What is a Stock Market Crash: Understanding the Sell-Off

A stock market crash is a sudden, severe fall in share prices across most of a market, usually measured on a broad index. A correction is typically a slower drop of 10% or more from a recent peak, while a crash is faster and deeper and can push a market through correction territory straight into a bear market. No regulator sets an official threshold for a crash, but the best-known examples are easy to measure: the Dow Jones Industrial Average fell 22.6% in a single session on 19 October 1987, and the S&P 500 lost 33.9% in 23 trading days between 19 February and 23 March 2020.

Does the market recover, or keep falling? Both have happened: recoveries have taken anywhere from about six months to 25 years, and some crashes were followed by further falls. What traders can read from a crash is less about timing and more about structure: how fast prices fell, how far, and what is limiting the selling. Because a CFD can be opened in either direction, a falling market is one traders can still take a view on or hedge against. It is also one where leverage magnifies losses.

Key takeaways

• A crash has no official definition. It is shorthand for a rapid, steep fall, while a correction (10% or more from a recent peak) and a bear market (20% or more) have commonly used thresholds. A crash can pass through both within weeks, as the S&P 500 did in 2020.
• Crashes tend to come from a mix of stretched valuations, borrowed money, panic and a trigger such as an economic shock or a collapse in liquidity.
• During a crash, the decisions a trader controls are the ones that matter most: avoiding forced sales, checking margin and not adding leverage to recover losses.
• CFDs allow trading in both directions and can be used to hedge a portfolio, but they are leveraged products that can lose more than the amount deposited. Short selling with CFDs is a high-risk, advanced strategy that is not suitable for everyone.

What is a stock market crash?

A stock market crash is a rapid and steep decline in the prices of shares across a large part of a market, usually driven by panic selling rather than by a gradual change in company fundamentals. It is different from a fall in one company’s share price, which can happen for reasons specific to that business.

There is no single official definition. Unlike a bear market, which the US Securities and Exchange Commission’s Investor.gov glossary describes as a fall of 20% or more in a broad index over at least a two-month period, a crash has no agreed percentage or time limit. In practice the word is used for falls that are both deep and fast, often double-digit percentage losses in a few days, and often for single sessions that stand out in market history.

That is why labels differ: the 1987 collapse took place in hours and is called a crash, while the far larger 2000 to 2002 technology slump unfolded over more than two years and is called a bear market.

What causes a stock market crash?

Crashes rarely have a single cause. Historians and regulators usually find several conditions already in place, then a trigger that turned worry into selling.

• Bubbles and stretched valuations. FINRA describes a bubble as prices climbing to levels that appear inexplicably high before they eventually fall. The Dow rose six-fold from 63 in August 1921 to 381 in September 1929, according to the Federal Reserve. The debate over whether new themes have stretched valuations, such as an AI bubble in the stock market, continues, but a high valuation alone does not set the timing of a fall.
• Leverage and margin calls. In the 1920s, buyers typically put down about 10% of the price of shares and borrowed the rest, so falling prices triggered demands for more collateral and forced sales. The same mechanism exists today: FINRA explains that when securities bought on margin fall by more than a certain amount, a firm can issue a margin call and, if it is not met, force the sale of the investor’s holdings, sometimes without notice.
• Panic and herd behaviour. FINRA defines panic selling as offloading large amounts of shares without necessarily working out whether selling is the wisest move, and notes that it can become self-fulfilling. On 19 October 1987, the Federal Reserve records that sell orders vastly outnumbered willing buyers near previous prices.
• Economic shocks and policy. Ahead of Black Monday, a larger-than-expected US trade deficit was reported and the dollar fell. In 1929, the Federal Reserve’s rate rises had unintended effects: because the gold standard linked currencies, foreign central banks had to raise their own rates too.
• Automated selling and thin liquidity. Portfolio insurance, which relied on options and derivatives, accelerated the 1987 fall because initial losses led to further rounds of selling. On 6 May 2010, the SEC described a sudden evaporation of meaningful prices for many exchange-listed shares in the middle of a trading day.
• Sudden external shocks. A pandemic, a war or a banking failure can change the outlook faster than forecasts adjust. The March 2020 fall followed the spread of COVID-19, and the September 2008 bankruptcy of Lehman Brothers came after losses on mortgage-related assets had strained markets for more than a year.

What is the impact of a stock market crash?

