The markets have been on quite a ride lately. The Dow Jones Industrial Average (DJINDICES:^DJI) was up 149 points on Friday, fell 129 points on Monday, and then closed up another 99 points yesterday. The S&P 500 (SNPINDEX:^GSPC) and the Nasdaq have been moving right along with it. Today, investors got to relax a little and assess some recent stock movements, with the Dow moving higher by only 7 points, or 0.05%, while the S&P added a mere 0.83 points, or 0.05%, and the Nasdaq dropped 3.1 points, or 0.1%.

With no major news pertaining to either UnitedHealth Group (NYSE:UNH) or Pfizer (NYSE:PFE) and shares falling by 0.68% and 0.69%, respectively, it's fair to say that investors believed today that the two companies' stock prices have moved too high, too quickly. UnitedHealth has received a number of stock upgrades since the company announced better-than-expected quarterly earnings, which have helped send the stock up 5.73% year to date.

As for Pfizer, while the drug manufacturer also announced earnings that beat quarterly results, the competition that the big drug companies face from generic-drug companies seems to be getting the best of them. Merck, for one, recently announced poor earnings and placed some of the blame on the increased competition from the generic manufacturers. It may just be a matter of time until Pfizer falls prey.  

Shares of General Electric (NYSE:GE) fell by 0.44% today. This afternoon, news broke that Alstom, the largest manufacturer of hydropower equipment, will take General Electric's spot as provider to Renova Energia of South America. Renova placed an order for 440 onshore turbines at a cost of $1.35 billion.  

Finally, Caterpillar (NYSE:CAT) lost 0.75% during today's trading session. The company's earnings per share are expected to fall 4.4% in 2013, and Caterpillar has given guidance of $7.00 to $9.00 per share in the year. With a range that wide, management is basically telling investors they aren't sure what will happen over the coming months. Over the past 30 days, 11 analysts have reduced their estimates, which has brought the Zacks polled consensus from $8.69 down to $8.25.

Fool contributor Matt Thalman has no position in any stocks mentioned. Follow Matt on Twitter: @mthalman5513. The Motley Fool recommends UnitedHealth Group and owns shares of General Electric. 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.