Not that it's that important but I had heard a number of years ago that Richardson's out of Winnipeg were the ones who had initially been providing a market (if that's what you want to call it) to sell unwanted Zenith shares.  As I said just what I heard, don't know if it's true. I do know a while back I phoned and tried to buy some through TD and was told they couldn't help me but if I wanted to sell some they could accommodate that. Not much of a "market" IMO.  I did give them a bit of a hard time then, stating that it seemed a little sketchy that someone else was able to buy if I wanted to sell yet I couldn't buy. The broker I was talking to agreed but said that was the way it was. 

Further to this, it is my understanding that management was caught unaware (shocking I know!!) of the rules surrounding widely held, reporting prívate companies and were thus suprised by the OTCBB listing.  Again, just what I heard. I agree with management that the "market" price is not reflective of the value within the company but then I think the current private placements undervalue the company as well when I look at other biotech valuations. JMO though. 

As far as the validity of the shares, like others my understanding is as long as the cusip number is correct the shares are good. The fact that people who have bought some through the "market" are having them mixed in with existing ZEN shares would seem to confirm this. If you want further confirmation you should be able get that from your brokerage or you could try Lloyd McLellan at BLG Calgary (ZEN's lawyer) whose practise includes capital markets.