With the long holiday weekend over, traders are back in full force, and they're not thrilled with what they see. Despite reports of an extremely successful weekend for retailers, the major issues hanging over the markets haven't shown many further signs of resolution, as both the fiscal cliff in the U.S. and the Greek debt crisis in Europe are still locked in negotiations as the parties fail to make substantial progress. The Dow Jones Industrials (DJINDICES:^DJI) are down about 75 points as of 10:45 a.m. EST, while the S&P 500 is down a similar amount in percentage terms.

Among stocks in the Dow, JPMorgan Chase (NYSE:JPM) is the biggest loser, falling nearly 2%. The bank said that Chinese companies are opting to sell more bonds rather than making initial public offerings of stock, which will result in a big shift in its investment-banking revenue within the emerging-market nation. With yields at extremely low levels, borrowing costs are relatively cheap even in China, and JPMorgan helped Internet giant Baidu (NASDAQ:BIDU) with financing earlier this month.

UnitedHealth Group (NYSE:UNH) fell 1.5% after warning that its 2013 earnings would come in below analysts' current expectations. With a new range of $5.25 to $5.50 per share comparing unfavorably with estimates of $5.60, the health insurer expects tighter margins despite higher-than-expected revenue.

Finally, Microsoft (NASDAQ:MSFT) dropped more than 1.5% in early trading. For those who had hoped that the releases of Windows 8 and the Surface tablet would lead to a turnaround in Microsoft shares, November has been a disappointment, with sales boosts slow to emerge. In the long term, though, Fool contributor Jonathan Yates remains bullish on Microsoft's prospects, assuming that Windows 8 will gain traction and make mobile devices based on the operating system competitive.

Fool contributor Dan Caplinger owns warrants on JPMorgan Chase. The Motley Fool owns shares of Baidu, JPMorgan Chase, and Microsoft. Motley Fool newsletter services recommend Baidu, Microsoft, and UnitedHealth Group. 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.