A Bitcoin futures E.T.F. falls short of what some purists want: a fund that holds crypto directly. Gary Gensler, the S.E.C. chair, recently suggested that the agency might allow crypto E.T.F.s based on futures — bets on Bitcoin’s price fluctuations rather than the underlying crypto itself — that trade on a highly regulated exchange. Approval for the ProShares E.T.F., which is based on Bitcoin futures that trade on the Chicago Mercantile Exchange, won’t be announced by the S.E.C., but the firm’s final prospectus met with no opposition ahead of its effective deadline, and the N.Y.S.E. is readying for launch tomorrow.