Dark pools

A hedge fund that sells shares in an open priced environment.  The shares can then be traded inside a  private ringed fence, traded for other securities and possibly using a private blockchain for limited set of members. This is using the shares as cash, all the member subject to account rules to prevent double spending, possibly using privately issued ID cards needed to initiate a trade, not quite a cash card but close enough.

So a dark pool is the wealthy getting the sandbox first, us little browns locked out because we don't have secure element.  This is a cause of coordination failure.