S&P 500 (SPY) 267.20 is the weekly chart breakdown it held for 15 months. If it can clear, we still have lots of resistance. If cannot clear, I suspect more sellers will appear.
Russell 2000 (IWM) 152 major overhead resistance. But, the longer it holds 144 the better.
Dow (DIA) 245.50 is the exponential MA that if it cannot clear most likely means selloff not over.
Nasdaq (QQQ) 158.00 is the weekly moving average that has not seen a week close below since November 2016. 155 pivotal.