Beware the near term price action! You need to wait for the monthly close to confirm a proper breakout, the shorter term picture could be more tricky to play!
The reason why I expect a breakout at least in the near term is pretty simple, the price is really strong and really stretched therefore it calls for small hands to come in and take the short side of the trade in the hope to time the perfect low risk entry.
This is what makes me tick, the "low risk entry" or in other words tight stops easy to hunt. Knowing where stops are placed gives a significant edge (and incentive ultimately) to big hands to push the S&P a tad higher, yes just to kick out the small players.
As we are in a long term monthly time frame, in case the breakout happens there is still a window of 15 days left to confirm it. Don't forget that in case the monthly closes below the resistance line it could be interpreted as a medium/long term reversal signal.
PS: For a quick in and out short term reversal play better wait for the annoying and so common "S&P hit fresh record high" to be released in the media or for the famous "reversal Tuesday" before taking the trade.