 U.S. stock markets look to have a slight negative bias as we approach this morning's opening bell and following yesterday's session, which saw the S&P 500 at a bit above 1% to breach the 5600 level for the first time in history, while the tech-laden Nasdaq index was the relative outperformer of the three major averages, posting an almost 1.2% advance to close at yet another all-time high.