DPI Spike (≥55%)
Off-exchange share above 55% means institutions are deliberately avoiding lit price discovery — often before a catalyst or while accumulating quietly. Combine with bid-lift bias for directional read.
Block Cluster
3+ blocks ≥$5M in the same direction within 60 minutes. That's an algo working a parent order. Direction (bid-lifted vs offer-down) tells you the side; you trade with it, not against.
Late-Day Surge
Disproportionate dark prints in the final 30 minutes (≥25% of day's blocks) signal next-day positioning. Often precedes a gap. Watch the bias — close-side surge with bid-lift = gap-up odds elevated.