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 starting the week off on a great note and being up 299 points after Wednesday's close, the Dow Jones Industrial Average (^DJI -0.11%) tried its hardest to give everything back before the end of trading on Friday. But as the closing bell rang to wrap up the week and despite moving lower by 185 points in one day, it was still higher by 75 points, or 0.47%, for the week.

The other two major indexes, the S&P 500 and the Nasdaq, performed much better this past week, gaining 1.3% and 1.41% during the past five trading sessions. The massive moves began with the Federal Reserve's announcement on Wednesday that it won't yet start tapering its $85 billion-a-month bond-buying program, and they continued as investors came to grips with what the lack of tapering means for the economy. Concerns about the debt crisis in Washington on Friday played a role as well.

Before we jump into the big losers of the week, let's quickly take a look at the Dow's top performer. Travelers (TRV -0.41%) rose 2.99% this past week as investors flocked to the stock, especially after FBR Capital on Thursday increased its rating from "market perform" to "outperform" and raised its price target to $94. Travelers and the other insurance companies have been lucky this year, as what many believed would be a terrible hurricane season has so far been a goose egg. And despite the fires in Colorado, only small claims have hit the major carriers for the past few months. If the weather holds off, investors should see strong profits from Travelers and the other industry players for the third-quarter and full-year 2013 financial reports.  

Last week's big losers
Hewlett-Packard (HPQ 1.55%) was again among the Dow's top three biggest losers this past week. The company faces a number of headwinds as it attempts to turn around its business and focus less on PCs. Two weeks ago, when HP was the only Dow stock to fall for the week, one of the major downward forces was the announcement that Dell was going private and could pose more of a threat as it moved out of the view of Wall Street's prying eyes. This past week, HP fell 3.85% as it faced pressure from being removed from the Dow. Now that it's no longer part of the index, many hedge funds, index funds, and large institutional shareholders will no longer be forced to hold the company because of their fund guidelines.

Caterpillar (CAT 0.07%) was another big loser, falling 2.6% last week. The bulk of the drop came on Friday, after the company released dismal sales numbers for machines during June, July, and August, suggesting that revenue and most likely profits will be down for the third quarter of 2013. In August, worldwide machine sales fell 10% when compared with the same month in 2012. That decline came after the Asia/Pacific market slid 30% and what had been the company's bright spot, Latin America, fell 3%. As for June and July, sales fell 8% and 9%, with the Latin American market standing as the only region to post positive year-over-year sales figures.  

Finally the Dow's biggest loser of the week was UnitedHealth Group (UNH 0.23%), which lost 5.25%. The fall was a gradual one all week, as investors begin to look ahead to Oct. 1, the first day the Obamacare exchanges will be open for business. UnitedHealth and the other major health-care insurers have been hesitant to enter the exchanges in every state, because of the uncertainty of how they will ultimately affect the health-care industry as a whole, and companies' revenues and profits in particular. And with UnitedHealth being up more than 35% year to date, taking profits off the table during a time of uncertainty is never a terrible idea.  

The other Dow losers this week:

(For more information on why shares of the other losers fell lower this past week, click on the links.)