The U.S. stock index futures point to a slightly lower open Wednesday ahead of the Census Bureau's new home sales data.

The futures on the Dow Jones Industrial Average were down 0.04 percent, the futures on the Standard & Poor's 500 index were down 0.16 percent and those on the Nasdaq 100 index were down 0.10 percent.

Investors are expected to focus on August new home sales data to be reported after the markets open Wednesday. The new home sales, measuring the annualized number of new single-family homes that were sold during the previous month, are expected to rise to 380,000, up from 372,000 in July.

On Tuesday, the U.S. markets plunged despite the better-than-expected reports on consumer confidence and home prices as Caterpillar’s profit warning and negative comments from one of the non-voting Fed members weighed on the sentiment. 

S&P 500 declined the most in three months after Philadelphia Fed President Charles Plosser noted the risks emanating from the recently announced third round of quantitative easing and the potential lack of positive impact on the growth and employment. Caterpillar Inc. (CAT) shares declined after the world's largest earth moving equipment maker lowered its fiscal 2015 earnings guidance due to the weak forecast for the next few years.

European stocks plunged Wednesday, tracking losses on Asia and Wall Street overnight following comments by Plosser. The lack of traction in delivering solutions to the regional financial crisis also added to downward move. Large-scale protests against anti-austerity measures in Madrid increased uncertainty over the euro zone crisis and governments' ability to tackle the financial crisis.

London's FTSE 100 was down 61.54 points, Germany's DAX 30 index plunged 112.77 points and France's CAC 40 declined 65.23 points.

Asian markets ended lower, weighed down by the renewed global growth fears and an overnight sell-off in Wall Street. Japanese Nikkei tumbled 2.03 percent, led by declines from exporter and automaker companies’ shares. Automaker shares, including those of Toyota and Nissan, went down after the companies announced plans to restrict production in China as market prospects were seen weakened because of the anti-Japanese sentiment caused by the territorial dispute between the world’s second and third biggest economies.