Coinbase has announced that it will be implementing proof-of-reserves for its self-custodied wrapped Bitcoin product, cbBTC. This move comes after several security firms raised concerns about the lack of transparency surrounding cbBTC. Proof-of-reserve is a cryptographic accounting method that allows users to verify that an exchange or custodian actually holds the assets that it claims to hold. This is done by publishing a Merkle tree of the account balances of all users, which can then be verified against the exchange's own records. Coinbase's decision to implement proof-of-reserve is a welcome step towards increasing transparency and trust in the cryptocurrency industry. It is hoped that other exchanges and custodians will follow suit, as this will help to improve the overall security and stability of the ecosystem.