How far underwater
Distance below the previous high, and how long it took to recover
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How this is calculated
Measured on split-adjusted closing prices, so a split is not mistaken for a crash. Depth is the largest fall from a running high-water mark to a subsequent low; recovery is the first session that closes at or above that old high. Closing prices only: intraday lows contain bad ticks — the 2010 flash crash printed some stocks at a cent — which would produce a fictional -99% decline. Every figure is computed on the full daily series, never on the downsampled curve that is drawn.
The heaviest horizontal line on the chart marks the previous all-time high.