• On investors and retirement savings. The damage depends on timing. An investor with decades ahead has time for markets to recover, while someone close to retirement can be forced to sell at depressed prices, and margin calls can turn a temporary fall into a permanent loss.
• On the economy and credit. Falling share prices reduce household wealth, and fear reduces spending. Not every crash leads to a recession: the 1987 collapse did not, while the 2007 to 2009 fall coincided with an 18-month recession.
• On global markets. Markets are connected through trade and through funds that sell in one market to meet losses in another. In 2020 the pandemic hit every major market at once.
• On companies. Falling share prices raise the cost of raising money through new share issues, and heavily indebted businesses can face refinancing problems. Financial firms can sit at the centre of the problem: in September 2008 Lehman Brothers filed for bankruptcy, and the next day the Federal Reserve provided support to the insurer AIG.

How do markets protect themselves during a crash?

Black Monday led to a number of reforms, including rules that let exchanges pause trading during rapid sell-offs, according to the Federal Reserve. Today the US has two main protections.

Market-wide circuit breakers

The SEC’s Investor.gov explains that trading across US stock and futures markets can be halted when the S&P 500 falls by 7% (Level 1), 13% (Level 2), or 20% (Level 3) from the previous day’s close. A Level 1 or Level 2 breach before 3:25 p.m. Eastern Time halts trading for 15 minutes. A Level 3 breach at any time stops trading for the rest of the day. A Level 1 or Level 2 drop at or after 3:25 p.m. does not halt trading.

Limit up and limit down bands

For individual shares, the SEC describes a price band set around the average price of the previous five minutes. If the price reaches the edge of the band and does not move back within 15 seconds, trading in that share pauses for five minutes.

These tools slow the pace of selling and give investors time to take stock. They do not stop prices from falling, and they do not guarantee that a crash is avoided. On 6 May 2010 the Dow fell 9.16% below the previous close at its low and recovered much of it within minutes, but the fall was not enough to trigger a circuit breaker, according to the SEC. In March 2020 the market-wide halts did not prevent the S&P 500 from continuing lower afterwards.

What to watch after the halts

• Orderly or disorderly. A steady decline with working markets is different from one where prices gap and liquidity vanishes, as on 6 May 2010, when trading costs and slippage rise.
• Which line the fall reaches. Whether a fall stalls inside correction territory or crosses 20% is the clearest read on whether it is turning into a bear market.
• The official response. Federal Reserve statements and support were part of the response in both 1987 and 2008, so central bank and regulator announcements are worth following.
• Rebounds and retests. A sharp rebound is not proof that the fall is over. In March 2020 the S&P 500 made a lower closing low within ten days of a rally of more than 9% in a single session.

How traders proceed after a stock market crash

After the fall comes the second decision point: deciding what to do when prices are low, nerves are frayed and the future looks uncertain.

Review before re-entering

Check what happened and why. Did the losses come from market-wide falls or from concentration in one theme? Which decisions were forced by leverage or lack of cash, and which were voluntary? A crash is often the first real test of how much loss someone can tolerate, and if it was more stressful than expected, the portfolio may be riskier than it should be. Recoveries are uneven, and nobody can identify the bottom in real time.

Trading a correction market

A correction is a fall of 10% or more from a recent peak that has not reached 20%. After a sharp fall, prices often retrace part of the drop before resuming or reversing, as when the Dow regained 57% of its Black Monday loss within two sessions. Traders commonly watch whether the previous low holds and whether rallies stall where prices broke down. Because swings are larger and spreads wider than usual, a position sized for calm markets can be too big. Many traders reduce size and set a stop-loss before entering, and either direction remains possible, while accepting that a correction can end, deepen into something larger or reverse at any moment.

When a correction becomes a bear market

A bear market is a fall of 20% or more in a broad index over at least two months. The 2022 bear market took about nine months and the 2000 to 2002 bear market more than two and a half years. These are slow, grinding declines with rallies inside them, and a position held for weeks or months picks up overnight financing charges along the way. A bear market also changes what the main risk is: less the single-day gap of a crash and more the cost and drift of being wrong for a long time.

Managing leverage and exposure

As a fall extends, the risk factors that matter most are the ones traders control:

• Leverage. The higher the leverage, the smaller the adverse move needed to trigger a margin call. Using less of the available leverage leaves a larger buffer before positions are closed.
• Total exposure. Positions in several indices or shares can look diversified but often fall together in a crash. Add up the combined exposure across all open positions, not each one separately.
• Risk per position. Deciding in advance the most to lose on one position, as a small, fixed share of the account, keeps one bad trade from deciding the outcome.
• Margin level. Monitor it regularly. A deposit that cannot absorb a further fall is a reason to reduce size, not to add more leverage.

Rebalancing and dollar-cost averaging

For longer-term investors, rebalancing means returning a portfolio to its target mix of assets, which after a fall in shares can mean buying shares to restore the target weighting. Dollar-cost averaging means investing a fixed amount at regular intervals rather than a lump sum. Both are rule-based approaches rather than market-timing calls. Neither prevents losses or guarantees a gain, and whether either is appropriate depends on personal circumstances.

