A Bitcoin exchange’s proof-of-reserves report can provide useful evidence about assets and customer balances. Reading it well means separating several questions: Do the coins exist? Can someone authorize their movement? Which customer claims were counted? What does the report say about the business beyond that snapshot?
A verification badge may answer one of those questions accurately without answering them all. The practical task is to identify the claim being tested before deciding how much weight to place on the result.
Start with what Bitcoin can show
Bitcoin’s public records let observers examine transactions and identify coins that remain unspent. As the Bitcoin developer guide explains, wallet balances are represented by unspent transaction outputs, with spending conditions attached. A list of addresses can help establish where reported reserves sit on the network.
The list alone does not establish that the exchange can spend those coins. Someone can publish an address belonging to somebody else. A review therefore needs additional evidence connecting the claimed reserves to the entity presenting them.
Signed messages can help, but their meaning has limits. BIP322, Bitcoin’s generic signed-message specification, explicitly cautions that a signature becomes outdated and that a key holder might sign a message for someone else without agreeing to sign an actual transfer. Its proof-of-funds format also requires checking blockchain state to determine whether listed coins remain unspent. A cryptographic check is evidence about a particular claim, not a permanent guarantee of access.
Understand the customer-balance side
Kraken describes its proof-of-reserves process as an independent accountant combining a snapshot of customer balances into a Merkle tree, collecting signatures associated with on-chain reserves, and comparing the amounts. This is the company’s description of its process, rather than an independent conclusion here about its current financial condition.
A Merkle tree combines records through repeated hashing until they produce one root value. It allows a customer to check that their particular balance was included in the committed dataset without publishing everyone’s account details. Kraken says its verification covers in-scope balances at the review time; later trades and excluded assets are outside that check.
The important inference is narrower than “the whole exchange is solvent.” Showing that your record belongs in a dataset does not, by itself, establish that every other customer or every corporate obligation was included. Inclusion and completeness are separate questions.
Why the denominator matters
Consider an invented example. An exchange demonstrates 100 BTC of reserves and reports 90 BTC of customer claims. That is approximately 111.1% coverage of the reported claims. If another 15 BTC of customer claims was omitted, the same 100 BTC would cover only about 95.2% of the resulting 105 BTC total.
The arithmetic is sound in both cases; the difference is what entered the calculation. This example illustrates why an impressive percentage cannot settle the completeness question. It says nothing about any named exchange.
The PCAOB investor advocate’s March 2023 advisory warns that reserve-review procedures may not address liabilities, customer rights or whether reserves were borrowed for the review. It also notes that a snapshot provides no assurance that assets remain available afterward or that internal controls and governance are effective. Those are different dimensions of financial and operational reliability.
Kraken’s own limitations section acknowledges that its procedure cannot identify hidden encumbrances, prove funds were not borrowed for the review, or establish exclusive possession of private keys. A successful check should be read alongside those qualifications.
Read the actual engagement
Words such as “verified,” “reviewed” and “audited” are not interchangeable descriptions of scope. In its July 2023 investor bulletin, SEC staff explains that proof-of-reserves reports are not equivalent to financial-statement audits under SEC rules and PCAOB standards. Even a PCAOB-registered accounting firm can provide services outside those standards and their associated oversight.
Before relying on a report, read beyond the reserve ratio:
- Check the snapshot date, named legal entities and covered assets.
- Identify which customer balances and other liabilities were examined, and which were excluded.
- Read the procedures, findings, qualifications and applicable professional standards.
- Where supported, verify your own balance against the snapshot rather than today’s account total.
- Ask what evidence addresses borrowed or pledged assets and changes since the review.
These questions turn a broad reassurance into specific, inspectable claims. Proof of reserves can add transparency, especially when customers can check their inclusion and the methodology is clear. Its value comes from knowing precisely what was demonstrated. That evidence should not silently expand into a conclusion about liabilities, ongoing access or whole-business solvency that the report never established.