MiCA’s Stablecoin Reserve Rule Turns Safety Into Bank Funding Risk

Europe is discovering that a stablecoin reserve can be safe for the token issuer and still be dangerous for the bank holding the money. That is the central problem behind a proposal from the European System of Central Banks to remove MiCA’s fixed bank deposit quota and replace it with a liquidity rule based on how quickly reserve assets mature.

The proposal sounds technical, but it changes where the risk sits. Under the current Markets in Crypto Assets framework, an issuer of an asset referenced token must keep at least 30 percent of its reserve assets in separate bank accounts. The share rises to 60 percent for issuers of significant asset referenced tokens. According to Reuters reporting on September 22, the European Central Bank and the national central banks of the European Union want those floors removed. Their alternative would require a minimum share of reserves to mature within one to five working days.

The argument is not that stablecoin reserves should become less liquid. It is that liquidity should be measured by the assets an issuer can convert into cash, rather than by the amount already placed at commercial banks. A large stablecoin issuer can look like a valuable depositor in normal conditions. In a redemption wave, the same issuer can become an unusually fast source of wholesale outflows. The bank receives concentrated money that behaves more like market funding than like a household savings account.

This creates a regulatory paradox. A high deposit quota makes the stablecoin easier to redeem because cash is already at a bank. Yet it can make the bank more exposed to the same redemption event because the issuer may withdraw billions in a short period. MiCA’s stablecoin reserve rule therefore does not eliminate liquidity risk. It chooses who absorbs it, when it appears and which balance sheet must be ready.

What the current rule is trying to protect

MiCA separates crypto assets into categories and gives stablecoin like instruments a dedicated framework. Asset referenced tokens track a basket or another reference value. Electronic money tokens generally reference a single official currency. Both depend on confidence that holders can redeem at the promised value. The official MiCA regulation therefore requires governance, disclosure, reserve management, custody and redemption protections that ordinary unbacked tokens do not have.

The deposit quota has a clear intuition. If some reserve assets are already cash at a credit institution, the issuer does not need to sell a bond before honoring every redemption. That reduces market execution risk, avoids depending entirely on securities settlement and gives supervisors a familiar pool of assets to inspect. It also limits the temptation to hold longer dated instruments whose yield is attractive but whose price can fall when rates rise.

The rule is especially understandable after repeated failures in crypto. Stablecoins have broken their pegs because of weak collateral, opaque relationships, operational failures and confidence shocks. Regulators do not want a European issuer to promise same day money while holding assets that take weeks to sell or cannot be valued in stressed markets. The deposit quota is a simple defense against that mismatch.

Simplicity, however, can hide concentration. A reserve manager does not distribute deposits across an unlimited number of banks. It must evaluate credit quality, operational capacity, legal segregation and payment connectivity. Large issuers are likely to use a relatively small group of major institutions. As issuance grows, each banking relationship can become material. The question shifts from whether the stablecoin has cash to whether the receiving bank can safely lose that cash on demand.

This distinction matters because a deposit is two things at once. It is an asset for the customer and a funding liability for the bank. The stablecoin issuer sees immediately available money. The bank sees funding that supports its own assets and liquidity planning. If the liability disappears quickly, the bank must replace the funding, sell liquid assets, borrow or reduce other uses of cash. The same euro cannot be viewed only from the issuer’s side of the ledger.

The stablecoin reserve rule can transform retail money into wholesale money

The central banks’ concern is that stablecoin growth could change the composition of bank funding. A household may move money from a current account into a euro stablecoin. The issuer then places part of the proceeds back into the banking system to satisfy MiCA. From a system wide perspective, the deposit has not necessarily vanished. It has changed owner and behavior.

A household deposit is not perfectly stable. Customers can transfer it at any time, and deposit flight can accelerate when confidence breaks. Yet millions of small accounts are often diversified by purpose and timing. Some pay salaries, some hold savings, some cover bills. A stablecoin issuer’s bank balance is different. It aggregates the decisions of many token holders into one institutional account. When redemptions rise, the issuer’s treasury function can draw that account rapidly and mechanically.

This is a form of liquidity compression. Many individual decisions arrive at the bank as one concentrated withdrawal. The bank may have no direct relationship with the underlying token holders and no ability to slow their blockchain transfers. It sees only the issuer’s demand for cash. A reserve rule intended to protect dispersed users has created a single large liability whose sensitivity can be higher than the deposits that funded it.

The mechanism resembles the disintermediation channel explored by the Federal Reserve Bank of New York. Its research on stablecoin disintermediation examines how stablecoins can erode deposit franchises and transmit liquidity stress into wholesale payment systems. The European proposal addresses a related problem from the reserve side. If issuers are required to return a large share of migrated deposits to banks, the banking system may retain the quantity of funding while losing its stability.

