The way I understood the Expert Market rules in the US was that retail buyers could not buy or sell (with the exception of liquidating), but 'experts' could buy -- basically grey market trades -- just like pre-public stocks could also be traded on the grey market to institutional players who were willing to bear the risk.
However, unlike being relegated to the actual grey-market of no-ticker stocks, there was still some (obvious) validity to the stocks having a ticker symbol, although I admit that I don't quite 'get' what that was, since Expert Market stocks were not supposed to be quotable by market-makers, making them virtually identical to grey market stocks.
