Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

Perhaps asking for a continuation of yesterday's strong move higher would be too much to ask for optimists who saw the broad-based S&P 500 (SNPINDEX:^GSPC) dip for the 10th time in the past 13 sessions.

The big news moving the markets today was the release of the Fed's minutes from its meeting in late July, which showed an almost unanimous agreement among the 12 members of the Federal Open Market Committee that now was not the proper time to change its ongoing $85-billion monthly stimulus package. While good news, it didn't exactly lend any clues as to when the Fed will indeed begin paring back QE3, which is what the market was really hoping to find out.

On an even more downbeat note, the Mortgage Brokers Association's weekly mortgage application data showed a 4.6% drop in demand last week. The decline follows mortgage lending rates matching their highest levels for the year, and marks a decline of more than 50% since May in mortgage applications. The quicker rates rise and applications decline, the more worry for the still fragile housing sector.

By the end of trading, the S&P 500 had declined by 9.55 points (-0.58%) to close at 1,642.80. The S&P 500 is now off nearly 4% over the past two-and-a-half weeks.

Topping all S&P 500 stocks today was GPS-device maker Garmin (NASDAQ:GRMN), which added 4.8% after receiving an upgrade to neutral from sell at Goldman Sachs. The reason for the upgrade stems from the introduction of a new line of action camera products from Garmin known as VIRB and VIRB Elite, which caused Goldman to ever-so-slightly bump up its EPS projections on the company. As for me, I'd like to remind you that analyst actions rarely offer any long-term impact on a company, so I'd take today's move with a grain of salt. Garmin still has a lot of inconsistencies to work through, with smartphones and tablets taking away the need, in some cases, for a GPS device. This has the potential to put the bulk of its long-term business model at risk.

Home improvement retailer Lowe's (NYSE:LOW) jumped 3.9% today after reporting better-than-expected results in its second quarter, and boosting its full-year guidance. For the quarter, Lowe's delivered a 10% increase in revenue, to $15.7 billion, and EPS of $0.88, which was up significantly from the $0.64 reported in the year-ago period. Comparatively speaking, Wall Street expected just $15.1 billion in revenue and $0.79 in EPS. A long-sustained housing rally and historically low interest rates have spurred consumers to spend heftily in the home improvement sector, which is helping beef up Lowe's bottom line. However, if the Fed pares back QE3 soon, weaker links like Lowe's may find growing its bottom line very difficult without tight cost controls.

Finally, payment processor Visa (NYSE:V) gained 3% after the Federal Reserve announced that it would appeal a recent ruling on debit-card transaction fees. Visa, which owns a huge percentage of the U.S.-based debit-card payment processing market, has a lot at stake. If a debit-fee cap is put in place, then it would be likely that some merchants may switch to MasterCard (NYSE:MA), which currently has smaller debit-card market share in the U.S. While investors may be getting tied up over this ongoing swipe-fee issue, I'd instead point to both Visa and MasterCard's growing overseas opportunity. That's where the big money lies, and why Visa and MasterCard have decades of double-digit growth potential still to come.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.