Hyperliquid Idiosyncratic Down-Shock Rebound, BTC-Beta-Hedged: long the HL alt perp + short beta-weighted BTCUSD.HYPERLIQUID after a <=-2.5-sigma BTC-residual 24h drop, fixed 12h clock (18 HL perps, 4-HOUR, market-neutral event panel, flat most of the time)

Original Research Lead hypothesis. This is a fresh venue test (L228) of the BTC-beta-hedged idiosyncratic-selloff rebound. That family was promoted on Binance USD-M (spot-led variant: 374 trades, avg 0.61%) and on Bybit (retail venue-share variant: 598 trades, avg 0.62%). Here it trades entirely on HYPERLIQUID, which holds 13.3% of the corpus against a 20% target. The design is long-short and market-neutral, so it also adds to the under-represented long_short bucket (24%). Mechanism: when one alt falls far more over 24h than its BTC beta explains, the excess selling is coin-specific forced or impatient flow, for example HL cross-margin liquidations, auto-deleveraging and stop cascades on a thin book. Price-insensitive sellers push the alt below the level where discretionary liquidity clears, and over the next half day it partly recovers RELATIVE TO BTC. Shorting beta x BTC removes the market factor, which is what made the unhedged OKX market-shock version underpowered: it was exposed to the 2022 bear regime. SIGNAL (computed on every closed 4H bar, from past data only): beta = OLS beta of the alt's 4H log returns on BTCUSD.HYPERLIQUID 4H log returns over the last lookback_bars (baseline 180 bars = 30 days), clipped to [0.3, 2.0] and lagged one bar. Residual 24h move: r_res = ln(alt_t / alt_t-6) - beta * ln(btc_t / btc_t-6). sigma_res = std of 4H residual returns (r_alt - beta*r_btc) over lookback_bars, lagged 6 bars so the shock itself is excluded. z_res = r_res / (sigma_res * sqrt(6)). PRE-STUDY (Research Lead, point-in-time, local catalog HL 4-HOUR, 2024-03 to 2026-08, 18 names, one event per coin per hold window, entry at the signal close, net of 0.09% x (1 + beta) round trip on both legs): z_res <= -2.5 with a 12h clock gave 481 events on 164 DISTINCT event days. Mean hedged net was +0.52% per event (median +0.38%, t 3.0). The unhedged alt leg alone averaged +0.80%. By year: 2024 +0.73% (179), 2025 +0.77% (169), 2026 -0.07% (133). 2026 is flat, and that is the main honest risk. The 24h clock gave +0.50% (366 events). z <= -3.0 gave +0.83% (247 events, 76 distinct days). Using the TOTAL (not residual) 24h shock gives higher means but concentrates on only 67 distinct market-crash days, so the residual trigger was chosen for independence (L238: count distinct dates, not per-name trades). A tested and REJECTED filter, named here: requiring Hyperliquid's share of HL+Binance volume to be elevated (Bybit-style venue-share condition) was non-monotone. With share_z >= 1 the result was +0.26% (230 events); with share_z >= 0 it was +0.73%; with share_z < 0 it was 0.00%. That pattern looks like noise, not a mechanism, so the venue-share condition is excluded and no Binance data is used. No short (fade-the-pump) arm: L230, and the Bybit sibling found no upside edge. DATA OVERLAP (L237): every leg (18 alts + BTC) has HL 4H bars from about 2024-01 (HL serves the last ~5000 4H candles, about 2.3-2.7 years). Inside that overlap the pre-study counted 481 events on 164 distinct days, well above the ~30 floor. EXECUTION: decisions are made on the 4H close. On this 24/7 venue the next-bar-open fill (capability next_bar_open_fill = use_equivalent) is a market order at the signal bar's close; this substitution is stated here. Netting accounts: all open events share ONE BTCUSD.HYPERLIQUID position, so the BTC hedge is the NET sum of beta_i x notional_i over the open alt legs. It is re-sized at each alt entry and exit. No hedge mode is needed. Risk route (b): fixed time exit plus capped sizing, no position above 100% of equity.