BlackRock has filed to launch a "buffer" Bitcoin ETF that would cap investors' gains in exchange for limiting their losses, according to a filing with the Securities and Exchange Commission on Monday. The iShares Bitcoin Managed Protection ETF, which would trade under the ticker PBIT, "seeks to provide upside exposure to the iShares Bitcoin Trust ETF (IBIT) and/or similar bitcoin exposure up to an approximate limit, while seeking to provide a level of downside protection," the filing says. The management fee has not yet been filled in.