The formation was 'falsely' started (and entered) from above, which poised the formation to fail (later on). And so we measure the excess above the formation, the "peak", and add it below the formation, as the "valley", but we subtract the top portion of the formation-bust "B1" from "A2" in order to account for the down-move.
SQ under $59.89 is a strong-sell to $50-55 (in no time).
SQ under $59.89 is a strong-sell to $50-55 (in no time).