ETH/BTC Ratio Mean-Reversion, Dollar-Neutral Long-Short (BINANCE USD-M Perps ETHUSDT + BTCUSDT, Daily Bars, Fade STATISTICALLY-EXTREME Dislocations of the log(ETH/BTC) Spread from its 60-Day Mean Back to Fair Value — Held Days-to-Weeks, Regime-Guarded Against Secular ETH-Season Trends, Pure OHLCV, 3-Parameter)

A DOLLAR-NEUTRAL, market-neutral pairs mean-reversion on the two DEEPEST crypto instruments — ETHUSDT and BTCUSDT USD-M perpetuals — trading the log(ETH/BTC) relative-value SPREAD, not either absolute price. The core insight: absolute crypto prices trend (which is why outright reversion mostly dies), but the ETH/BTC RATIO is a bounded, flow-driven relative-value series that mean-reverts around slow-moving levels — capital rotates between the two majors and overshoots, then snaps back. This is deliberately the OPPOSITE SIGN of the risk-rejected SOL/ETH spread-TREND follower (which rode the ratio and got rejected on risk): here we FADE extreme dislocations, entering only when the spread is statistically stretched (|z| > 2 vs its 60-day mean) and targeting reversion to fair value. It is engineered against the dominant killers: FEE_EDGE — entries are rare (only >2-sigma stretches) and each targets a large reversion (a 2-sigma ETH/BTC move is typically 4-8%), so the ~0.20% two-leg futures round-trip is dwarfed by the per-trade move (unlike the two-leg spot-perp CARRIES that just died because the spot leg's impact cost ate a sub-2bp funding edge — this trade has NO spot leg and captures a percent-scale relative move, not basis points); OVERFIT — three robust parameters (lookback, entry-z, stop-z), no per-name tuning; RISK — a secular-trend GUARD keeps it from fighting a sustained ETH-season/BTC-season, and a hard stop on further divergence bounds the classic pairs blow-up. It fills the most under-represented direction bucket (long_short 14.6% vs target, market_neutral) and the pairs scope, on pure OHLCV (the best-surviving data tag at 4%).