Cross-venue, market-neutral event trade. For each of 10 liquid alts (SOL, DOGE, XRP, LINK, AVAX, ADA, ETH, BNB, LTC, DOT), on every closed 1H bar compute two numbers. (a) Venue share = 24h base-unit volume on <COIN>USDT.BYBIT / (24h volume on <COIN>USDT.BYBIT + 24h volume on <COIN>USDT.BINANCE), z-scored against its own trailing 720-bar (30-day) mean and std. (b) Shock = 24h log return of the Bybit perp / (std of 1h log returns over 720 bars * sqrt(24)). When shock <= -shock_z AND share_z >= share_z_min, buy the Bybit alt perp at the next bar. At the same time, short BTCUSDT.BYBIT sized at beta * alt notional (beta = 720-bar hourly-return covariance / BTC variance, clipped to [0.3, 2.0]). Close both legs after hold_hours. One event per coin per hold window. Economic cause (a new claim, not a ticker swap): Bybit's flow is disproportionately retail and high-leverage. When a coin's selloff runs with an outsized Bybit share, the selling is liquidation or retail-panic flow, not informed repricing led by Binance. It overshoots the coin's own fair value and partly reverts within ~12-24h. The BTC hedge removes the market-wide crash-rebound part (on its own only Sharpe ~0.6) and keeps the coin-specific overshoot. POINT-IN-TIME PRE-STUDY (local catalog, 2021-10 to 2026-09, both venues' 1H bars, entry at next bar, 10% per alt leg, 0.22% two-leg RT cost): share_z>=1.0, shock<=-2.5, 12h clock gave 560 events, mean BTC-hedged residual +0.87% per event gross, calendar Sharpe 1.09, positive in 6/6 years. The 24h clock gave 400 events, +1.29%, Sharpe 1.02, positive in 5/6 years. CONTROL without the venue-share filter: Sharpe 0.55-0.63, so the Bybit-share condition is what lifts the edge. The unhedged long-only version only reached Sharpe 0.67-0.79 and was rejected. Fading upside shocks showed no edge and is excluded. Data: Bybit linear perp OHLCV (Bybit collector, 1H from 2021) plus Binance USD-M 1H OHLCV (Binance Vision), both confirmed present locally for all 10 coins and BTCUSDT.BYBIT. Universe capped at 10 names per L173. Per-bar work must use O(1) rolling updates.