A bull market describes a sustained period during which asset prices — most commonly stocks — are rising or expected to rise, generally defined as a rise of 20% or more from a recent low. It reflects broad investor optimism and often coincides with a growing economy.
Bull markets matter to everyday investors because they shape the environment for retirement accounts, index funds, and other investments; understanding what one looks like helps set realistic expectations rather than assuming rising prices are permanent.
How a bull market is defined and measured
Analysts typically mark the start of a bull market from the lowest closing point before a 20%-or-greater rise, often measured using a broad index like the S&P 500. The 20% threshold is a convention, not a law of markets, so different data providers occasionally mark start and end dates slightly differently.
For example, if the S&P 500 falls to a low of 3,500 and later closes at 4,200 or above, that 20% climb from the low would generally be labeled the start of a bull market.
How long do bull markets typically last?
Historically, U.S. bull markets have lasted anywhere from under a year to over a decade, with an average duration of roughly 2.5 to 5 years depending on the measurement period studied, and average cumulative gains often well over 100%.
Because durations vary so widely, trying to precisely predict when a bull market will end is unreliable, which is part of why strategies like diversification and staying invested over the long term are commonly discussed as ways to participate in growth without needing to time entries and exits.
What to keep in mind during a bull market
Rising prices can create a temptation to take on more risk than intended, chase recent winners, or abandon a diversified plan. Reviewing your own goals, time horizon, and risk tolerance periodically — rather than reacting to headlines — is a commonly recommended discipline regardless of market direction.
It's also common for enthusiasm during a bull market to spread beyond stocks into speculative assets, as seen with certain technology stocks in the late 1990s or various niche assets in more recent cycles. Rising prices alone don't indicate that an investment is sound, which is why sticking to a plan based on goals rather than recent performance is often emphasized.
Historical bull markets and how they've compared
Some of the longer U.S. bull markets on record include the 1990s expansion, which ran for roughly 9 years into 2000 with cumulative gains exceeding 400% on the S&P 500, and the 2009-2020 bull market, which ran for roughly 11 years and produced gains estimated at over 300-400% from its financial-crisis low. Shorter bull markets, sometimes lasting only 1-2 years, have also occurred, often following sharp prior declines.
Comparing these periods shows there's no single 'typical' bull market shape — some climb steadily for years, while others feature sharp early gains followed by more moderate growth. This variability is one reason analysts caution against assuming any current bull market will match the length or magnitude of a specific past example.
Common investor mistakes during bull markets
A frequent mistake is performance chasing — shifting money into whatever asset or sector has recently produced the largest gains, often after much of the run-up has already happened. Another is underestimating risk: because a bull market can make volatility feel like a distant memory, some investors gradually take on more risk than their actual goals or time horizon call for.
A third common issue is confusing a rising market with individual investing skill, which can lead to overconfidence and larger, less diversified bets right before a downturn. Financial educators generally suggest that a bull market is a good time to rebalance a portfolio back to its target allocation, rather than a signal to abandon a diversification plan altogether.
Common mistakes
- Assuming a bull market means prices only go up — sharp short-term pullbacks (corrections) can still happen within a broader bull market.
- Believing you can reliably predict exactly when a bull market will end and exit at the top.
- Treating recent strong returns as a guarantee of similar future returns.
- Increasing risk-taking or leverage simply because the overall market trend has been positive.
- Chasing whichever sector or stock had the largest recent gains rather than sticking to a diversified plan.
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Open Decision Lab →Frequently asked questions
What's the opposite of a bull market?
The opposite is a bear market, generally defined as a drop of 20% or more from a recent high, reflecting sustained investor pessimism.
Can different asset classes be in a bull market at the same time?
Yes — the term applies to any asset class, so stocks, bonds, real estate, or commodities can each be described as being in their own bull market independently.
Does a bull market mean the economy is doing well?
Often bull markets coincide with economic growth, but stock prices reflect expectations about the future, so markets can rise even during uncertain economic periods, or vice versa.
Should I invest differently during a bull market?
Many long-term strategies, such as maintaining a diversified portfolio and consistent contributions, are designed to work across both bull and bear markets rather than being adjusted for market direction.
How many bull markets has the stock market had historically?
The U.S. stock market has gone through more than a dozen distinct bull markets since the mid-20th century, alternating with bear markets and corrections along the way.