A bull market is a sustained period when stock prices rise broadly, typically defined as a gain of 20% or more in a major index over at least two months. The term shows up constantly in financial news, but understanding what actually drives a bull market, how long they last, and what they mean for your money gives you a much clearer picture of how investing works over time.
The 20% Threshold
The most widely accepted definition comes from a simple benchmark: when a broad market index like the S&P 500 climbs 20% or more from a recent low, analysts call it a bull market. That 20% figure is a convention, not a law. There is no official governing body that declares a bull market the way a meteorologist declares a hurricane. But the threshold is used consistently enough across Wall Street, financial media, and regulatory education materials (including the SEC’s investor education site) that it functions as the standard.
The starting point matters. A bull market is measured from the lowest closing price after a decline, not from some arbitrary date. So if the S&P 500 bottoms out at 3,500 and later crosses 4,200 (a 20% gain), that crossing point is when analysts would retroactively mark the beginning of the bull market at the earlier low.
How Long Bull Markets Typically Last
Bull markets are not brief rallies. On average, they have lasted about 992 days, or roughly 2.7 years, according to data compiled by Hartford Funds. During that span, the average cumulative gain has been nearly 114%. That means if you invested $10,000 at the start of an average bull market and held through its peak, your investment would have roughly doubled.
Some bull markets far exceed the average. The longest in S&P 500 history ran from March 2009 to February 2020, nearly 11 years, and delivered gains of over 300%. Others are much shorter, lasting just a year or so before a new downturn begins. There is no reliable way to predict exactly when a bull market will end, which is why most long-term investors focus on staying invested rather than trying to time the cycle perfectly.
What Drives Prices Higher
Bull markets don’t appear out of nowhere. They tend to emerge when several economic conditions line up at once. The most common ingredients include rising corporate profits, falling unemployment, growing GDP, and accommodating interest rate policies. When companies earn more money, their stock prices tend to follow. When more people are employed and spending, that fuels the corporate earnings growth that keeps the cycle going.
Interest rates play a particularly important role. Lower rates make it cheaper for businesses to borrow and expand, and they also make bonds and savings accounts less attractive relative to stocks. That combination pushes more money into the stock market, which drives prices up further. The post-2009 bull market, for instance, was heavily supported by historically low interest rates maintained by the Federal Reserve for years.
Investor psychology matters too. As prices rise, optimism builds. More people invest, which pushes prices higher still, which attracts even more buyers. This feedback loop can sustain a bull market well beyond what pure economic fundamentals might justify, at least for a while.
Cyclical vs. Secular Bull Markets
Not all bull markets operate on the same timescale. A cyclical bull market is the more common variety, lasting a few months to a few years and closely tied to the business cycle. When the economy expands, stocks rise. When growth slows, the bull market ends and a downturn (bear market) begins. These cycles repeat regularly.
A secular bull market is something bigger. It describes a period of 10 to 20 years or more where the dominant trend is upward, even though shorter bear markets may interrupt along the way. Secular bull markets are powered by deep structural forces: long stretches of strong corporate earnings, favorable demographics, technological innovation, or persistently low interest rates. The key distinction is that in a secular bull market, the pullbacks are temporary and the recoveries keep pushing to new highs over the long run.
What a Bull Market Means for Investors
If you have money in a retirement account, index fund, or individual stocks, a bull market is when your portfolio grows. That sounds straightforward, but there are practical implications worth understanding. During a bull market, nearly every stock tends to rise, which can make mediocre investments look brilliant. It is easy to confuse a rising tide with personal skill. The real test of an investment strategy comes when the bull market ends.
For people who invest a fixed amount regularly, such as through a 401(k) contribution every paycheck, bull markets mean you are buying shares at progressively higher prices. That can feel uncomfortable, but it is a normal part of long-term investing. Historically, staying invested through full market cycles has produced better results than pulling out and trying to re-enter at the “right” time. Missing even a handful of the best trading days in a bull market can significantly reduce your overall returns.
Bull markets also affect decisions beyond the stock market. When portfolios are growing, people feel wealthier and tend to spend more freely. Businesses find it easier to raise capital by issuing stock. Startups attract more venture funding. The ripple effects touch hiring, consumer confidence, and real estate prices.
Where Markets Stand Now
As of early 2025, the current bull market was entering its third year, with major investment firms projecting it would continue. Morgan Stanley’s Global Investment Committee, for example, expected the rally to extend into a fourth year, with an S&P 500 target of around 7,500. Projections like these reflect optimism, not guarantees. Every bull market eventually ends, and the transition can happen quickly. But understanding that you are investing during a bull market helps you set realistic expectations for what comes next.