Quant Memo

Regime Detection

Identifying and adapting to different market states (trending vs mean-reverting, risk-on vs risk-off).

Definition

Regime detection aims to classify the current market state (e.g. trending, mean-reverting, high vol, risk-off) and optionally switch or weight strategies accordingly.

Why it matters

  • Many strategies work in one regime and fail in another (e.g. mean reversion in trends).
  • Adapting or reducing exposure in bad regimes can improve risk-adjusted returns.

Common approaches

  • Vol regime (high vs low vol), trend strength (ADX, moving average slope), correlation regime, macro indicators.
  • Often used as a filter: only run strategy X when regime = Y.

Common mistakes

  • Regime model itself overfitted.
  • Lag in detection (regime identified after the move).
  • Over-relying on one regime indicator.

Linked strategies

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