A bear market is the label traders use when a major equity index has fallen about 20 per cent from its recent peak. It is more than a bad week. It is a sustained retreat that usually forces portfolios, company plans and household confidence to adjust. For beginners, the 20 per cent rule is the cleanest way into the idea.
The 20 per cent drop rule
Most market practitioners treat a decline of 20 per cent or more from the high as a bear market for that index. The S&P 500, Nasdaq and FTSE 100 are often judged on that measure. The definition is a convention built from decades of market history, not a regulator’s statute. Still, once the threshold is crossed, commentary, fund flows and risk limits tend to shift in a more defensive direction.
Bear markets vary in length. Some last a few months; others stretch across a year or more. Depth varies too. A shallow bear may stop near the 20 per cent line. A deep one can run much further if recession, credit stress or a broken growth narrative keeps selling alive. The shared feature is the scale of the peak-to-trough loss, not a single dramatic session.
How a bear differs from a correction
A correction is the lighter cousin: roughly a 10 per cent fall from the peak. Many corrections reverse before they ever reach bear territory. A bear market has already travelled through that first 10 per cent and kept going. Mixing the two words muddies risk talk. If you want the shorter drawdown explained alone, see what counts as a stock market correction.
Crashes are different again. They are fast, disorderly plunges that can happen inside either a correction or a bear. Speed is the hallmark; the eventual label still depends on how far prices travel from the high. Our comparison piece on correction versus bear versus crash lays the three terms side by side.
What usually drives a bear
Bears rarely have a single cause. Tighter monetary policy, a profits recession, a credit event or a long period of stretched valuations can all play a part. Often several arrive together. As prices fall, leveraged investors cut exposure, volatility rises and safe-haven assets such as the dollar or high-grade bonds can attract flows. That feedback loop is why bears feel different from garden-variety pullbacks.
Sector behaviour changes as well. Cyclical and high-valuation growth shares often lead on the downside. Defensive industries may lag the decline or even hold relative strength for a time. Breadth usually worsens: fewer stocks make new highs, and rallies fail more often. None of those patterns is a crystal ball. They are the traces that show risk appetite is shrinking.
Living through a bear without the drama
Media coverage of bear markets tends to pile on fear. The practical task for a beginner is narrower: know how far the index has fallen from its high, watch whether corporate earnings guidance is deteriorating, and notice if credit conditions are tightening. Those three threads explain more of the journey than any single scary headline. Rallies inside bears are common and often fierce; they do not automatically end the regime. Waiting for confirmation that breadth, credit and earnings have stabilised is duller than calling a bottom, and usually wiser.
How long do bear markets last?
History says most equity bear markets in developed markets resolve within months to a couple of years, but averages hide ugly outliers. Trying to time the exact low is a common beginner trap. More useful is recognising the regime: earnings estimates are being cut, credit is less forgiving, and “buy every dip” stops working as cleanly as it did in the prior advance.
For UK traders watching US and Asian indices overnight, a US bear can spill into London’s open through futures and sentiment, even when domestic news is quiet. That transmission is why global benchmarks still matter on a UK desk. Building a calm framework for these regimes is exactly what a structured skills check is for, and the free assessment at assessment.samuelandcotrading.com is a sensible next step.
