This page looks at what happened during bull and bear market periods for U.S. equities. The top chart shows the duration and loss during bear markets. A bear market is usually generally defined as a period where prices in a market are falling or expected to fall. For the chart, we have used periods where we see a 20% or more decline from the previous market high to classify a bear market. We can use this to compare the duration and severity of different market periods over history. The table at the bottom illustrates the different drivers of a bear market. It shows that lofty valuations tend not to be a reliable predictor of bear markets. Recession is a key reason for bear markets that last more than a year.