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.

For a second straight day we were devoid of any major economic drivers, and the S&P 500 (SNPINDEX:^GSPC) instead succumbed to profit-taking and weak commodity prices following what's been a tremendously bullish start to the fourth quarter.

If there was a dominant story, it was all about weak commodity prices. Gold has broken below $1,270 per ounce and oil dipped below $94 per barrel, marking recent lows that could signal the potential for an extended downtrend in commodity-based stocks. A drop in oil prices should be welcome news for consumers at the pump, but investors in commodity-based companies ranging from oil and gas drillers to gold and coal miners are taking it on the chin and dragging the S&P 500 down.

By day's end, the S&P 500 clawed its way back from its lows, ending down by 4.20 points (-0.24%) to close at 1,767.69. That is still less than 1 percent from a new all-time high.

Topping the charts among S&P 500 stocks today was America's largest homebuilder, D.R. Horton (NYSE:DHI) which advanced 4.7% after reporting fourth-quarter earnings results before the opening bell. For the quarter, D.R. Horton delivered a whopping 40% increase in homebuilding revenue to $1.8 billion with net income jumping an equally impressive 39%, to an adjusted $0.40 per share, matching Wall Street's lofty expectations. Most importantly, and the reason shareholders are really excited, D.R. Horton's average home sales price was up 15% year over year, meaning the company is holding the line with its pricing even with interest rates higher now than they were a year ago. With D.R. Horton operating in some of the nation's hottest housing markets it could certainly have room to march higher.

Also heading higher today was information technology service specialist Xerox (NYSE:XRX) which tacked on 4.1% after boosting its share repurchase program by $500 million and following positive comments made by CEO Ursula Burns at its annual investor conference. Burns set the bar for the upcoming year at an adjusted earnings per share of $1.10-$1.16, which is pretty much in-line with current Street expectations of $1.15 in full-year profits. But, what's really exciting investors, aside from the buyback announcement, is the expectation that Xerox will utilize IT-service contract gains to push its service revenue from 56% of total sales now to 66% by 2017. I've long contended that Xerox is a very sneaky growth play in the health care sector and could be primed for strong growth under Obamacare.

Finally, sticking within that sector, shares of hospital operator Tenet Healthcare (NYSE:THC) gained 3.5% after receiving positive comments from JPMorgan Chase. The covering analyst, Justin Lake, said he views Tenet's weak fourth-quarter guidance as a buying opportunity. Lake believes the combination of Tenet and Vanguard Health Systems (Tenet just completed the acquisition) should drive cost synergies, and that Tenet's fourth-quarter earnings estimates are typically conservative.  I'm not nearly as convinced. I'd contend that a lot of promise of higher revenue collection due to more people being insured under Obamacare has been baked into Tenet's future results, but many of the states it operates in fall under the federally run where few people have been able to register. I believe Tenet could be set up to disappoint investors moving forward.

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.