Since the Oct lows the SPX, on average, took 4 days to rally 12%, 8.5%, 19%, 11%, 8% and 8.5% from each sizable retreat.
Since Feb 9 the SPX has retreated 19.5% with no real rally. Unless the world really is ending, I expect a 10-15% rally in the next few days.
A larger rally, say 20%...