On Tuesday or Wednesday I mentioned that ARTH looked like the pumper/dumpers were in control of it. On no news, it was down around .53 then, from a high of .80 just a couple weeks before.
It magically reversed upward late Wednesday afternoon, and now whammo, it's up 8%.

Pumper/dumper gangs absolutely do exist, as I know from my own experience of being invited to join two of them.