The S&P 500 is having a solid rally today on light volume. At this very moment the $SPY (the tracking ETF for the S&P 500) is filling a major gap from May 2nd, 2016. In addition, it is tagging a downsloping trend line that starts on April 20th, 2016.
Note the chart below. This should be significant resistance for the markets. Look for a possible pull back off this level.