A stock market crash is a sudden, steep fall in stock prices, usually 10% or more in days, driven by panic selling. For traders, the right response is decided before it happens. Cap total risk, know your stops, and cut position size as volatility rises. During the crash, don't average down, don't trade against the move, and expect US circuit breakers to halt trading at 7%, 13% and 20% declines in the S&P 500.
Crashes are rare, but they're when accounts get destroyed, and also when some traders have their best months. The difference is almost never prediction. It's preparation: position sizing, a plan written in calm conditions, and the discipline to follow it.
Crash, correction or bear market?
| Term | Rough definition |
|---|---|
| Pullback | 5–10% decline from a recent high |
| Correction | 10–20% decline, often over weeks |
| Crash | Very fast, steep decline (often 10%+ in days, or a huge single-day drop) |
| Bear market | 20%+ decline from a high, usually over months |
Historic examples: Black Monday in October 1987 (the Dow fell 22.6% in one day), the 2008 financial crisis, the May 2010 flash crash, and the February–March 2020 COVID crash, when the S&P 500 fell about 34% in roughly a month.
How US circuit breakers work
Market-wide circuit breakers pause trading when the S&P 500 falls sharply from the prior day's close:
| Level | S&P 500 decline | What happens |
|---|---|---|
| Level 1 | 7% | 15-minute trading halt (if before 3:25 p.m. ET) |
| Level 2 | 13% | Another 15-minute halt (if before 3:25 p.m. ET) |
| Level 3 | 20% | Trading halted for the rest of the day |
Individual stocks also have Limit Up–Limit Down (LULD) bands that pause single names moving too fast. Index futures have their own price limits overnight. In a crash, expect halts, gaps and slow order handling, and understand that stop orders don't guarantee your price.
Score the Setup Before You Take It
TRADZY's Void Engine rates any setup 0–100 across 12+ variables: structure, trend alignment, volume, momentum and key levels.
Score a Setup Free →Before: the only time you can really prepare
- Know your total open risk. Add up what you'd lose if every open position hit its stop at the same time. In a crash, correlations jump toward 1, so diversification across stocks stops helping. See correlation risk.
- Keep leverage modest. Margin calls force you to sell at the worst prices. Most blown accounts in crashes are leveraged accounts.
- Write a crash plan in calm conditions: at what VIX level or index drawdown you cut size, which positions you close first, and when you stop trading for the day.
- Hedge if appropriate. Longer-term holders may use index puts or reduce exposure. Hedges cost money and work best when bought before volatility spikes.
- Have a daily and weekly loss limit. The worst damage in crashes usually comes from traders trying to win back losses. Max drawdown explained shows why recovering from large losses is so hard.
During: rules for the worst days
- Cut size. When the VIX doubles, typical daily ranges roughly double too. Halving position size keeps your dollar risk about the same.
- Don't average down. Adding to losing longs "because it's cheap" is how a 10% loss becomes a 40% loss.
- Don't catch knives. Wait for structure, such as a higher low on the intraday chart or a reclaim of VWAP or the prior day's low, before trying a long.
- Respect the gaps. Overnight risk is extreme. Consider flattening before the close.
- Shorting isn't free money. Crashes produce violent short-covering rallies of 5–10% in index terms. Short-sellers get squeezed as often as buyers get trapped.
- Stop when your limit is hit. Volatility produces fast wins and fast losses. The daily loss limit matters more on these days, not less.
After: the recovery phase
Crashes often end with a capitulation day (huge volume, extreme VIX, most stocks at lows) followed by a sharp rebound. What usually follows is a volatile base, not a straight line up.
- Scale back in gradually, starting with small size and relative-strength leaders: stocks that fell least and recovered first.
- Watch breadth. A recovery led by many stocks is healthier than one led by a few.
- Review your journal. Which rules did you follow? Where did you break them? Crashes are the best stress test your process will ever get.
The mistakes that actually blow accounts
| Mistake | Why it's deadly |
|---|---|
| Too much leverage | Forced liquidation at the lows |
| Averaging down | Turns one loss into a concentrated position |
| No stops, or moving them | Small losses become catastrophic |
| Revenge trading | Oversized trades after losses, in the most volatile conditions |
| Selling long-term holdings at the bottom | Locks in losses that often recover |
If you're not sure what's driving a sell-off in the first place, run the checklist in Why Is the Stock Market Down Today?
TRADZY's analytics track your drawdown and daily loss in real time, so your crash plan's limits are visible when you need them, not just written in a notebook.
FAQ
What causes a stock market crash?
Usually a trigger, such as a financial shock, a pandemic or a policy surprise, hitting a market that's already stretched: high valuations, heavy leverage and crowded positioning. Forced selling then feeds on itself.
What happens to my stocks if the market crashes?
Their prices fall, often together, but you still own the shares. Losses become permanent if you sell or get margin-called at the lows. Companies that survive usually recover over time, but individual stocks can fail.
Should I sell everything before a crash?
Nobody can time crashes reliably. It's better to manage exposure continuously: keep leverage modest, cap total risk, cut size when volatility rises, and follow predefined stops.
How long do stock market crashes last?
The sharp phase often lasts days to weeks. Full recovery to previous highs has ranged from months (2020) to years (2000 and 2008).
Do circuit breakers stop crashes?
They pause trading to slow panic and give time to process information. They don't stop prices falling once trading resumes.
Put This Into Practice
- Score your next setup 0–100 with the Void Engine before entering
- Log the trade and tag the setup in the TradLog
- Review weekly: keep what pays, cut what doesn't
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Educational content, not financial advice. Trading involves substantial risk of loss.