That is why the debate is not simply crypto against banks. The stablecoin and banking systems become connected through the reserve portfolio. A token redemption can trigger a bank deposit outflow. A bank concern can make holders question where reserves are held. A payment disruption can slow redemption even when the reserve assets are sound. Each sector can transmit stress to the other.

Block2Learn’s analysis of Bastion’s banking charter showed why stablecoin compliance is becoming infrastructure. The reserve rule reveals the next layer. Compliance is not only about proving that assets exist. It is about designing a balance sheet whose liquidity remains credible when every participant acts at once.

Cash is liquid, but the deposit is still a claim on a bank

Calling bank deposits cash can blur an important legal and economic distinction. A deposit at a commercial bank is a claim on that bank. It is usually available at par and on demand, but its safety depends on the institution, account structure, applicable protection and operational access. A central bank reserve is a different claim. A short dated government security is another asset again. Each can support liquidity, but each carries a different combination of credit, market, settlement and timing risk.

For a stablecoin issuer, commercial bank deposits have strong operational value. They connect directly to payment rails and redemption accounts. They can fund transfers without waiting for a security sale. They also create counterparty concentration. If one bank holds a large share of reserves, an operational outage or supervisory action can interrupt the stablecoin even when token demand is calm.

Short dated sovereign instruments distribute the risk differently. They can offer high credit quality and a liquid secondary market. They still need custody, valuation and settlement. A sale can occur at a small loss, especially when markets are stressed or a position is very large. A security that matures tomorrow may be more predictable than one that matures in a year, but it is not identical to an immediately usable bank balance.

The proposed maturity approach tries to measure this spectrum. An asset that matures within one working day can replenish cash soon without exposing the issuer to large duration risk. Assets maturing within five working days create a slightly longer bridge but can broaden the reserve portfolio. The exact minimum percentage will matter enormously. Reuters reported the maturity bands, but the policy debate has not yet produced a final rule in the public account. The proposal should therefore be read as a direction, not as adopted law.

Reserve design	Benefit for the issuer	Risk for the issuer	Risk transferred elsewhere
High commercial bank deposit share	Immediate redemption cash and familiar payment access	Bank concentration and operational dependence	Stablecoin redemptions can become concentrated bank funding outflows
Very short sovereign maturities	Predictable cash conversion and limited duration exposure	Settlement timing and market execution before maturity	Demand and liquidation pressure move toward bill markets and custodians
Broader liquid securities portfolio	Diversification and potentially higher return	More price volatility and liquidity uncertainty	Stress can reach dealers, repo markets and collateral channels
Maturity ladder across deposits and securities	Redemptions can be matched across several time windows	Requires forecasting, governance and frequent rebalancing	Risk is distributed but not removed

The table makes the core point visible. Every reserve design places pressure somewhere. Deposits place it on banks. Bills place it on government money markets and settlement. Longer assets place it on market liquidity. Diversification reduces dependence on one channel, but it cannot make a promise of immediate redemption costless.

A maturity ladder is better economics, but harder supervision

A fixed deposit percentage is easy to calculate. Supervisors can look at the reserve value, identify qualifying bank balances and test whether the ratio clears 30 or 60 percent. A maturity based framework requires more judgment. Authorities must define eligible assets, maturities, settlement assumptions, haircuts, concentration limits and the treatment of holidays. They must decide whether an asset that can be sold quickly is equivalent to one that contractually matures quickly.

That complexity can be worthwhile because it aligns the rule with the actual liability. Stablecoin redemptions do not arrive in one permanent proportion. They vary with market conditions, payment cycles, exchange activity and confidence. A reserve manager should maintain cash for ordinary flows, assets maturing soon for sustained outflows and a deeper pool of high quality liquid assets for extreme stress. This resembles liquidity management more than a static collateral box.

The risk is model dependence. An issuer may use historical redemption data to argue that only a small cash buffer is necessary. History can be misleading because a confidence event produces behavior not visible in normal samples. Supervisors will need stress scenarios that assume correlated redemptions, closed funding markets and delays in asset settlement. They will also need to inspect whether the issuer’s largest holders can redeem faster than retail users.

Haircuts are equally important. A government security worth 100 in calm conditions may realize slightly less if sold immediately in size. The issuer must still return 100 units of reference currency for 100 tokens if redemption at par is promised. A maturity ladder should therefore include excess value, not merely enough nominal assets. Liquidity and solvency are related but not interchangeable.

This is where the Financial Stability Board’s stablecoin recommendations remain useful. The FSB emphasizes effective stabilization, redemption rights, governance and cross border cooperation. A European maturity rule can improve the reserve structure, but it still needs those surrounding controls. An issuer with liquid assets and weak operations can fail to process redemptions. An issuer with good operations and ambiguous legal claims can still lose confidence.

