Inverse-Margin Deleveraging Flush on COIN-M: buy a Binance COIN-M alt inverse perp at the close of a <=-2-sigma UTC day ONLY when its own COIN-M contract open interest fell >=8% that day, fixed 3-day clock (47 point-in-time BINANCE_CM USD_PERPs, 1-DAY, long-only event panel, max 6 concurrent at 8%, flat most of the time)

Original Research Lead hypothesis. It tests forced-deleveraging capitulation on the venue where that forcing is structurally strongest: Binance COIN-M inverse perpetuals. A coin-margined long posts the same coin it is long as collateral. When price falls, the position and the collateral lose value together, so effective leverage rises convexly and liquidations cluster on COIN-M longs during down-shocks. COIN-M open interest is counted in USD-face contracts, so its daily change is a direct, price-orthogonal count of positions closed. A large contract-OI drop on a sharp down day therefore marks liquidation-driven selling that ran ahead of fundamentals. Liquidity providers who buy that flush should earn a short-horizon rebound (Nagel 2012 liquidity-provision returns, conditioned on a direct forced-selling marker, as the analyst asked in the OKX stress-day post-mortem of 2026-10-18). Relation to prior art. The promoted Binance SPOT deleveraging-confirmed capitulation panel (risk_review) conditioned spot alt down-shocks on the USD-M perp's OI drop. This is a separate venue and instrument-class test (lesson L228: a transfer is a fresh test, results reported separately). It trades the inverse contract itself, conditioned on that contract's own COIN-M OI from the BINANCE_CM Vision metrics feed (5-min, from 2021-07). CoinMAltPanelVolumeShockAbsorption1H (in pipeline) conditions on volume on 1H bars; this idea conditions on positioning on 1D bars. Pre-registered fixed-rule measurement (lessons L223/L237/L238), counted once by the Research Lead before writing this, with close-to-close 3-day forward log returns and no costs, for disclosure and the DSR ledger. Across 47 COIN-M USD_PERPs (BTC excluded), the rule z<=-2 AND OI change<=-8% fired 584 times on 109 DISTINCT dates from 2021-07 to 2026-10, mean +0.57% per event. The per-date mean is +0.34% (median +0.47%), and the per-date t is only 0.37 because events cluster: up to 36 names on one day, 29 dates with more than 6. The same z<=-2 down-shock WITHOUT the OI condition fired 1,957 times with mean -0.22%, so the incremental expectancy attributed to the OI-flush marker is about +0.8% per event (the lesson L217/L214 comparison). Year split of the conditioned events: 2021 +2.8% (66 events), 2022 -2.4% (236), 2023 -0.1% (112), 2024 +6.4% (53), 2025 +4.4% (84), 2026 +0.3% (33). The bear year 2022 (LUNA, FTX) is negative, so this is NOT a strong edge and the predictions below are modest. Effective evidence is roughly 109 entry dates, not 584 trades. Fee arithmetic. COIN-M taker is 0.05% per side, so 0.10% round trip, plus roughly 0.05% of funding paid by a long over 3 days (funding is often negative after a flush, which would be a credit). Gross capture is about 0.57% per event, so net is about 0.42% per trade: about 4x the round-trip cost. Execution. Decisions are made on the 1-DAY bar close (00:00 UTC). On this 24/7 venue a market order at the signal bar's close is the faithful equivalent of a next-bar-open fill (capability next_bar_open_fill = use_equivalent). Size inverse contracts in whole USD-face contracts with contracts_for_notional(). Universe, point in time: at each daily close the eligible set is every BINANCE_CM <BASE>USD_PERP in the instruments list that is listed at that bar (universe_at / is_listed, delisted names included until their delisting) and has at least 90 days of daily bars and of OI history. BTCUSD_PERP is excluded (the panel trades alts plus ETH). Risk profile (conservative). Route (b): a fixed time exit plus capped sizing. 8% of equity per leg, at most 6 concurrent legs (48% gross), 1x, no leverage. The intended strategy volatility is about 15-25% annualized, inside the 60% band. A single leg at 8% of a coin with about 100% annual vol contributes about 8% annualized vol, far under the 120% cap. The worst plausible single trade (-50% in 3 days) costs 4% of equity, under the 15% limit.