Stock markets are down once again today, driven lower by weak economic data and less-than-inspiring earnings. The Conference Board said its Leading Economic Index fell 0.1% in March, whereas economists had expected 0.2% growth. The index is a weighted gauge of 10 indicators designed to give an indication of business cycles, so it's a broader reading than most -- and that's why investors are concerned by the reading. This is one of the bits of bad news driving the Dow Jones Industrial Average (DJINDICES:^DJI) and the S&P 500 (SNPINDEX:^GSPC) down 0.57% and 0.72%, respectively, near the end of trading.

UnitedHealth Group (NYSE:UNH) is the biggest decliner on the Dow, falling 3.4% after reporting earnings. Revenue rose 11% in the first quarter to $30.34 billion, but net income fell 14% to $1.19 billion, or $1.16 per share. Those numbers weren't wildly out of line with expectations, but when management said full-year revenue would be $122 billion, well below a previous estimate of $123 billion to $124 billion, the sell-off was on. 

Bank of America (NYSE:BAC) is the only stock that came close to matching UnitedHealth Group, falling 3% on continued earnings worry. The megabank was the biggest loser yesterday, and after a night to digest the company's first-quarter earnings report, investors aren't feeling any better about it. To make matters worse, Morgan Stanley reported earnings this morning, and after you strip out accounting charges, its profit fell from $0.71 a year ago to $0.61 in the first quarter. Banking stocks have been on a tear in 2013, and that bullishness seems to be reversing quickly now that earnings are out.

On the positive side of the market, shares of Verizon Communications (NYSE:VZ) are up 3.1% today after the company announced first-quarter revenue of $29.4 billion and net income of $1.95 billion, or $0.68 per share. Revenue was a touch lower than expected, but EPS beat expectations by $0.02, and shares were off to the races. Not surprisingly, results were driven by Verizon Wireless, which added 677,000 new devices to its rolls this quarter. The momentum continues for Verizon Wireless, and this is the only cell carrier I'd bet on today.  

Fool contributor Travis Hoium has no position in any stocks mentioned. The Motley Fool recommends UnitedHealth Group. The Motley Fool owns shares of Bank of America. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.