Bitcoin was down 25% after recently reaching a new high of $1350 before popping back a bit after the SEC released an Order Disapproving a Proposed Rule Change to List and Trade Shares Issued by the Winklevoss Bitcoin Trust.

The key reasoning for the SEC's decision is outlined below:

As discussed further below, the Commission is disapproving this proposed rule change because it does not find the proposal to be consistent with Section 6(b)(5) of the Exchange Act, which requires, among other things, that the rules of a national securities exchange be designed to prevent fraudulent and manipulative acts and practices and to protect investors and the public interest.

The Commission believes that, in order to meet this standard, an exchange that lists and trades shares of commodity-trust exchange-traded products (“ETPs”) must, in addition to other applicable requirements, satisfy two requirements that are dispositive in this matter. First, the exchange must have surveillance-sharing agreements with significant markets for trading the underlying commodity or derivatives on that commodity. And second, those markets must be regulated.

Link to S.E.C. Order: https://www.sec.gov/rules/sro/batsbzx/2017/34-80206.pdf