Re: "It would therefore appear that the price can be manipulated both up and down."

I think I see that kind of scam in today's trades.

Someone bought a pile of PTSC paper just before the close today at .09/share for a total purchase of $3683.70. Then they sold a part of that paper, after the close, to some dummy who paid .095/share, for a total purchase of $9.50. That would have given the manipulator a 5.5% gain - if there were no transaction fees. That's about 52 cents.