How many shares have traded on the open market since the announcement of the placement?

I don't know if it's much >20MM, but even if it were, it would be a rather large stretch to say that Dundee could have picked them all up, wouldn't it? You're statement implies no other players in the market, which is of course untrue. Reality is that if the other players saw anyone trying to pick up in excess of 20MM share inside of a month (the bought deal was announced July 13), they would run the price up.