According to Yahoo Finance, ZTNO has an average daily volume of about 10k shares ($2.5k) so it would be pretty easy to pump the price up. I could probably singlehandedly double the price if I wanted to. It's possible that the 1000% price increase was caused by only a handful (or even just one) trader(s).
This is most of it. EMH can't apply to low float stocks because the ability to borrow is scarce and so the market can't easily correct the price without the supply side taking on enormous asymmetric risk. All it takes is a few million dollars in buying power to keep a small stock up 100 percent and not even the biggest hedgefund can correct the inefficiency.
