Stablecoin ETF risk: how to calculate reserve backing ratio

The reserve backing ratio is a balance-sheet calculation:

eligible reserve assets ÷ outstanding token liabilities

A ratio of 1.00 means the issuer reports one dollar of eligible assets for each dollar of tokens in circulation. A ratio above 1.00 indicates nominal overcollateralization. A ratio below 1.00 indicates a reserve shortfall.

That calculation is simple for a single-issuer stablecoin. It becomes less direct when a stablecoin ETF, stablecoin exchange traded fund, or basket-backed token holds other stablecoins as its reserve assets. The structure adds another liability layer. The top-level token can report full backing while remaining exposed to a depeg, redemption halt, custody failure, or liquidity mismatch in an underlying asset.

The correct analysis is therefore not limited to the published reserve total. It requires a look-through calculation of asset quality, redemption access, maturity, issuer concentration, and collateralization.

The reserve backing ratio starts with liabilities

For a conventional fiat-backed stablecoin, the denominator is the total circulating supply. If an issuer has 10 billion tokens outstanding, it has 10 billion units of token liability.

The numerator includes only assets that qualify as reserves under the relevant legal and contractual framework. Cash, bank deposits, short-dated Treasury instruments, and other high-quality liquid assets may qualify. Corporate investments, operating cash, unsecured receivables, or long-duration securities may not.

The basic formula is:

Reserve backing ratio = market value of eligible reserves / circulating supply

An example:

• Circulating supply: $10 billion
• Eligible cash and Treasury reserves: $10.15 billion
• Reported backing ratio: 101.5%

The ratio is positive. It is not a guarantee of immediate one-dollar redemption for every holder. The result depends on valuation, custody, settlement timing, and the issuer’s ability to convert reserves into fiat-equivalent liquidity.

For reserve analysis, the following figures matter:

• Gross reserves: the total reported value of assets.
• Eligible reserves: the portion permitted to back token liabilities.
• Encumbered reserves: assets pledged, frozen, or otherwise unavailable for redemption.
• Unrealized valuation changes: losses or gains caused by market prices.
• Outstanding liabilities: the full token supply, including tokens held on exchanges and in wallets.
• Available liquidity: the amount that can be converted into redemption cash within the required time window.

A reserve report can show a ratio above 100% while available liquidity is lower than the liability base. That is the central distinction between collateralization and liquidity.

A 1:1 reserve ratio measures nominal asset coverage. It does not measure the time required to turn those assets into redemption cash.

What counts as a usable reserve

The reserve asset must be evaluated across three dimensions.

Value. The asset must cover the token liability at its current market value.

Eligibility. The asset must be allowed under the issuer’s governing rules or regulation.

Availability. The asset must be accessible when holders request redemption.

A Treasury bill that matures in 90 days may have high credit quality. It is not the same operational asset as cash in a redemption account. The difference is a liquidity delta: the gap between the value reported on the balance sheet and the amount immediately available for settlement.

The calculation should therefore separate headline backing from near-term backing:

Immediate liquidity ratio = cash and same-day liquid assets / outstanding liabilities

Eligible reserve ratio = all eligible reserve assets / outstanding liabilities

If a stablecoin reports 102% eligible reserve coverage but only 78% in same-day liquidity, the structure is solvent on paper and exposed to a redemption run in practice. The maturity profile determines whether the issuer can sell or redeem assets without delay or loss.

A stablecoin ETF introduces a second liability layer

A single-issuer stablecoin has a direct relationship between the issuer and the token holder. A nested stablecoin has at least two.

The top-level token issues its own liabilities. It then holds other stablecoins in the reserve pool. Those underlying stablecoins have separate issuers, reserve policies, custodians, banking relationships, and redemption processes.

This structure resembles a stablecoin ETF because the top-level instrument provides exposure to a basket of fiat-pegged tokens. It may hold USDC, USDT, USD1, or other assets rather than direct dollars or Treasury instruments.

The top-level calculation is:

Top-level backing ratio = market value of underlying stablecoins and other eligible assets / top-level token supply

That is necessary but incomplete. The underlying assets must be discounted for their own backing and liquidity risks.

A look-through calculation can be expressed as:

Effective backing ratio = Σ(asset market value × asset backing factor × liquidity factor) / top-level token liabilities

The backing factor reflects the estimated reserve quality of each underlying token. The liquidity factor reflects how much of that value can be realized within the required redemption window.

This is not a statutory formula. It is a risk model. The purpose is to avoid treating every dollar-pegged token as identical cash.

Example: a basket-backed token

Assume a nested token has 100 million units outstanding. Its reserve pool contains:

The headline backing ratio is 100%.

The risk-adjusted backing ratio is 94.95%.

