SPY is showing signs it is ready for a boom. Compared to GOOG, AMZN, AAPL it is underperforming. SPY is neither overbought nor oversold which is a good thing. PLEASE COMMENT WHAT YOU THINK!
In order for SPY to "boom" you have to have the participation of the broader market. XLF in particular. The big cap tech stocks you mentioned are already overbought so the next leg would have to be outside of growth stocks.