Original Research Lead hypothesis (not seeded). An independent-venue replication of the promoted Bybit 'Thin-Liquidity Weekend Pump Reversal, BTC-Hedged' (198 trades, PF 1.23) on Hyperliquid, which is below its venue quota (14% vs >=20%) and whose only HL promotions so far are long-side down-shock panels; this adds the hedged SHORT side that L256 says is the only short-side shock design that has survived. MECHANISM: on Saturday/Sunday the institutional and market-making liquidity that arbitrages alt-vs-BTC mispricing is thinner, so retail-driven or narrative-driven weekend pumps in individual alts overshoot their BTC-explained move; when weekday liquidity returns (Monday-Tuesday) the idiosyncratic excess partially mean-reverts. The trigger is defined RELATIVE TO BTC and the trade carries a BTC hedge leg, as L256 requires (no raw-return trigger, no unhedged short). PRE-STUDY (frozen rule, measured by the Research Lead on catalog 1-DAY bars, 17 liquid HL names listed before 2021-06, BTC hedge, 2020-08..2026-10): x = ln(alt Mon00/Sat00) - ln(BTC Mon00/Sat00); sigma = std of that name's previous 26 weekend x values (min 20); z = x/sigma. Events with z >= 1.5: 318 pair-trades on 156 distinct Mondays; mean 2-day hedged forward return (short alt + long BTC, each leg equal dollars, measured as a fraction of the alt-leg notional) +0.94% gross, +0.76% net of 2 x 0.09% HL round trips, win rate 61%; by year mean 2.8% (2021), 0.0% (2022), 1.3% (2023), 0.6% (2024), 1.0% (2025), 0.4% (2026 YTD) - positive in 5 of 6 years. z>=1.0 gives 569 events at +0.52% net, z>=2.0 gives 208 at +0.91% net, so the effect is monotone in the threshold rather than a single cliff. The long mirror (z<=-1.5) was weaker (+0.55% net, 93 dates) and is NOT part of this hypothesis. Funding was not in the pre-study: the short alt leg during pumps usually RECEIVES positive funding and the BTC long pays it, so the net funding effect should be small; the backtest charges it via the funding ledger. EXECUTION: the decision is made on the close of the Sunday daily bar (stamped Monday 00:00 UTC); on this 24/7 venue a market order at that close is the next bar's open (the registry's use_equivalent for next_bar_open_fill - substitution named here). Data-coverage check per L237/L259: all 24 legs plus BTC have HL 1-DAY bars in the catalog from 2020-08..2021-01 (the 7 extra candidates are FTM, MATIC, MKR, SNX, COMP, RUNE, ATOM); funding is the only supplementary feed and is cost-only (not a signal), so a funding gap cannot remove events. Pre-registered event count inside the overlap: >=150 distinct event Mondays and >=300 alt-leg trades (measured 156 / 318 on the 17-name subset).