Proof of Reserves (PoR) is a method of cryptographically demonstrating that a custodian, such as an exchange, a stablecoin issuer, a wrapped token issuer, or a tokenized fund, controls assets equal to or greater than the liabilities owed to holders.
Two architectural approaches dominate.
Merkle-tree attestations snapshot user balances, hash them into a tree, and publish the root onchain. Users verify that their own balance was included. Most centralized exchanges adopted this method after November 2022.
Oracle-based Proof of Reserves runs continuously. An oracle network pulls reserve data from onchain wallets, custodians, or transfer agents and publishes it as a live feed that smart contracts can read. If reserves drop below issued supply, minting can halt automatically. Lending markets can pause borrowing. A stablecoin can freeze.
A snapshot tells you what was true last Tuesday. A continuous feed tells you what is true right now.
PoR: How it started?
When FTX filed for Chapter 11 bankruptcy on November 11, 2022, the shortfall later disclosed by the bankruptcy estate reached approximately $8.9 billion in missing customer funds. At the moment of collapse, FTX.com held only 0.1% of the Bitcoin and 1.2% of the Ethereum its customers believed was in their accounts.
The collapse was not a technical failure. It was a verification failure. Users had no way to check whether their balances were actually backed by anything. Proof of Reserves answers that question.
Why Traditional Attestations Fall Short
Most snapshot-based PoR reports are agreed-upon procedures engagements, not audits. The SEC has warned that language such as “successful audit” applied to a PoR report is a red flag. The PCAOB followed with its own advisory in March 2023, stating these reports “are not equivalent or more rigorous than an audit.”
The structural gaps:
- Snapshots can be window-dressed. Assets borrowed the day before a report can leave the day after.
- Liabilities are self-reported. Without full database access, no external party can confirm the denominator.
- Rehypothecation stays invisible. A report showing $10 billion in assets does not prove those assets are unencumbered.
- Mazars suspended all crypto PoR work in December 2022. Armanino exited the sector in March 2023. No Big 4 firm currently performs exchange PoR.
How Oracle-Based Proof of Reserves Works
An oracle-based PoR feed does three things continuously:
- Fetches balances from the addresses, custodians, or transfer agents holding the reserves.
- Compares those reserves to the issued onchain supply.
- Publishes the ratio to a smart contract that any application can enforce.
When a lending protocol consumes a PoR feed, the oracle becomes programmable risk infrastructure. Exposure caps can trigger the moment reserves stop balancing. No governance vote required.
Where This Matters Today
Three categories of onchain assets depend on continuous reserve verification.
Tokenized real-world assets (RWAs). The tokenized US Treasury market reached $15 billion in early April 2026, and BlackRock’s BUIDL fund alone crossed $2.5 billion in total value. These instruments only work if their onchain supply can be proven to match offchain NAV.
Bitcoin liquid staking tokens. Over $4 billion in Bitcoin now sits in liquid staking protocols that route BTC through off-chain custodians into the Babylon protocol. Lombard’s LBTC, at roughly $1.5 billion in total value locked (TVL), runs a real-time PoR feed where oracle nodes verify BTC reserves every 20 minutes and compare them to aggregate LBTC supply across every EVM chain. More than 70 DeFi protocols, including Morpho, Gauntlet, Yearn, and Steakhouse, integrate that feed.
Stablecoins. Ethena’s USDtb, the BUIDL-backed stablecoin, uses RedStone PoR. The total stablecoin market cap crossed $320 billion in April 2026, and legislation like the GENIUS Act, signed July 2025, will mandate monthly reserve disclosures for US issuers starting in 2027.
Key Takeaways:
- Proof of Reserves cryptographically demonstrates that a custodian’s assets match or exceed the liabilities it owes to token holders.
- Snapshot-based attestations have known gaps, and US regulators including the SEC and PCAOB have explicitly stated they are not equivalent to audits.
- Oracle-based PoR runs continuously, publishes onchain, and can be enforced programmatically by smart contracts.
- RedStone is the leading provider of PoR feeds for tokenized real-world assets, Bitcoin liquid staking tokens including Lombard LBTC, and stablecoins including Ethena USDtb.
How is Proof of Reserves different from a financial audit?
A financial audit is a full-scope opinion on an entity’s financial statements, performed under standards such as PCAOB GAAS. PoR is almost always an agreed-upon procedures engagement, which is narrower, snapshot-based, and explicitly not an assurance opinion. Oracle-based PoR adds a continuous onchain layer but still depends on the quality of its upstream data source.
How often is Proof of Reserves data updated?
Update frequency depends on what is being measured. Oracle-based PoR feeds respond continuously to the backing value of the underlying assets, to mint and burn events, and, where relevant, to market prices of the reserves themselves. RedStone’s LBTC feed, for example, recalculates reserves every 20 minutes. Traditional snapshot attestations typically publish monthly or quarterly.
Who needs Proof of Reserves?
Any entity that issues tokens backed by assets held elsewhere. That includes centralized exchanges holding customer deposits, stablecoin issuers, wrapped token issuers, tokenization platforms bringing real-world assets onchain, Bitcoin liquid staking protocols, and DeFi applications that use any of the above as collateral. Regulators are moving in the same direction: the GENIUS Act mandates monthly reserve disclosures for US stablecoin issuers from 2027, and MiCA imposes similar requirements across the EU.
