Coinbase is the custodian of nearly ALL Bitcoin ETFs. Coinbase insurance covers a loss of $320mm, while Coinbase already holds over 2 BILLION in Bitcoin. ????

The prospectus for each ETF is published on the websites of each fund with a long PDF explaining probably at least a little of what you are seeking. The excerpt below is from IBIT page 89 prospectus. It gets into way more detail than this too and is 116 pages total

"Bitcoin Custodian The Bitcoin Custodian for the Trust’s bitcoin holdings is Coinbase Custody Trust Company, LLC, and the Trust has entered into the Custodian Agreement with the Bitcoin Custodian. The Sponsor may, in its sole discretion, add or terminate bitcoin custodians. The Sponsor may, in its sole discretion, change the custodian for the Trust’s bitcoin holdings, but it will have no obligation whatsoever to do so or to seek any particular terms for the Trust from other such custodians..... The Bitcoin Custodian will ...."

"Coinbase Global maintains a commercial crime insurance policy of up to $320 million, which is intended to cover the loss of client assets held by Coinbase Insureds, including from employee collusion or fraud, physical loss including theft, damage of key material, security breach or hack, and fraudulent transfer. The insurance maintained by Coinbase Global is shared among all of Coinbase’s customers, is not specific to the Trust or to customers holding bitcoin with the Bitcoin Custodian or Prime Execution Agent and may not be available or sufficient to protect the Trust from all possible losses or sources of losses."- Black Rock IBIT ETF prospectus

NYKNYB