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.

Existing home sales, as expected, fell in January, and stocks headed into the weekend little changed after a short week of trading. Next week, Wall Street will await news on whether new home sales were also soft in January, and what the U.S. fourth-quarter GDP looks like. GDP grew at a 4.1% annual pace in the third quarter last year -- the fastest rate in nearly two years -- and investors are anxious to see if the growth continues. With little to talk about until next week, the S&P 500 Index (^GSPC 0.55%) lost three points, or 0.2%, to end at 1,836. 

But just because the stock market went sideways today doesn't mean individual stocks were immune from major swings. In fact, if you looked at the three worst stocks in the S&P and had to guess what was happening in the world, you might think we were on the verge of a nuclear war. Cabot Oil & Gas (CTRA 0.41%), for instance, slumped 8.2% Friday, ending as one of the worst performers in the index for a second straight day. Although Cabot Oil & Gas managed to beat earnings and revenue expectations for the fourth quarter, average realized natural gas prices fell 12% in the period, worrying shareholders. 

Gold and copper producer Newmont Mining (NEM 0.72%) shed 4.4% on Friday as investors rushed for the exits after a weak quarterly report. Despite staging a slight comeback in 2014, gold prices are still down more than 15% in the last year, as stocks posted huge gains, and the Federal Reserve began cutting back on its monetary stimulus efforts. Newmont Mining posted earnings per share of $0.33 in the fourth quarter, 25% less than Wall Street estimates, as sales fell more than 12%. Defensive investments like gold don't have the best outlook right now as the U.S. economy recovers, the employment landscape stabilizes, and corporate America mints money like never before.

Health-care management company Express Scripts (ESRX) lost 4% in trading today, as Wall Street took issue with its quarterly report. Even though Express Scripts met fourth-quarter earnings expectations, beat sales estimates, and projected 2014 earnings growth in line with Wall Street forecasts, the fact that Express Scripts wasn't blowing expectations out of the water seemed to peeve shareholders. Sure, with a 33 P/E, high growth is built into the current price, but the company's self-professed expectations for 10% to 20% annual EPS growth during the next several years ain't so shabby.