The Winklevoss twins are only concentrating on Bitcoin because, according to a recent interview, they feel that BTC has the lead and this lead is significant enough to be insurmountable due to the lack of clear significant advantage of the other cryptocurrencies. Also, BTC is accepted by many merchants such as Overstock and TigerDirect so you can actually spend it, which is a requirement for money, it has to be spendable.
They want to start a BTC ETF and all ETFs that I know of are traded as futures and options, so I assume that their ETF will be traded that way, too, when and if they get government approval.
The Winklevoss twins are still working on that one. Coming soon....
thanks
do you know how they would be making their selection of CC or are they just focusing on BTC?