Bloomberg ETF analyst Eric Balchunas published an article on X, revealing that BlackRock runs its own blockchain node, extracts Bitcoin balances from Coinbase Prime's wallet address every night, and verifies the Bitcoin held by IBIT.
They will show it to institutional clients upon request, but will not publish it publicly globally because they have received a lot of spam (such as sanctioned Bitcoin, NFT), and publishing this information will only lead to an explosion of spam.
Balchunas said: "This is by no means amateur behavior. BlackRock manages about 500 ETFs, and the assets of these ETFs are kept by custodians, and there have been no problems for decades. This is why they and other ETF issuers are so trusted by American advisors."