Crash, correction and bear market: what is the difference?

The three terms describe falls of different size and speed. The thresholds come from the SEC and FINRA.

The categories overlap. A crash can push an index straight through correction territory into a bear market, as happened in 2020. A bear market can contain a crash, and many corrections end without ever becoming anything larger. VT Markets compares the conditions on either side of a bear market in its guide to bear and bull markets.

Stock market crashes in history: corrections, bear markets and crashes

Seven episodes show the range, from a correction that stopped just short of a bear market to the deepest fall on record. Each is measured on closing levels of price indices, which exclude dividends.

A correction: 2018

From 20 September to 24 December 2018 the S&P 500 fell 19.8% over 95 days, just short of the 20% bear market line. It was deep enough to be unsettling but slow enough that no single day defined it, and it did not become anything larger.

A bear market: 2022

From 3 January to 12 October 2022 the S&P 500 fell 25.4% over about nine months. No single session defined it; the fall crossed the 20% line gradually, which is what separates a bear market from a crash.

A crash: 1987 and 2020

The Dow lost 508 points, or 22.6%, on 19 October 1987, which the Federal Reserve describes as the largest one-day stock market decline in history. Unlike 1929, it was not followed by a recession or a banking crisis: the Dow regained 288 points, or 57%, of the loss in two sessions and its pre-crash high in less than two years.

The S&P 500 closed at 3,386.15 on 19 February 2020 and at 2,237.40 on 23 March, passing through both the correction and bear market thresholds in 23 trading days. Daily moves were extreme: the index fell 9.51% on 12 March, rose 9.29% on 13 March and fell 11.98% on 16 March, and US stock markets halted trading four times under the market-wide circuit breaker rules, according to the Federal Register. The S&P 500 closed above its February high on 18 August 2020. The recession lasted only two months (NBER, February to April 2020), but US unemployment rose from 3.5% to 14.8%.

The extreme end: 1929, 2000 and 2007

In 1929 the Dow fell nearly 13% on Black Monday, 28 October, and nearly 12% the next day, according to the Federal Reserve, and did not close above its 1929 high until 23 November 1954. The Federal Reserve notes that problems in another part of the financial system turned what might have been a short, sharp recession into the longest, deepest depression the country had known.

The Nasdaq Composite lost 77.9% between March 2000 and October 2002 as internet valuations collapsed, and did not close above its 2000 high until 23 April 2015. The S&P 500 fell 56.8% between October 2007 and March 2009, after US house prices more than doubled between 1998 and 2006, and closed above its 2007 high on 28 March 2013. US unemployment peaked at 10.0% in October 2009.

Trading a falling market with CFDs

A share investor generally gains only when prices rise, unless they borrow shares to sell short. A contract for difference can be opened as a sell position without borrowing anything, which is why traders who understand CFDs can treat a crash as a market they can still trade, hedge or sit out, rather than one they can only wait through.

Using CFDs to your advantage

Hedging means taking a position that offsets a possible loss somewhere else. FINRA describes it as making investments intended to offset possible losses, to mitigate risk. An investor with a portfolio of shares who is worried about a market fall could open a short index CFD position that gains if the market drops, which would offset part of the loss on the portfolio. The mechanics, and the practical limits, are explained in a guide to hedging a share portfolio with index CFDs.

A hedge doesn’t need to be perfect to be useful. Even an imperfect hedge can soften the impact of a falling market, which gives investors more room to stay calm and stick to their plan. It does come with trade-offs: the index may not move exactly in line with the portfolio, the hedge has its own costs, and if markets rise, the hedge will lose money while the portfolio gains. Hedging reduces risk rather than removing it, and one of the most common ways to build a hedge is by going short.

How going short works in CFD

Going short means opening a position that gains when a price falls. With a contract for difference (CFD), a trader can open a sell position without owning the underlying asset and close it later with a corresponding buy trade. Unlike spot selling, this does not involve disposing of an asset the trader owns. In a CFD, it is simply how a short position is opened, and no asset changes hands. Going long is the reverse: a buy position that gains if the price rises.

For example, if an index trades at 20,000 and a trader sells one contract at USD 1 per point, a fall to 19,000 gains USD 1,000 before costs, while a rise to 21,000 loses USD 1,000. The figures are for illustration only, and contract sizes, margin and costs differ by provider.

A short position can lose more the higher a price rises.

Learn more in VT Markets’ guides on long and short CFD strategies and short selling.