The difference is not an accounting error. It is the result of applying discounts for underlying reserve uncertainty and redemption liquidity. If the top-level token promises one dollar of redemption, the relevant question is not whether the basket has a nominal market value of $100 million. The question is whether the basket can produce $100 million of settlement liquidity when all holders attempt to redeem.

The calculation becomes more sensitive when one asset dominates the pool. A basket with 90% USDC and 10% USDT remains highly dependent on USDC infrastructure. A basket with equal weights has lower single-issuer concentration but more exposure to cross-issuer differences in reserve composition and redemption terms.

Depeg transmission is mechanical

Assume the top-level token holds:

• $50 million of USDC
• $30 million of USDT
• $20 million of USD1

Its total reserve value is $100 million against 100 million top-level tokens. The reported ratio is 100%.

If USDC trades at $0.87, as it did temporarily during the Silicon Valley Bank collapse in March 2023, the marked value of the reserve pool becomes:

• USDC: $43.5 million
• USDT: $30 million
• USD1: $20 million
• Total: $93.5 million

The top-level backing ratio falls to 93.5%, even if the top-level issuer has not lost a dollar from its own bank account. The loss is transmitted through the reserve asset.

This is the defining risk of a nested stablecoin. The top-level issuer inherits the operational and market structure of the instruments it holds.

The transmission can occur through several channels:

1. Market-value transmission. An underlying stablecoin trades below one dollar. The basket’s mark-to-market value falls.

2. Redemption transmission. The underlying issuer limits or delays redemptions. The top-level issuer cannot liquidate the position at par.

3. Banking transmission. A reserve bank becomes inaccessible. The token remains backed in aggregate but loses immediate settlement liquidity.

4. Custody transmission. Assets are held with a custodian or platform that freezes transfers.

5. Concentration transmission. Several underlying tokens depend on the same bank, payment rail, or market maker.

6. Oracle transmission. A pricing feed reports stale or incomplete data, delaying recognition of the impairment.

The nominal ratio captures only the first layer. A serious model maps the full chain.

The regulatory benchmark is 100%, not instant liquidity

The US GENIUS Act, signed in July 2025, and the EU’s MiCA framework establish a 1:1 reserve standard for regulated stablecoins. Reserves must consist of high-quality liquid assets and remain segregated from corporate funds.

The rule changes the minimum asset standard. It does not eliminate settlement risk.

Under MiCA, at least 30% of reserves must be held as bank deposits. For tokens designated as significant by the European Banking Authority, the requirement rises to 60%.

That structure creates a specific analytical issue. Bank deposits are fiat-equivalent assets, but they are not all identical. A deposit may be:

• immediately withdrawable;
• subject to notice or operational limits;
• concentrated at one institution;
• exposed to a bank failure process;
• held through a correspondent structure;
• available only during banking hours or through a defined payment channel.

The regulatory ratio should therefore be separated from the operational liquidity ratio.

A product can pass the first test and fail the second or third. That is not a contradiction. It reflects different definitions of risk.

GENIUS Act-style reserve assets

For a stablecoin ETF or basket token designed around short-term Treasury instruments, maturity becomes a principal variable. The ProShares GENIUS Money Market ETF, launched on NYSE Arca in February 2026, invests in Treasury instruments with a maximum maturity of 93 days to align with GENIUS Act requirements.

A 93-day maturity cap limits duration exposure. It does not create same-day liquidity by itself. A fund still depends on market depth, settlement, custody, and the mechanics of converting securities into cash.

The same logic applies to tokenized Treasury products. A short maturity profile reduces interest-rate sensitivity and price volatility. It does not remove:

• settlement timing;
• trading-hour limits;
• transfer restrictions;
• fund-level redemption gates;
• custody dependencies;
• price deviations during stressed markets.

The asset is high quality. The redemption process remains a separate risk variable.

MiCA and the bank-deposit channel

MiCA’s deposit requirements have an additional implication for nested structures. If a top-level token holds a regulated stablecoin, the top-level issuer is indirectly exposed to the underlying issuer’s deposit allocation.

A reserve pool may therefore contain several tokens that appear separate but depend on the same banking system. The visible asset count overstates diversification if the underlying reserve banks overlap.

The relevant question is not “How many stablecoins are in the basket?” It is:

• How many independent issuers exist?
• How many independent banks hold the reserves?
• How many custodians control access?
• How many payment rails process redemptions?
• What percentage of the pool can be liquidated within one business day?
• What assets are subject to legal or operational encumbrance?

Diversification by ticker is not the same as diversification by counterparty.

The SVB episode shows why nominal backing can fail operationally

Circle disclosed that $3.3 billion of USDC reserves were held at Silicon Valley Bank when the bank collapsed in March 2023. USDC temporarily traded as low as $0.87, a 13% decline from its intended peg.

