But one feature of the new US launches could limit their success: they are based not on the price of bitcoin directly, but on bitcoin futures.
In addition, any ETF that relies on futures can underperform the underlying asset it is supposed to track.
The ETFs are intended to closely track the bitcoin price so the most in-demand futures contract is the one that expires closest to the current date, known as front month or spot contracts.
CME Group, however, has imposed limits on the number of contracts one party can buy, to stop one company cornering the market.
If the market expects the price of bitcoin to rise over the longer term, then the price of longer term futures contracts will rise above the short-term contracts, in what is known as contango.
The version that will be used to form a bitcoin price index will not be in the hands of the ETF sponsor, but a decision of an industry benchmarks committee.