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.

A day after stocks fell off a cliff, the Dow Jones Industrial Average (DJINDICES:^DJI) limped into the weekend, falling 31 points, or 0.2%, today -- its worst week of the year -- down over 2%. After disappointing reports by Wal-Mart and other retailers gave investors concern about weakening consumers yesterday, today, the University of Michigan reported that consumer sentiment had declined from 85.1 in July, to 80.0 in August, missing expectations that were also at 85.1.

The index showed that American consumers were growing nervous over rising interest rates, and their view of current economic conditions substantially weakened. Though the 80.0 reading is still better than it was a few months ago, the decline could present further problems for retailers and the economy as a whole this quarter. Elsewhere, productivity and labor costs showed surprising increases in Q2, meaning that workers are getting paid more, and manufacturers are operating more efficiently, both of which favor the recovery. Also, July housing starts and building permits both came slightly ahead of expectations and above June's mark, indicating that homebuilding has not yet peaked.

Verizon (NYSE:VZ) was the biggest loser on the Dow today, falling 1.7%, as the telecom giant announced it was reconsidering its plan to enter the Canadian market by acquiring Wind Mobile. Verizon has faced opposition in its quest to spread north of the border from Canadian telecoms and unions, which have claimed that the U.S.'s No. 1 wireless provider is taking advantage of rules designed to benefit smaller competitors. Verizon said it would hold off on the acquisition of Wind Mobile and Mobilicity until a government auction for wireless spectrum in January.

Pfizer (NYSE:PFE) was also taking a hit, down 1.5% after the U.K.'s National Institute for Health and Care Excellence recommended against using its lung-cancer drug Xalkori, saying the cost was too high. While the decision does not doom the new drug, it does add a hurdle to Pfizer's goal of seeing it generate $2.5 billion in revenue. Pfizer had already offered a discount on the drug, which carries an $80,000 price tag, but may have to sweeten the deal in order to get the British to accept it.