How Long A Stress Regime Lasts

Detecting that markets have entered a stress regime is only half the problem, knowing roughly how long that regime tends to persist changes what you should actually do about it. A strategy that de-risks hard on day one of every stress signal, expecting a multi-month regime, will sit out most of a one-day flash event's recovery; a strategy that waits a week to react, expecting a quick bounce, will get run over by a genuine multi-quarter deleveraging.

In practice, stress regimes cluster into a few rough durations. Liquidity flash events (a single-session crash or a flash rally reversal) typically resolve within hours to a few days as market makers step back in. Volatility spikes tied to a specific catalyst, an earnings shock, a surprise policy move, usually decay over one to three weeks as the news gets digested and priced in. Genuine macro stress regimes, a credit crunch, a recession scare, a sustained deleveraging, commonly run for two to six months and sometimes much longer, because they're driven by slow-moving forces like credit availability and balance-sheet repair rather than a single information event.

Because these durations differ by roughly two orders of magnitude, the practical rule is to size a response to the type of stress signal observed, not just its presence, a spike in intraday realized volatility calls for a different, faster-unwinding response than a widening in credit spreads or a persistent rise in cross-asset correlation, which tend to signal the slower-moving kind of regime.