I guess I would say a genuine, fast mechanism for price discovery and liquid trading Bitcoin long and short needs to be available. As long as the ETF sponsor s

I guess I would say a genuine, fast mechanism for price discovery and liquid trading Bitcoin long and short needs to be available. As long as the ETF sponsor stands by to exchange the ETF for Bitcoin and vice versa, shorting isn't really required. If it were a closed-end-fund with no exchanges for the underlying, then you would need ability to borrow/short.