On low volume, so probably mostly just some shorts

On low volume, so probably mostly just some shorts who got tired of holding and covered. They have to have a pretty large stake to short any stock under $2.50 because of the $2.50 rule. To short 10,000 shares of CYDY, they have to have $25,000 - even if the share price is 50¢. Plus they're paying interest on the borrow.