What to Do When the Stock Market Crashes
Introduction
Sooner or later, it happens. You open your investment app and see red numbers: down 10%, 20%, sometimes more. The news talks of crisis, panic, and the end of an era. And a very convincing inner voice whispers: "Sell now before you lose everything."
Stock market downturns are among the moments that most define a long-term investor's results—not because you need to do something brilliant, but because it is so easy to do something destructive. This article explains why market drops happen, what history shows, and how to prepare so you can weather them without ruining your plan.
The market does not punish you for downturns; it punishes you for selling during them.
Downturns Are Part of the Landscape
Investing in stocks means accepting that their value will fluctuate. Drops of 10% are common, 20% declines happen every few years, and deep crashes occur several times in a lifetime. Consider two recent examples from the S&P 500 index, which tracks roughly 500 large U.S. companies:
- 2007–2009 financial crisis: the index fell about 57% between October 2007 and March 2009. It recovered its previous peak in 2013.
- 2020 pandemic crash: it dropped roughly 34% in just over a month between February and March, and recovered its previous high by August of that same year.
In both cases, investors who held onto diversified portfolios eventually recovered. Those who sold at the bottom turned a temporary paper loss into a permanent real loss.
This does not guarantee that every downturn will recover quickly—some markets have taken many years—but it shows why broad diversification and a long time horizon are so essential.
The Cost of Getting Out
One of the most cited findings on this topic comes from J.P. Morgan Asset Management's annual studies: an investor who stayed in the S&P 500 over a twenty-year period but missed just the ten best days ended up with roughly half the final wealth of someone who stayed invested the entire time. And many of those best days occurred right next to the worst days, in the middle of a crisis.
In other words, pulling your money out to "wait until the dust settles" usually means missing the recovery itself.
Why Our Instincts Betray Us
Behavioral economics explains this urge well:
- Loss aversion: Daniel Kahneman and Amos Tversky showed that a loss hurts roughly twice as much as an equivalent gain feels good.
- Recency bias: we tend to assume that whatever is happening right now will keep happening indefinitely.
- Herd behavior: when everyone else is selling, staying put feels reckless.
Knowing that these reactions are normal human wiring helps you avoid obeying them automatically.
How to Prepare Before the Crash
The most important decisions are made before a crisis hits:
1. A full emergency fund. If you lose your job in the middle of a recession, you will not be forced to sell investments at the worst possible moment. 2. Short-term money kept out of the stock market. Money you will need within the next few years does not belong in equities. 3. An asset allocation you can stomach. If a 30% drop in the stock portion of your portfolio would make you panic-sell, your portfolio carries too much risk for you. 4. A written investment plan. One or two pages stating your goals, your target asset mix, and exactly what you will do when the market drops.
What to Do During a Downturn
- Do not make decisions in the heat of the moment. Wait at least a few days before making any change.
- Re-read your written plan. Did something change in your life or your goals, or did only market prices change?
- Keep contributing. Regular monthly contributions buy more shares when prices are low.
- Rebalance if appropriate. If stocks fell sharply and now sit below your target percentage, restoring your portfolio to its original mix means buying while prices are cheap.
- Look less often. Checking your portfolio every day increases anxiety without adding any value.
When You Should Review Your Portfolio
A market crash is not a reason to abandon a sound plan, but it can reveal something useful: if you discover that you cannot tolerate as much risk as you thought, it is reasonable to adjust your asset mix—ideally once the market has calmed down, not in the middle of a panic. It also makes sense to review your holdings if you were heavily concentrated in a single company or sector.
Common Mistakes
Selling everything at the bottom. It locks in a temporary decline as a permanent loss.
Trying to call the bottom. Nobody knows when a downturn will end.
Pausing automatic contributions. That means stopping your purchases right when shares are on sale.
Spending hours glued to financial news and price tickers.
Investing money in stocks that you will need soon.
Conclusion
Stock market drops are inevitable, but the damage they cause depends largely on how you react. With an emergency fund, short-term cash kept out of the market, a tolerable risk mix, and a written plan, a market crisis becomes an uncomfortable stretch rather than a financial disaster. This week, write down on a single page what you will do the next time your investments drop by 20%, and keep it somewhere you can easily find when that day arrives.
References
- J.P. Morgan Asset Management. Guide to Retirement (annual editions). jpmorgan.com.
- Kahneman, D., & Tversky, A. (1979). Prospect theory: An analysis of decision under risk. Econometrica, 47(2), 263-291.
- Barber, B. M., & Odean, T. (2000). Trading is hazardous to your wealth: The common stock investment performance of individual investors. The Journal of Finance, 55(2), 773-806.
- Bogle, J. C. (2017). The Little Book of Common Sense Investing (updated ed.). Wiley.