Proof of Reserves: What It Proves and What It Does Not

After the failures of 2022, most large exchanges began publishing reserve attestations. They are a genuine improvement and they are routinely over-interpreted.

What a reserve attestation shows

That the venue controlled certain assets at a specific moment. In better implementations, that those assets equalled or exceeded customer balances at that moment.

The stronger versions use a cryptographic structure that lets an individual customer verify their own balance was included in the total, without revealing anyone else’s.

What it does not show

Liabilities beyond customer balances. An exchange can demonstrate assets covering customer deposits while owing large sums elsewhere. Borrowings, obligations to affiliates and off-balance-sheet arrangements do not appear.

This is the central limitation. Assets without liabilities is half a balance sheet, and the failures that mattered were liability problems.

Continuity. An attestation is a snapshot. Assets can be borrowed for the moment of the snapshot and returned afterwards. Frequent, unpredictable attestation timing mitigates this; a known quarterly date does not.

Whether assets are encumbered. Coins may be visible on-chain and pledged as collateral elsewhere.

Who performed the work. Attestations vary enormously in rigour. Some are performed by major accounting firms under defined standards. Some are performed by firms nobody has heard of, under no standard at all.

What to look for

Feature	Why it matters
Liabilities included	Without it, the exercise is half complete
Individual verification	Lets you confirm your balance is counted
Named auditor with a recognised standard	Determines whether the work means anything
Frequent and unpredictable timing	Reduces the snapshot problem
Address disclosure	Allows independent verification on-chain

An attestation missing the first two is a marketing document.

The structural point

No attestation makes an exchange a safe place for long-term holdings, because the risk is not only fraud. It is also bankruptcy, regulatory seizure, and operational failure, none of which a reserve snapshot addresses.

The rule that survives every case in this category remains: an exchange is where you buy and sell, not where you store. Attestations reduce the probability of the worst outcome for the balance you keep there. They do not change what that balance should be.

What good practice looks like today

The better venues publish reserve data on a rolling basis, include liabilities, use a verifiable structure, and name the firm performing the work. Platforms in regulated jurisdictions additionally file financial information with their regulator, which is a stronger form of the same assurance and is checkable in a public register.

For a working balance, a venue meeting both standards, such as a platform serving European retail customers, is a reasonable choice. For long-term holdings, the answer is a wallet you control, and no attestation changes that.