Stock market crash: causes, history and what happens

What causes a stock market crash? Key triggers explained

Stock market crashes rarely occur because of a single event. Instead, they are usually caused by a combination of factors that weaken confidence and increase selling pressure.

Common triggers include:

• Economic recessions or slowing growth

• Rising interest rates

• Excessive market speculation

• Geopolitical tensions or wars

• Financial system instability

• Sudden shifts in market sentiment

When traders and investors begin selling rapidly, falling prices can trigger further selling, increasing volatility and accelerating declines.

Major stock market crashes in history

Wall Street crash (1929): causes, impact and lessons

The Wall Street crash of 1929 remains one of the most significant financial collapses in history.

Following a period of strong speculation and rising share prices during the 1920s, markets experienced a sharp reversal in October 1929. Panic selling intensified over several trading sessions, contributing to the Great Depression.

Key lessons

• Excessive leverage can amplify losses

• Speculative bubbles can become detached from economic fundamentals

• Investor confidence plays a major role in market stability

Black Monday (1987): rapid global market decline

On 19 October 1987, global stock markets experienced one of the largest single-day declines in history.

The Dow Jones Industrial Average fell more than 20% in one session. Contributing factors included automated trading systems, market panic and concerns about economic conditions.

Key lessons

• Market liquidity can deteriorate rapidly during periods of panic

• Volatility can spread quickly across global financial markets

• Technology and trading systems can amplify price movements

Dot-com bubble burst (2000): causes, impact and lessons

During the late 1990s, technology stocks experienced rapid growth driven by optimism surrounding internet companies.

Many businesses traded at valuations disconnected from profitability. When expectations weakened, technology shares fell sharply and many companies failed.

Key lessons

• Strong narratives do not eliminate valuation risk

• High-growth sectors can experience prolonged volatility

• Diversification remains important during speculative periods

Global financial crisis (2008): banking collapse and recession

The 2008 financial crisis was triggered by problems within the US housing market and banking sector.

As mortgage-related assets lost value, financial institutions faced severe losses, creating wider instability across global markets.

Key lessons

• Financial system risks can spread rapidly through global markets

• Excessive debt can increase vulnerability during downturns

• Government and central bank intervention can influence recovery

Covid-19 market crash (2020): pandemic-driven volatility

In early 2020, global stock markets declined sharply following the outbreak of Covid-19.

Economic shutdowns, uncertainty and reduced business activity contributed to rapid market declines before unprecedented fiscal and monetary support measures helped stabilise markets.

Key lessons

• Markets can react quickly to unexpected global events

• Policy responses can significantly affect recovery speed

• Volatility can increase sharply during periods of uncertainty

What happens during a stock market crash?

During a crash, markets often experience:

• Increased volatility

• Rapid declines in share prices

• Reduced investor confidence

• Higher trading volumes

• Wider price swings across sectors and asset classes

Certain sectors may be affected differently depending on the underlying cause of the downturn.

How traders and investors respond to market crashes

Different market participants respond to crashes in different ways.

Some investors focus on long-term investing and diversification, while others may reduce their exposure to stocks or seek defensive assets.

Traders may monitor:

• Volatility levels

• Central bank responses

• Economic data and earnings trends

• Changes in market sentiment

Periods of market stress can increase risk significantly, and prices may move unpredictably.

Risk management during volatile markets

Risk management becomes especially important during market downturns.

Common considerations include:

• Diversification across sectors and asset classes

• Position sizing

• Avoiding excessive leverage

• Reviewing long-term financial objectives

Leveraged trading products can magnify both gains and losses.

Key takeaways

• Stock market crashes involve rapid and widespread declines in share prices

• Crashes are often driven by economic, financial and behavioural factors

• Historical crashes provide insight into market risk and investor psychology

• Volatility and uncertainty typically increase during downturns

• Risk management and diversification remain important considerations

Past performance is not a reliable indicator of future results.