After rejecting Bitwise's Bitcoin ETF, the latest in a series of attempts, the SEC has clarified that a bitcoin ETF is unlikely to be approved anytime soon.
In order to combat market manipulation, the SEC requires surveillance sharing agreements between major exchanges. At this time the SEC does not have surveillance sharing agreements with the biggest crypto exchanges in the world since the biggest exchanges are generally overseas and not required to share data with the United States government. It seems there is no hope for a Bitcoin ETF under the current administration. There is some slight hope that the next administration will have a better attitude towards Bitcoin ETFs, although a new administration will not be in place until 2021 or 2025.