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.

So far today, investors are getting a reminder of how market-moving news can all hit at the same time. The Dow Jones Industrials (DJINDICES:^DJI) is down 115 points as of 11 a.m. EST as the average digested the latest results from earnings season, ongoing concerns about emerging markets, and predictions about the Federal Reserve's monetary policy announcement this afternoon. On the earnings front, Boeing (NYSE:BA) and AT&T (NYSE:T) led the Dow down, even as DuPont (NYSE:DD) and UnitedHealth Group (NYSE:UNH) posted decent gains.

Boeing's nearly 5% plunge came after the aerospace giant gave guidance that didn't match up to investor expectations. Fourth-quarter earnings jumped 29% after adjusting for certain pension expenses, coming in well in excess of what shareholders had expected to see on a roughly 7% jump in revenue. But Boeing doesn't expect very strong core earnings growth for 2014, with gains of less than 2% from its full-year 2013 figure of $7.07 per share reining in the huge optimism that most investors had about the aircraft-maker's stock. Still, with its defense segment looking somewhat more promising, Boeing's dip today could provide a longer-term buying opportunity for those willing to take a short-term risk.

AT&T fell 2.4% on much the same concerns. The telecom company reversed a year-ago loss, with a big pension gain helping to lift earnings. Yet even adjusted earnings were better than investors had expected. Still, some analysts weren't impressed with the company's guidance for 2014 of projected revenue growth of 2%-3% and tepid earnings increases. Citi cut its price target on the stock.

Meanwhile, earnings news indirectly boosted DuPont. Dow Chemical posted a better than expected profit for its most recent quarter, inspiring the company to boost its dividend and its stock repurchase program. Those solid results could point to a better chance of DuPont successfully splitting off its performance chemicals business. Combined with DuPont's efforts to concentrate on growth in the agricultural industry, investors seem to be more optimistic about its prospects.

UnitedHealth rose nearly 1% as investors continue to assess the success of Obamacare enrollment. With just two months left before the March 31 deadline for health insurance coverage to avoid penalties, UnitedHealth could see a last-minute surge in traffic. Without that surge, though, disappointing preliminary figures could point to poor results for UnitedHealth and its insurance peers.

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.