Alcoa Earnings, Alcoa Earnings Announcement (Report) ,Alcoa News

U.S. stock futures were mixed on Wednesday morning, trading in a tight range as investors awaited results from Alcoa (NYSE: AA) this afternoon that kick off second quarter earnings season. Despite the debate whether Alcoa is a good barometer for economic activity and what's to come as far as corporate results, it seems Wall Street is still on edge ahead of the results.

Also making the headlines this morning is Google's (NASDAQ: GOOG) announcement of a challenge to Microsoft's (NASDAQ: MSFT) operating system as well as NRG Energy (NYSE: NRG) rejection of Exelon's revised hostile takeover bid of $8 billion in stock because it is undervalued.

Overseas, the same concerns over U.S. corporate profits weighed on stocks. World stock markets fell Wednesday amid mounting worries about the speed of any global economic recovery. In Asia, Japan's benchmark Nikkei 225 stock average tumbled 227.04 points, or 2.4 percent, to 9,420.75 - its sixth fall in a row and its lowest close in six weeks. European markets followed suit, declining for the fifth straight session on Wednesday despite a report German industrial output surged the most in almost 16 years in May, adding to signs a recession in Europe's largest economy is bottoming out.

Meanwhile, G8 leaders prepared for their summit in Italy that begins today. Draft documents seen by Reuters stated they "significant risks remain to economic and financial stability" and may need further help.