Very typical 'W' pattern forming on 2h with a 'handle' on the end of the W. This projection would go to about 4400 on SPX500 , probabaly before the end of June. We have a nicely confirming MACD and RSI making higher lows through this construction. We also have very long shadows on the W bounce points (see circled lows) meaning the buyers were extremely aggressive buying at this trendline - I.e. "buy the dip" folks are being very aggressive on dips! Any closing under 4180 is caution; under 4160 would be reversal zone (I.e. not looking at new ATH's!) Otherwise it looks like we are getting close to an explosive upward move.
Other interesting things to consider: bond yields have been falling, the dollar is weak (and sitting on support; aggressive upside movement could be a problem for asset prices), and relative laggards in tech could wake up and propel things higher at any time (AMZN, GOOG, AAPL, MSFT in particular)