On VIX>28 days the SPY intraday range medians 2.20% and QQQ 2.73% — 3x calm-tape behaviour. We don't trade risk-off by cutting size; we reprice volatility, ETF volume, and quote stability and let those decide the route.

Across 5,365 sessions on SPY/QQQ/NVDA/TSLA/AMD, exhaustion-close rate climbs from 27% on calm-volume days to 49% at 1.8-2.5x volume. High relative volume is participation, not sponsorship — and order flow shows which we're looking at.

Dark pools are not a magic edge. FINRA data shows off-exchange flow splits between ATS dark venues and non-ATS wholesalers, and the mix is symbol-specific. The desk routes dark only when footprint or midpoint interaction beats immediacy.

Zero commission isn't zero execution cost. Modeled 1-3 bp per-side drag erases a meaningful share of a 1-min range in liquid ETFs. Rule 605/606 disclosures expose the pattern but not the per-trader cost. Measure implementation shortfall.

Liquidity packets — bursts of participation that reveal accumulation or exhaustion before the candle confirms. CVD slope, refresh behavior at price levels, and trade-size distribution separate accumulation packets from exhaustion packets. The chart looks similar; the order flow doesn't.