I think this is just a normal correction within an ongoing bull market but I don't think it is over yet. The only remotely bullish sign is the drop to very oversold levels in the 10 day moving average of the number of advancing NYSE issues (top chart). But in the hourly chart of the cash S&P itself (second chart from bottom) you can see that the average still has a way to go before it reaches support provided by two recent tops (green lines) and an ascending trend line. My best guess now is that the average will drop to 1580 or so before the next leg up in the bull market begins.
There are two other indicators which can help identify the low when it occurs. The bottom chart shows the 5 day moving average of the CBOE put-call ratio. At the correction low I would expect this moving average to be above the descending green trend line and probably above its April high too. The second chart from the top shows the 20 day moving average of the daily count of the number of S&P issues which are trading above their 50 day moving averages. By the time the correction is over I would expect to see this indicator below its April 2013 low (blue line) and near the ascending trend line I have drawn.
Finally I should note that the 50 day moving average of the S&P is currently at 1604. During bull market corrections the S&P will typically drop below it 50 day moving average