Major U.S. stock indices fell at the open on Wednesday, with the S&P 500 and Dow Jones each down 0.6 percent and the Nasdaq composite down 0.8 percent. Super Micro Computer shares dropped 13.5 percent after the company announced plans to raise $7 billion, while Micron Technology shares declined 2.8 percent. A CPI reading of 4.2 percent, the highest level in three years, was also reported.