™An index falling from 100 to 80 illustrates the often-used 20% decline convention; it does not establish when recovery will occur.
Trading
Bear market
A broad, sustained market decline, commonly associated with a drop of roughly 20% or more.
Plain-English context
Put the definition to work.
The 20% convention is a label, not a trading rule, and an individual stock's decline need not describe the whole market.
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