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.

Until now, earnings season has generally had a clear pattern, with one day's news being predominantly positive while the next is dominated by negative developments. Today, though, the Dow Jones Industrials (DJINDICES:^DJI) provided a mix of bullish and bearish reports, and the net effect was a topsy-turvy morning for the average, which was up 48 points as of 11 a.m. EST. American Express (NYSE:AXP) powered the Dow higher, while Intel (NASDAQ:INTC) and General Electric (NYSE:GE) both weighed on the index with substantial declines.

American Express soared almost 6% as investors were pleased with the card company's holiday season. Adjusted earnings rose 15% from the year-ago quarter, and shareholders were willing to ignore a slight shortfall in favor of the optimistic attitude that CEO Ken Chenault gave. An 8% jump in spending among card members confirmed the ongoing trend that luxury shoppers have held up better throughout the economic recovery than less affluent shoppers, favoring AmEx's demographic. In addition, analysts at Susquehanna upgraded AmEx stock, citing factors including lower costs and strategic moves with its travel business as supporting future growth.

Intel dropped 3.5% after reporting a 3% increase in fourth-quarter revenue that sent earnings 6% higher, missing estimates by a penny per share. Even though PC sales held up reasonably well and areas including data-center products produced some substantial growth, investors focused on uninspiring guidance that left them uncertain about how well the company will be able to sustain its momentum in 2014. With the stock having jumped recently, giving back ground made sense in light of the less-than-perfect report.

General Electric fell 2.6% despite delivering a solid fourth-quarter report this morning. A sales gain of 3% and higher margins led to a 20% jump in earnings per share, with six of its seven segments showing revenue growth during the quarter. Oil and gas revenue climbed 17%, confirming the company's strategic vision in boosting its exposure to energy. Backlogs hit record levels, with gains in infrastructure orders pointing to a rebound in long-dormant areas of the economy. Yet again, after the big run in GE stock over the past year, it seems as though investors wanted even better results in order to justify further gains.

Today's stock market action shows how important it is to actually look at earnings reports rather than relying only on share-price moves in response to those reports. Studying only the stock can give you an incorrect impression of the fundamentals of a given business, leading you to make mistakes in your investing decisions.