Some stocks have more sellers than buyers. This causes prices to decline. ASTM is not one of them at the moment. There are generally very few shorts in a stock under five dollars. If you are looking for shorts, look at NFLX which actually has some.
ASTM is going to have a heck of a year, I sold my trading shares at 2.90 (was asking 3.33 and backed off the limit, oh well). Early, but I still have 13 other positions. And some AMST GERN and STEM.
Oh, and if ASTM bases, or declines, I'll re-establish the flipping position.
hans