The definition
The middle value of a company's absolute stock moves after earnings prints — half its prints moved more than this, half moved less.
How it is computed
Take the absolute moves of a company's counted prints — each move's size, with its direction set aside — and line them up from smallest to largest. The middle value of that line is the median absolute move.
The method uses medians rather than averages, so a single outsized reaction does not pull the figure away from the middle print of the set.
On a base-rate card
The median field is read beside the prints counted and the hit rate. The hit rate states how often moves ran large; the median states the size of the middle move. A median resting on few prints carries the small-sample flag, and the flag travels with the figure wherever the figure is used.
What it is not
The median absolute move is not a range and not a bound: half of the counted prints moved more than it, and the largest reactions in a set sit far above it.
It is not an average move, and it is not a typical gain or loss. Direction is set aside before the middle is taken, so the figure describes size only.