PSDV has had a pretty good run of late, with an additional 150K shares shorted. They must really be behind the curve here. Maybe some had a call from their broker at the end of May.
Let's hope that continues.
Re the 150k additional shorted shares. It's possible that the shorters are simply short against and also held long position. This way they are taking their gain and deferring the tax effect until they unwind both positions.