The event is useful because it separates two concepts that are often merged in stablecoin commentary.

USDC’s reported reserve claim was based on aggregate backing. The depeg reflected access and settlement uncertainty. Holders did not need to prove that the reserves had disappeared. They needed to know whether the affected assets could be accessed and whether redemptions would clear at par.

The sequence was structurally clear:

1. A reserve bank failed.

2. A portion of the reserve pool became temporarily inaccessible.

3. Market participants repriced the token below one dollar.

4. Secondary-market liquidity absorbed the uncertainty at a discount.

5. Confidence in par redemption returned after the resolution path became clearer.

A nested stablecoin holding USDC would have transmitted that discount into its own reserve calculation. If the basket token continued trading at one dollar while the underlying USDC reserve was valued at $0.87, the top-level token would have required additional liquidity or collateral to preserve its own peg.

The lesson is narrow but material: reserve backing is only as strong as the weakest redemption channel that matters during a stress event.

A bank failure can impair a fully backed token before it impairs the value of the underlying reserves. Access is part of collateralization.

Stress-testing the reserve pool

A usable model should apply separate shocks rather than one broad haircut.

For a basket-backed token, calculate at least four scenarios:

• Underlying depeg: one reserve token falls to $0.87.
• Redemption delay: one asset remains valued at par but cannot be converted for several days.
• Custodian impairment: a defined percentage of the reserve pool becomes temporarily unavailable.
• Liquidity spread: assets can be sold only below their reported net asset value.

Example:

A 1 billion-token product holds:

• 400 million USDC
• 350 million USDT
• 150 million USD1
• 100 million in cash

The headline reserve value is $1 billion.

Under a USDC depeg to $0.87, with all other assets remaining at par:

• USDC value falls from $400 million to $348 million.
• Total reserve value falls to $948 million.
• Headline backing declines to 94.8%.

If the same scenario includes a 5% liquidity haircut on USDT and USD1:

• USDC: $348 million
• USDT: $332.5 million
• USD1: $142.5 million
• Cash: $100 million
• Stressed reserve value: $923 million
• Stressed backing ratio: 92.3%

The result measures a defined scenario. It is not a prediction. The value of the model is that it exposes the reserve shortfall produced by specific assumptions.

Reserve reports require an attestation, not only a headline number

An attestation is not the same as a full audit. It generally confirms selected financial information at a point in time or over a defined reporting period. The scope, date, valuation method, and asset eligibility determine how much weight the number deserves.

The reserve file for a stablecoin ETF or nested token should provide enough detail to reconstruct the ratio. At minimum, the analysis needs:

• token supply at the reporting timestamp;
• reserve holdings by asset;
• issuer and custodian for each holding;
• maturity dates for Treasury instruments;
• bank names and deposit balances;
• encumbrances or liens;
• redemption terms for underlying stablecoins;
• valuation prices and price-source methodology;
• pending redemptions and unsettled transactions;
• related-party exposures;
• frequency of reporting.

A report that states “reserves exceed liabilities” without disclosing the asset mix is not sufficient for look-through risk analysis. It establishes a conclusion but not the inputs.

The time gap also matters. A quarterly attestation can be accurate on its reporting date and stale during a rapid supply expansion or redemption event. Stablecoin liabilities move continuously. Reserve data often does not.

Supply changes alter the denominator

Minting and burning create immediate changes in token liabilities.

If a top-level issuer mints 200 million tokens but does not yet acquire or settle the corresponding reserves, the denominator rises before the numerator. The reported ratio temporarily falls.

If the issuer acquires reserves before mint settlement is recorded, the sequence reverses. The ratio can remain stable while the composition changes.

Chronological transaction analysis should therefore track:

1. token mint;

2. reserve acquisition;

3. custody settlement;

4. supply update;

5. redemption request;

6. token burn;

7. reserve release.

On-chain supply data can identify the token movement. It may not identify the final legal owner, bank deposit, or off-chain Treasury settlement. This is where on-chain analysis and attestations must be combined.

The same limitation applies to USDT and other large fiat-pegged assets. USDT had a market capitalization of approximately $199 billion as of December 2025. A large supply base increases the absolute value of reserves and the scale of potential redemption flows. It does not, by itself, establish the real-time reserve backing ratio.

The exact real-time ratio remains unknown when an issuer publishes periodic attestations rather than continuous reserve data.

Stablecoin ETF reserves should be analyzed by look-through exposure

A conventional exchange traded fund normally publishes a portfolio, net asset value, creation and redemption mechanism, and custody structure. A token that holds a basket of stablecoins may resemble an ETF economically without sharing the same legal structure or disclosure regime.

