U.S. stocks are mixed on Tuesday as investors eye Slovakia's vote on the EFSF expansion and Alcoa's (NYSE:AA) earnings report.

The S&P 500 Index is up 0.18 points, or 0.02 percent, to trade at 1,195.07 at 1:24 p.m. ET.  The Dow Jones Industrial Average is down 8.37 points, or 0.07 percent, to trade at 11,424.81.  The Nasdaq Composite is up 0.36 percent.

After the market closes on Tuesday, investors will greet the unofficial beginning of third quarter earnings season with Alcoa's earnings report.

Investors seem upbeat as Alcoa shares have surged 2.78 percent in afternoon trading.

Apple (NASDAQ:AAPL), the second largest U.S. publicly traded company, is up 2.38 percent on the strength of iPhone 4S sales.

U.S. stocks and global risk assets, however, are weighed down by Slovakia's looming vote on the expansion of the Eurozone bailout fund EFSF.

Slovakia is the last Eurozone member to not yet approve the expansion.  Some Slovak politicians are against the idea of contributing to a fund that will bail out the profligacy of Greece, which is a richer country than Slovakia.

Still, Slovak Prime Minister Iveta Radi?ová vowed to gather enough support in her country to pass the expansion.

The Slovak vote is definitely putting a layer of uncertainty around the EFSF package but I think this is temporary and political jockeying, said Brad Bechtel, managing director at foreign exchange services firm Faros Trading.