Whatever precipitated the 20 point pullback was likely a result of a short term , known resistance or a secondary . And the that drove the market up and then down was miserably thin.
After hours half of the losses were recovered.
All of that said, the market remains "risk on" with high yield bonds moving up, high beta stocks outperforming the broader indices and small caps outperforming. And market internals are by no means stretched, suggesting further gains are likely
In looking at daily daily data I see no dominant pattern beyond a trend up but the hourly data suggests a possible five wave move up to, say, 2108.
Interesting read: http://www.marketwatch.com/story/dont-fall-in-love-with-the-market-rally-ahead-of-brexit-vote-analysts-warn-2016-06-20