That distinction matters. A “crypto stablecoin ETF” can describe several different products:

• a regulated fund holding Treasury bills and cash;
• a fund holding shares or interests linked to stablecoin issuers;
• a token holding other stablecoins directly;
• a protocol token using stablecoins as collateral;
• an index product with synthetic exposure rather than direct holdings.

The reserve calculation changes in each case.

For a direct basket, use the market value of the underlying tokens and apply issuer-level discounts.

For a Treasury fund, analyze net asset value, maturity, liquidity, and fund redemption terms.

For a synthetic product, identify the counterparty and collateral agreement. The apparent stablecoin exposure may be an unsecured claim rather than direct ownership of fiat-equivalent assets.

For a crypto-collateralized protocol, use collateralization rather than a simple 1:1 reserve ratio. DAI, which is migrating toward USDS, uses overcollateralization and requires a minimum 150% collateralization ratio for crypto vaults. The excess collateral absorbs crypto price volatility. The structure may also include real-world assets and USDC, which introduces separate market, custody, and issuer exposures.

The 150% ratio does not make the product comparable to a fiat-backed token at 100%. It reflects a different risk architecture.

Concentration can dominate the ratio

The reserve backing ratio is an aggregate. Aggregates conceal concentration.

A basket with 100 assets may have 95% of its value dependent on one issuer. A product with three stablecoins may have lower concentration if each token is backed by independent banks, custodians, and redemption systems.

Calculate concentration at several levels:

• largest token issuer;
• largest reserve bank;
• largest custodian;
• largest payment processor;
• largest market maker;
• largest maturity bucket;
• largest legal jurisdiction.

The largest exposure ratio is:

Largest exposure ÷ total reserve value

If a nested token has $1 billion in reserves and $700 million is USDC, its issuer concentration is 70%. If USDC and the top-level issuer use the same custody provider, effective operational concentration may be higher than 70%.

Cross-ownership also matters. One stablecoin may hold another as an investment or reserve asset. If token A backs token B and token B backs token C, the system can create circular exposure. The headline reserve total may count the same economic claim more than once across the structure.

A reserve model should remove duplicated claims and identify the ultimate fiat-equivalent asset. The chain ends only when the analysis reaches cash, bank deposits, Treasury instruments, or another independently verified eligible asset.

What to verify before treating a product as fully backed

Verification is a data exercise. The core questions are direct:

• What is the exact token liability at the reporting time?
• Which assets qualify as reserves?
• Are those assets segregated from corporate funds?
• Can the issuer redeem the underlying assets at par?
• What is the redemption window?
• What portion is immediately liquid?
• Which reserves are held as bank deposits?
• Are several assets dependent on the same bank?
• Are any assets pledged or restricted?
• Does the attestation cover the full reserve pool?
• Are valuation prices current?
• Are underlying stablecoins marked at one dollar regardless of secondary-market price?
• What happens if one reserve token trades below par?
• What happens if redemptions are suspended for 24 hours, three days, or longer?
• How much collateral remains after a 13% depeg in the largest underlying asset?

The last question should be quantified. If the answer is only a statement that reserves are “overcollateralized,” the risk model is incomplete.

A clean report should reconcile three totals:

1. Token liabilities

2. Gross reserve assets

3. Risk-adjusted available reserves

The first supports the denominator. The second supports the published balance sheet. The third supports a stress view. The gap between the second and third is the liquidity delta.

The systemic impact is determined by redemption design

A stablecoin ETF structure does not become safer merely because it contains multiple tokens. It becomes more complex.

A regulated framework can improve reserve eligibility, segregation, and disclosure. GENIUS Act requirements and MiCA’s HQLA and deposit provisions establish a clearer minimum standard. They do not eliminate bank-failure risk, transfer restrictions, maturity mismatch, or dependence on market infrastructure.

The practical hierarchy is clear:

1. Verify the legal reserve ratio.

2. Separate eligible assets from immediately available liquidity.

3. Apply look-through discounts to underlying stablecoins.

4. Measure issuer, bank, custodian, and jurisdiction concentration.

5. Stress the largest reserve asset for a depeg and redemption delay.

6. Remove duplicated or circular claims.

7. Compare risk-adjusted reserves with top-level token liabilities.

A 100% headline ratio is the starting point. It is not the conclusion.

For a single-issuer stablecoin, the central question is whether reserves can support redemptions at par. For a nested stablecoin ETF, the same question must be answered at every layer. The top-level token is only as liquid and collateralized as the reserve assets beneath it.

The systemic result is a transmission chain. A reserve bank failure can impair an underlying token. The underlying depeg can reduce the basket’s asset value. The basket impairment can weaken the top-level token. The final backing ratio depends on the quality, availability, and independence of every reserve claim in that chain.