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 S&P 500 Index (^GSPC -0.46%) roared nearly 30% higher in 2013, logging its best year since 1997 as the U.S. economy continued to show slow-but-steady improvement, and interest rates remained subdued. After finishing the year at all-time highs, 2014 got off to a rocky start as about two in every three stocks lost ground on Thursday on the heels of disappointing jobless claims data. The S&P ended with losses of 16 points, or 0.9%, to end at 1,831. 

Even though Pioneer Natural Resources (PXD -0.13%) stock had lots of company today, it still stood out as a major laggard, shedding 4.1% Thursday. Pioneer Natural Resources produces oil and natural gas; however, because all 10 market sectors ended in the red today, no business model was immune from losses. Interestingly, profit-taking was prominent on Wall Street today as some of the strongest performers in 2013 ended as some of 2014's steepest early decliners. Shareholders are forgiven for wanting to cash in on Pioneer's 60% year-over-year surge, but true long-term investors, who still believe in natural gas' viability, may still want to hold on. 

Mining equipment maker Joy Global (JOY) lost 3.6% in trading, as shares of the industrial goods company ended as casualty of its weak sector, which was off 1.3% Thursday. Considering Joy Global's high "beta" -- a ratio of an individual stock's volatility in comparison to the broader market -- of 2.2, a second look at today's slump reveals nothing particularly shocking. Additionally, investors can take solace in the fact that the company is consistently churning out higher net profit margins than industry leader Caterpillar. 

Lastly, WPX Energy (WPX), which, like Pioneer Natural Resources, produces oil and natural gas, fell 2.8% today. Aside from the systemic bearish sentiment in the market, oil producers in particular faced pressure, as oil prices slumped 3%. Ending at $95.44 a barrel, the price of "black gold" trended lower on concerns of higher supply and a strengthening dollar. WPX Energy stock initially took a hit in the week before Christmas when CEO Stephen Hill was unexpectedly ousted, though the stock has since recovered.