Regime-Gated Daily Down-Shock Absorption on a Rule-Selected 40-Name BINANCE_SPOT Panel: buy a spot alt at the close of a <=-2.5-sigma, >=1-sigma-volume UTC day ONLY while BTC closes above its 200-day SMA, fixed 2-day clock, max 8 concurrent at 8% each (1-DAY, long-only cash, flat most of the time, entries from 2021-01-01)

Original Research Lead hypothesis. It pre-registers the NEW hypothesis that the analyst named when closing the OKX transfer of the daily down-shock absorption panel (run 7276bf13, closed underpowered: 397 trades, avg trade 0.97%, PF 1.41, but 2022 lost 12.4% and drawdown hit 23.2%). The analyst wrote: 'A regime filter (for example, skip entries when BTC is below its 200-day average) would be a NEW hypothesis to pre-register, not an amendment.' This run is that test. It moves to BINANCE_SPOT (10.4% of the corpus against a 15% target; spot-tagged runs survive best, L192), the correct venue for a long-only, unlevered idea. Binance spot also has deeper history than Hyperliquid, so the test window holds a full bear year (2022) and the 2026 drawdown. MECHANISM: a UTC day that closes with an unusually large drop on unusually high dollar volume is dominated by forced and impatient sellers: perp liquidations spilling into spot, stop cascades, de-risking. Price-insensitive selling pushes the close below where patient liquidity clears, and the buyer is paid by a partial rebound over the next 1-3 days. This is the long-side absorption design that L224/L230 record as working: Hyperliquid daily panel 7710f417 promoted (191 trades, 2.49%), Bybit spot 4H panel promoted (405 trades, 1.78%). The new element is the regime gate. In a sustained bear market, a down-shock is information (the next leg down), not a liquidity overshoot. That is exactly where the OKX transfer lost its money. The gate is the textbook 200-day SMA of BTC, fixed in advance. It is NOT searched. UNIVERSE (rule-based, point in time, includes later-delisted names): the 40 largest Binance spot USDT pairs by Q4-2020 (Oct-Dec) quote volume, among pairs listed on 2020-12-31. Excluded: BTC itself, stablecoins and fiat pairs, PAXG/WBTC, and leveraged UP/DOWN tokens. Result: ETH, XRP, LTC, LINK, BNB, YFI, BCH, ADA, GRT, XLM, EOS, DOT, UNI, TRX, YFII, SUSHI, VET, SXP, FIL, ZEC, ZIL, AAVE, ETC, XMR, DASH, NEO, THETA, CRV, ATOM, XTZ, WAVES, OMG, BAND, EGLD, ONT, NEAR, REN, RSR, SNX, ALGO. Several were later delisted from Binance spot (XMR, WAVES, OMG, REN, YFII and others); they stay in the universe. The base template's listing calendar closes a position at a delisting at the last price, and is_listed() blocks entries after it. Because membership is fixed with information as of end-2020, NO entries are allowed before 2021-01-01 (parameter trade_start). Every traded event therefore comes after the selection date, which removes the survivorship and look-ahead bias that a 'today's names' basket would carry. BTCUSDT.BINANCE_SPOT 1-DAY is a signal-only leg for the regime gate and is never traded. PRE-STUDY (Research Lead, local catalog BINANCE_SPOT 1-DAY, rolling stats from past bars only, entry at the signal close, 0.25% round trip charged = 0.20% fee + 0.05% slippage, non-overlapping per name, events from 2021-01-01). Frozen HL rules: shock_z <= -2.5, volume_z >= 1.0, 60-day lookback, 2-day clock. - Ungated: 740 events on 161 distinct entry dates, mean net +1.98%, median +1.44%, win 60%. By year: 2021 +2.3%, 2022 -3.83% (109 events), 2023 +2.05%, 2024 +2.83%, 2025 +7.65%, 2026 +2.21%. Capped portfolio (8 concurrent x 8%): 464 trades, +53%, Sharpe 0.65, max DD 26.1%. This reproduces the OKX failure mode. - Gated (BTC close > SMA200 at the signal close): 477 events on 99 distinct entry dates (L238: entry dates are the real sample, not trades), mean net +3.11%, median +2.01%, win 66%. By year: 2021 +2.19% (120), 2023 +2.04% (142), 2024 +2.77% (128), 2025 +8.26% (68), 2026 +0.72% (19). 2022 has zero gated events. Capped portfolio: 302 trades, +79%, Sharpe 1.00, max DD 7.0%. - The complementary BTC<SMA200 arm: 263 events, mean -0.06%, 3-day mean -1.24%. HONEST CAVEATS, disclosed because I saw them before writing this: (1) I looked at the gate split in the pre-study, so the gate is not blind. It was proposed by the analyst before this study, and its 200-day length is the textbook value, frozen and not tuned. (2) The gate costs money in 2026: most 2026 events fire with BTC below its SMA200, and those were positive (+2.61%). (3) 2025 carries about 38% of the gated pre-study profit. (4) Distinct entry dates are about 99 over 5.8 years, about 17 a year, so the evidence is moderate. LONG-ONLY DRAWDOWN COMPARISON (L170/L224): an equal-weight buy-and-hold of the same 40 names drew down more than 80% in 2021-22. The pre-registered limit for this panel is 15%. EXECUTION SUBSTITUTION (capability next_bar_open_fill = use_equivalent): entries and exits are market orders at the signal bar's close. On this 24/7 venue that price is the next bar's open. Spot CASH account: long-only, no leverage.