This is a zoomed in 15m chart, but these levels go back starting in May. That's where the trendline began that we broke below and could retest soon. In addition to that trendline, we would also have the 555 level that should be near the area where we retest the trendline if it happens. SPY still has a ways to go and one important level to break before it gets there, but it should be a good opportunity if it does.
It can work for a long too. If we're able to break back above the trendline and 555, I'd be looking for longs on a retest.