It seems many shorters are ignorant of simple chart stage analysis. The time to short ACX was around $7 back in Aug, 2016. Once ACX was trading below a declining 200-day moving average, the stock was in a stage 4 downtrend. This is the time to short via borrowing stock, or CFDs.
Stage 1 smart money accumulation phase was when the 200-day started to go sideways around early Oct, 2017. When the 130-day traded above the 200-day around early Dec, 2017, ACX went into stage 2 uptrend.
ACX is currently 9th most shorted stock. They will be down a bundle after today's 44% rise. Short covering emergency.