Multi issuance turns a reserve question into a jurisdiction question

The deposit debate cannot be separated from multi issuance. Global stablecoin groups want tokens issued in different jurisdictions to function as one product. A dollar or euro token created by an EU entity may be treated as interchangeable with a token issued by an affiliate elsewhere. That improves network effects and user experience. It also complicates the question of which reserve supports which holder.

According to Reuters, the European central banks warned that such arrangements are currently prohibited under MiCA and would require strong safeguards and equivalence assessments if permitted later. Their concern is straightforward. If tokens are fungible across regions, redemptions may migrate toward the jurisdiction offering the clearest or fastest access. An EU reserve could face claims created elsewhere, while assets held elsewhere might not be available to EU holders at the moment of stress.

This is a reserve perimeter problem. Regulation assumes a defined issuer, defined liability and defined asset pool. Multi issuance can separate those elements. The customer sees one token. Supervisors see several legal entities, custodians and reserve accounts. The network routes the claim to whichever redemption path works. Unless the rules specify loss allocation and liquidity sharing, the most protected entity can become the preferred exit.

Circle’s Arc network demonstrates why global settlement platforms want a unified money asset. A stablecoin that behaves consistently across chains can reduce friction and deepen liquidity. Europe’s concern is not the convenience itself. It is whether legal and reserve consistency matches technical fungibility. A token can be interchangeable in software while remaining divided in law.

The solution will require more than reserve percentages. Authorities may need entity level liquidity pools, contractual support arrangements, limits on cross border redemptions or common supervision. They may also require clear disclosure that two visually identical tokens carry different legal claims. Each safeguard reduces the simplicity that made multi issuance attractive. That tension is structural and will not disappear through better terminology.

The banking system will not experience every stablecoin equally

Aggregate analysis can imply that stablecoins either drain banks or refill them. In practice, the distribution will be uneven. A household may move money from a regional bank to a stablecoin. The issuer may place reserves at a large international bank. Total deposits in the system change little, but funding moves from one institution to another. The regional bank loses a customer relationship and low cost funding. The reserve bank gains a concentrated institutional account.

This redistribution can strengthen the largest banks in calm conditions. They have the balance sheet, payment access and compliance systems needed to serve issuers. It can also create new concentration. A small number of institutions become critical to token redemption and receive funding that may leave quickly. The banks best able to attract stablecoin reserves are not necessarily the banks that lost the original retail deposits.

Interest economics matter too. Stablecoin issuers earn returns on reserve assets, while token holders may receive no direct yield. Bank deposits can pay less than short dated government instruments, especially when policy rates are high. A deposit quota therefore imposes an opportunity cost on the issuer. Replacing it with a maturity rule could allow more reserves to sit in bills, raising income. That can improve the issuer’s profitability, but it also increases the political importance of who receives the reserve yield.

A profitable issuer has more capacity to invest in compliance and infrastructure. It also has a stronger incentive to grow balances and defend market share. The reserve rule is therefore part of industrial policy. It influences which business models can compete, whether banks or asset managers capture the economics and how much scale is required to absorb compliance costs.

The Stablecore analysis examined the middleware that connects banks with token issuance. A maturity rule could expand that opportunity. Banks may supply payment accounts and redemption access, while asset managers and custodians manage the securities ladder. Stablecoin infrastructure becomes a chain of specialized services rather than one deposit account.

Enforcement is the condition that makes reserve reform credible

A better rule has limited value if noncompliant products continue serving European users. Reuters reported that the central banks also highlighted enforcement concerns after the June 2026 licensing deadline. The issue is competitive as well as prudential. A fully authorized issuer bears reserve, governance, disclosure and supervision costs. An offshore product that reaches the same customers without equivalent controls can offer better economics precisely because it does not carry those costs.

The European Securities and Markets Authority’s MiCA overview explains the common framework, while the European Banking Authority’s EUCLID register provides a route to checking regulated entities and information supplied by national authorities. These tools support transparency, but distribution happens through exchanges, wallets, decentralized protocols and direct transfers. A register cannot block a token by itself.

Enforcement therefore has several layers. Trading platforms can restrict products that lack required authorization. Banks can monitor reserve and settlement relationships. App providers can make issuer identity clearer. Supervisors can coordinate on marketing and access. None is perfect, especially when smart contracts are accessible without a centralized gate. The realistic objective is not to make noncompliant tokens technically impossible. It is to prevent them from receiving the same regulated distribution and credibility as compliant products.

This distinction is important for market competition. If Europe relaxes the deposit quota while strengthening maturity requirements, compliant issuers may gain flexibility. If enforcement remains weak, the reform may simply give every issuer a new argument while leaving the competitive imbalance intact. The policy package must combine better reserve design with a clearer perimeter.

