Proof of reserves is not an audit: what an exchange actually proves
After FTX, exchanges rushed to publish proof of reserves. It is a real improvement on nothing, but it answers only one side of the question that keeps customers safe. Here is what it proves, and what it quietly leaves out.
Published · 3 min read
After several exchange failures, most visibly FTX in November 2022, proof of reserves became a badge that trading venues display to reassure customers. It is a genuine improvement on nothing. It is also routinely oversold, because it answers only one side of the question that actually matters.
Solvency is assets minus liabilities. Proof of reserves is usually strong on assets and weak, or silent, on liabilities.
How it actually works
A well-built proof of reserves has two halves. A third-party accountant takes a snapshot of customer balances and aggregates them into a Merkle tree, a data structure that lets any customer confirm their balance was included without exposing anyone else’s. The exchange then proves control of its on-chain wallets with signed messages, and the accountant checks that the assets meet or exceed the liabilities, producing a reserve ratio. Kraken publishes a semi-annual review, reporting a 102.9 percent bitcoin reserve ratio at its June 2026 snapshot; Binance runs a quarterly version, and OKX a monthly one.
The missing half
The gaps are well documented. As The Block’s July 2026 research primer lays out, a proof of reserves is typically a point-in-time snapshot that can be stale within days, can be gamed by moving or borrowing funds just before the check, does not capture off-chain liabilities such as fiat loans or derivatives margin, and cannot fully prove the wallets are exclusively controlled.
“Necessary but not sufficient.”
Without an independent auditor standing behind the liability figure, customers are still trusting the exchange’s own accounting. Coinbase, a public company, files audited quarterly reports with formal controls, a broader and harder bar than a snapshot attestation, and a reminder of what proof of reserves is not.
What would be better, and what you can do
The stronger version pairs frequent proof-of-reserves attestations with a real financial audit and clear segregation of customer assets. And if you would rather not rely on any exchange’s accounting at all, the alternative is to hold your own keys, which we cover in self-custody explained.
In the meantime, a few checks help: look at the snapshot date and discount a stale one, retrieve your own Merkle proof if the exchange offers it, and never read a ratio over 100 percent as a guarantee.
Our take
Proof of reserves is worth having and worth reading, as a signal of intent rather than a guarantee. Until an exchange pairs it with a real audit and clear asset segregation, the green badge answers a narrow question: did the platform control these specific assets at that moment. That is not the same as safe. This is information, not investment advice.
Frequently asked
Is proof of reserves the same as an audit?
No. Proof of reserves shows an exchange holds certain assets at a point in time, but not its liabilities — so it cannot prove solvency the way a full audit can.
What does proof of reserves actually prove?
That the exchange controlled specific wallets or assets on a given date. It says nothing about what the exchange owes its customers.
What should I look for instead?
A full audit covering both assets and liabilities by a reputable firm. Proof of reserves on its own is not enough.
Sources
- Crypto Proof of Reserves: What It Proves and What It Misses (citing The Block’s July 2026 primer), The Block / Binance Square
- Proof of Reserves, Kraken
- Proof of Reserve: A Step Towards Transparency, Merkle Science