A bear market occurs when the stock market falls by 20% from its highs for at least a two month period. As a bear market starts and prices begin tumbling, investors sell into fear, fueling the downturn. The last sustained, large bear market was the Financial Crisis, in which the S&P 500 lost 50% of its value.
Bear markets come in two flavors — cyclical and secular. A cyclical bear market lasts for only a few weeks or even months. A secular bear market lasts for years. During each of the two bear markets, there may be sharp rallies, but they do not last. The market reverts back lower and continues its downward trend.