Three scenarios for Europe’s reserve regime

Scenario one: maturity based liquidity becomes the new standard. Lawmakers remove the fixed deposit floors and require a substantial share of assets to mature within defined short windows. Concentration limits and stress tests accompany the change. Issuers diversify into short government securities, banks retain operational accounts, and reserve management becomes more sophisticated. This outcome reduces concentrated bank funding risk without weakening redemption quality.

Scenario two: the deposit quota survives with modifications. Policymakers accept the central banks’ diagnosis but prefer a simple floor. They lower the percentage, broaden eligible institutions or impose caps per bank. The rule remains easy to supervise, but issuers still concentrate meaningful funding in the banking sector. The system gains incremental resilience rather than a new architecture.

Scenario three: fragmentation overwhelms the reform. Europe changes the reserve rule while global multi issuance and offshore access remain unresolved. Compliant EU tokens hold carefully structured reserves, but users continue to favor larger international products whose legal claims are harder to map. The European regime becomes safer internally but less relevant commercially. In that case, the policy protects a small market rather than shaping the global one.

The evidence separating these scenarios will be visible. Watch the final definition of one day and five day assets, the minimum shares assigned to each bucket, concentration caps, stress assumptions and whether significant issuers face additional requirements. Then watch the market response: reserve composition, bank counterparties, bill holdings, redemption speed and the growth of euro denominated tokens.

What would invalidate the central banks’ case

The proposal rests on the belief that stablecoin issuer deposits are less stable than the retail money they may replace. That should be tested, not accepted as a permanent truth. If data show that issuer balances remain stable through redemption waves because outflows are offset by new inflows or securities maturities, the bank funding concern would be weaker. If banks fully match those deposits with central bank reserves or equally liquid assets, the transmission risk would also fall.

The case would weaken if a maturity based portfolio proves slower to monetize than deposits during real stress. Settlement failures, custody constraints or disorderly bill sales could show that contractual maturity is an incomplete proxy for usable liquidity. A reserve that matures tomorrow is helpful only if tomorrow’s proceeds reach the redemption account without interruption.

Conversely, the case strengthens if stablecoin growth causes measurable shifts from diversified retail accounts into a few volatile institutional balances. It also strengthens if banks price those deposits as short term funding, maintain unusually large liquidity buffers against them or limit issuer balances. Supervisory data on concentration and outflow behavior will matter more than abstract claims from either industry.

The most revealing test may be commercial behavior. If banks want the deposits only when they can reprice or limit them quickly, they are signaling that the funding is not equivalent to ordinary retail money. If issuers consistently prefer bills despite lower operational convenience, they are signaling that deposit concentration is a real cost. Market choices can expose risks before public statistics do.

Stablecoin safety is a system design problem

Europe’s reserve debate corrects a common mistake in digital asset regulation: examining the token in isolation. A stablecoin connects holders, an issuer, banks, custodians, securities markets and payment systems. Making one link safer can load more pressure onto another. The deposit quota improves immediate access to cash, but it can turn retail funding into a concentrated institutional liability. A maturity rule diversifies that pressure, but it introduces more valuation and settlement complexity.

The right objective is not the largest possible cash balance. It is reliable redemption without creating a fragile funding channel elsewhere. That requires a ladder of usable assets, diversification across banks and custodians, conservative haircuts, realistic stress tests and clear legal claims. It also requires enforcement strong enough that safer issuers are not undercut by products operating outside the perimeter.

The debate also clarifies the relationship between private tokens and public money. The ECB’s Pontes infrastructure is bringing central bank settlement closer to tokenized assets. Stablecoins serve a different function, especially in continuous and cross border markets. Their reserves nevertheless end in the traditional financial system. The closer tokens move to mainstream payments, the more their design becomes a question of banking and money market structure.

For readers following this transition, the Block2Learn Learning Path offers a useful method: trace the liability, identify the asset behind it, then ask who must provide liquidity when confidence changes. That sequence reveals why a deposit is not merely idle cash and why a reserve rule can influence institutions far beyond crypto.

MiCA’s stablecoin reserve rule was built to make redemption credible. The central banks are now arguing that credibility should come from maturity and diversification rather than a fixed deposit quota. Their proposal does not make stablecoins risk free. It recognizes that a promise of par value is supported by a chain of balance sheets, and that safety depends on whether the entire chain can withstand the same withdrawal at the same time.

Sources: Reuters, September 22, 2026; Regulation (EU) 2023/1114; ESMA MiCA overview; EBA EUCLID register; Federal Reserve Bank of New York Staff Report 1185; Financial Stability Board recommendations.