stock nearly quadrupled in the last five years. But with health concerns about the impact of energy drinks on young adults more prominent than ever in the public arena, Monster faces a distinct regulatory risk in the years ahead.

The last of the day's laggards, Oklahoma-based WPX Energy (NYSE:WPX), which explores and develops oil and natural gas properties, shed 3.5% Tuesday, as pre-earnings jitters sent shares lower in trading. WPX Energy reports quarterly earnings on Thursday, and investors are hoping fiscal 2013 will be a turnaround year for the company, which saw sales fall in each of the four previous years. Analysts expect 2013 revenue to reverse this ugly trend, although they also expect WPX to suffer a fourth straight year of losses. Wall Street doesn't expect the company to return to profitability this year either, so keep that in mind before betting on a turnaround. 

John Divine has no position in any stocks mentioned. You can follow him on Twitter, @divinebizkid, and on Motley Fool CAPS, @TMFDivine.

The Motley Fool recommends and owns shares of Monster Beverage. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.