Big buy imbalance late (15:55+)

Price typically gets pushed up into the close. Next-day open often retraces 30-50% — fade if no overnight catalyst.

Index rebalance day

Quarterly Russell/S&P reconstitution = massive MOC. Pre-position 1-2 days ahead; expect mean-revert after.

Persistent sell imbalance

If sell imbalance persists 15:50–16:00, that's real distribution. Avoid catching falling knives next-day.