U.S. stock index futures were flat on Wednesday as investors fretted over early rate hikes by the Federal Reserve after strong retail earnings and data showed an economic recovery was on track.At 08:00 a.m. ET, Dow e-minis were down 25 points, or 0.07%. S&P 500 e-minis were up 0.25 points, or 0.01% and Nasdaq 100 e-minis were up 24.25 points, or 0.15%.Tesla – Tesla CEO Elon Musk sold another $973 million in Tesla stock to cover a tax bill generated by the exercise of options covering 2.1 million