The U.S. stock index futures point to a flat open Wednesday as investor sentiment continues to be weighed down by concerns of debt crisis in the euro zone and weakening growth in China affecting the global economy.

The futures on the Dow Jones Industrial Average were down 0.07 percent, the futures on the Standard & Poor's 500 Index were up 0.07 percent and those on the Nasdaq 100 Index were down 0.04 percent.

Investors are expected to focus on the Federal Reserve's Beige Book, which will be reported Wednesday. The Beige Book, which is a report on current economic conditions in each of the 12 Federal districts in the U.S, will give a picture of economic trends and challenges in the country.

Investors are concerned as the earning season commenced in the U.S. Tuesday with Alcoa Inc announcing its quarterly report. The company, which is the largest U.S. aluminum producer, lowered the global consumption forecast for 2012 to 6 percent down from 7 percent announced in July citing the slowdown in China’s economy as the main reason.

On Tuesday, the U.S. markets fell as investors continued to have concerns that the weakening of global economic conditions has affected the quarterly earnings of companies. The Dow Jones Industrial Average fell 0.81 percent, the S&P 500 Index was down 0.99 percent and the Nasdaq Composite Index declined 1.52 percent.

European markets fell Wednesday as investor sentiment turned negative with the revival of the concerns over the debt burden faced by the euro zone and the weakening global economic growth. The International Monetary Fund, while releasing its Global Financial Stability Report Wednesday, warned that the debt crisis in the euro areas continues to be a major threat to global financial stability.

"Despite many important steps already taken by policymakers, this agenda remains critically incomplete, exposing the euro area to a downward spiral of capital flight, breakup fears and economic decline," the IMF said.

London's FTSE 100 was down 16 points, Germany's DAX 30 index fell 17.01 points and France's CAC 40 declined 4.62 points.

Asian markets fell Wednesday as investor sentiment was weighed down by concerns that China’s economic slowdown would impair the growth of the global economy.