A strategy that works in one regime often fails in another. Bull and bear markets are not just different return environments; they produce different microstructure, volatility, and liquidity behavior.

Why single-regime success is misleading

If your best period dominates total return, your strategy may be regime-dependent. That is acceptable only if you explicitly run it as a conditional strategy with clear activation rules.

Regime test framework

Use a simple four-step structure:

Segment history into regime buckets (bull, bear, high-vol range, low-vol range).
Evaluate performance and drawdown per bucket.
Run walk-forward windows crossing regime boundaries.
Stress costs and slippage more in adverse regimes.

Without boundary-crossing tests, you miss many failure modes.

Metrics to compare by regime

Net edge after costs
Max drawdown and recovery speed
Trade frequency stability
Win/loss distribution shape
OOS retention and WFE behavior

Look for stable risk-adjusted behavior, not identical returns.

Typical warning signs

Positive returns only in one directional regime.
Drawdown spikes when volatility transitions.
Trade logic overreacts in chop but underreacts in trends.
Cost drag doubles in adverse phases.

If two or more warnings appear, reduce confidence and size.

Deployment implications

If regime dependence is high:

lower allocation,
require regime filters,
tighten kill-switch thresholds,
schedule more frequent re-validation.

A strategy can still be useful, but only with explicit regime-aware risk controls.

Handoffs matter: test the transition weeks

Many failures happen in the first weeks after a regime flip, when models lag and liquidity shifts.

Tag performance around transition windows explicitly, not only inside stable bull or bear buckets.

Crypto-specific: include funding and basis stress

For perpetuals, regime tests that ignore funding can label a strategy "fine" while live carry drags it negative (Walk-forward for mean reversion).

Do not confuse correlation with causation in labels

Simple bull/bear labels are operational, not truth.

Use them to stress the strategy and to communicate risk, not to claim you "predicted" regimes.