Reading a falling market

A downtrend is usually identified by a series of lower highs and lower lows: each rally fails below the previous peak, and each sell-off goes lower than the last. Traders who short a falling market commonly mark the most recent peak and place a stop-loss order just above it, so the position closes if the trend breaks. That distance sets the position size for a given acceptable loss: the wider the stop, the smaller the position. In a crash prices swing widely and stops need more room, which points to smaller positions, not larger ones.

Common mistakes during market crashes

• Selling everything at the bottom. Panic selling after a large fall locks in losses and risks missing the recovery, whose timing nobody knows.
• Trying to time the exact low. Even professionals struggle to call the turn, and rallies inside a falling market can mislead.
• Using too much leverage. Borrowed money forces sales when prices are lowest.
• Concentration. Holding most wealth in one share, sector or theme means no cushion.
• Ignoring costs. Spreads, financing charges and slippage rise in volatile markets and can erode small positions.
• Revenge trading. Raising position sizes to recover a loss is a common route to a larger one.
• Assuming history will repeat exactly. Every crash has had different causes and a different recovery path.

A VT Markets demo account gives 90 days of practice, a way to experience fast price moves, margin and stop-losses without risking capital.

A stock market crash has no official definition, but the pattern repeats: stretched valuations, borrowed money and a trigger turn into panic, and prices fall faster than most investors expect. The history from 1929 to 2020 shows that falls of a third or more can happen within weeks, that recoveries can take anywhere from months to decades, and that no two crashes have had exactly the same cause.

What traders can control is structure, not timing. A written plan, position sizes that can be held through a drop and a clear view of leverage and exposure do more for resilience than any attempt to predict the next fall. CFDs give traders tools for falling markets, including going short and hedging, but they magnify losses as well as gains and are not suitable for everyone.

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Volatile markets put preparation ahead of prediction. Practise on a demo account, learn how leverage, margin and stop-losses behave, and decide in advance how much risk you are willing to take. VT Markets provides CFDs on forex, indices, precious metals, shares and more. Trading leveraged products carries a high risk of loss, and losses can exceed your deposit.

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Frequently asked questions

Can a stock market crash happen again?

Yes. Every era has had its own crash, and the causes have differed each time, from margin loans in 1929 to automated selling in 1987 and 2010 and a pandemic in 2020. Circuit breakers, margin rules and central bank liquidity support have been added since, but no rule can remove the possibility of a sharp fall.

How long does it take markets to recover from a crash?

It varies widely: about six months for the S&P 500 after 2020, less than two years for the Dow after 1987, about five and a half years for the S&P 500 after 2007, about 15 years for the Nasdaq Composite after 2000 and 25 years for the Dow after 1929. Index levels exclude dividends, so total returns for investors who reinvested them recovered earlier.

What is the difference between a crash and a correction?

A correction is a fall of 10% or more from a recent peak, usually unfolding over weeks to months. A crash is a sudden, severe fall, often with double-digit losses within days, and it has no official threshold. A crash can push a market through correction territory straight into a bear market, which is a fall of 20% or more.

Is a stock market crash the same as a recession?

No. A crash is a fall in share prices, while a recession, as the NBER describes it, is a contraction in economic activity. They can occur together, as in 2007 to 2009, but the 1987 crash was not followed by a recession.

Should I sell during a crash?

That depends on personal circumstances, and general information cannot answer it for any one person. Investors with a long time horizon often find that selling in a panic locks in losses, while those who need money soon may be forced to sell. A plan, made in calm conditions and reviewed with an independent adviser where necessary, is a more reliable basis for the decision.

What is a circuit breaker?

A circuit breaker is a rule that pauses trading after a rapid fall. In the US, market-wide halts are triggered when the S&P 500 drops 7%, 13% or 20% from the previous close: the first two halt trading for 15 minutes before 3:25 p.m. Eastern Time, and a 20% drop halts it for the rest of the day.

Can you profit when the stock market crashes?

Some traders open short positions with instruments such as CFDs, aiming to gain from falling prices. It is a high-risk strategy: rebounds can be sudden, leverage magnifies losses, gaps can bypass stop-losses, and losses can exceed the amount deposited. It is not suitable for everyone, and there is no guarantee of profit.

Risk Warning: Trading Contracts for Difference (CFDs) carries a high level of risk and may not be suitable for all investors. The use of leverage can significantly magnify gains and losses and may result in losses exceeding your initial investment. Prior to engaging in CFD trading, you should ensure that you fully understand the risks involved, carefully consider your investment objectives, financial situation, and level of experience, and seek independent advice where necessary. Past performance is not indicative of future results. Please refer to our legal documents for a comprehensive overview of the risks associated with CFD trading.

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