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.

With reports streaming in this morning that Black Friday shopping results were weak, all of the major U.S. indexes ended the session lower. The Dow Jones Industrial Average (^DJI -1.68%) closed down 77 points, or 0.48%, while the S&P 500 lost 0.27% and the Nasdaq fell 0.36%. Although 141 million shoppers hit stores over the weekend, beating reports of 139 million last year, average spending fell from $423.55 to $407.02.

Another reason the indexes moved lower may have been the same reason shares of Home Depot (HD -1.11%) dropped by 1.12% today: a mediocre construction spending report. While the seasonally adjusted annual rate of construction spending in October hit $908.4 billion, higher than the estimated $901.2 billion for September and 5.3% above the October 2012 figure of $863.1 billion, residential spending came in lower in October ($332,885, seasonally adjusted) than in September ($334,487). The decline came into play from single-family homes, as multi-family residences showed an increase from September to October. That would imply we will see more renters in the future, which is not a demographic that helps growth at home-improvement stores. It could also be a sign that Americans still don't feel confident about the economy in general.  

Home Depot was also hit by a poor rating from Standpoint Research. The firm initiated coverage at a sell rating and assigned a price target of $68 per share, which implies almost a 16% downside to the stock.  

Other downgrades hurt the Dow today, as shares of 3M (MMM -1.20%) declined 4.37% after the stock was hit by a rating change from Morgan Stanley. The firm cut the stock from "equal weight" to "underweight," believing that 3M will have a hard time growing revenue and earnings organically. Over the past few years the company has acquired its growth, which works for a time but may have now run its course. Unless 3M can improve its product mix through innovation, it could struggle in the coming quarters or years, as the current valuation may be a little stretched at today's price.  

Outside the Dow we saw another downgrade causing a big move at Urban Outfitters (URBN -0.82%), whose shares fell 3.49% today. Analysts at Sterne Agee lowered Urban Outfitters' rating from "buy" to "neutral," noting a lack of confidence in management's ability to continue to quickly adjust merchandise in the future. Merchandise inventory is a huge factor for retail companies, and as Urban Outfitters operates in the teen space, which constantly sees quickly changing trends, it could take just one misstep to cause big problems.