The Singleness of Money: An Institutional Achievement Stablecoins Haven't Passed

"A euro is always the same euro, regardless of which bank it came from."

This sentence is so obvious that most people never think about it. You transfer money between banks every month — Bank A to Bank B — and the value is always the same. No discount, no exchange rate, no questions asked.

This is not a technical inevitability. It is the single hardest institutional achievement in modern monetary history. And it is the one thing stablecoins have not yet figured out.

1. The Two-Tier Architecture

To understand singleness, you first need to understand how modern money is created.

The monetary system has two tiers:

• Tier 1: Central bank money — physical cash you hold in your wallet, and reserves that only commercial banks can hold at the central bank
• Tier 2: Commercial bank money — the digital balances in your bank account. These are not central bank money. They are private liabilities of commercial banks, created when banks make loans

This surprises most people. They assume their bank balance is "government money." It isn't. In a fractional-reserve system, banks create deposits through lending. For every dollar of reserves created by the central bank, the banking system can create several dollars of deposits.

So here's the problem: if my money is a liability of Bank A, and your money is a liability of Bank B, why are both worth exactly the same amount?

The answer is the central bank.

2. The Central Bank as Trustee

The Bank for International Settlements (BIS) describes the central bank as "the system's trustee: the entity around which all other balance sheets can safely revolve." This role has three facets:

• Stabilising the unit of account — monetary policy maintains price stability
• Guaranteeing par settlement — operating and overseeing payment systems so that commercial bank deposits are always convertible to reserves at face value
• Supplying liquidity on demand — from intraday credit within RTGS systems, to regular open market operations, to emergency lender-of-last-resort facilities

These functions rest on a balance sheet backed by the sovereign's taxing power, and institutional independence from short-term political pressures.

The BIS definition is precise:

"The singleness of money, under which claims denominated in that unit are redeemable at par with central bank money with finality."

Together with coordination on a common unit of account, these two properties render money an "information-insensitive asset" that can pass from hand to hand with no questions asked.

3. The Anti-Jamming Mechanism

Singleness depends on something most people never see: elastic liquidity supply.

Economic activity is not smooth. Tax payment days, quarter-end balance sheet adjustments, and sudden shifts in risk appetite create spikes in demand for settlement balances. If the supply of central bank reserves were rigid, payment systems would jam.

The BIS warns directly:

"If the supply of those balances were rigid, payments would jam and an otherwise solvent liquidity shock could mutate into a solvency crisis."

Central banks prevent this through a multi-layer elasticity framework:

Because every solvent commercial bank can always replenish its reserve balance through one of these channels, deposits at any bank remain redeemable at par at all times. This is the anti-jamming mechanism. It is invisible, silent, and essential.

4. This Wasn't Always True: The Free Banking Era (1837–1863)

Singleness of money is not a natural feature of markets. It was achieved only after painful experiments. The most vivid counterexample is America's Free Banking Era.

Between 1837 and 1863, any bank could issue its own banknotes under state charters. The result was monetary chaos:

• Different banks' notes traded at different discounts against par — a bank in Philadelphia might trade at 98¢ on the dollar, while one in rural Michigan might trade at 85¢
• When a bank failed, its notes became worthless paper
• Merchants needed subscription guides like the Bank Note Detector — a handbook hundreds of pages long listing current trading discounts for thousands of different banknote types

This was not a monetary system. It was a transaction-cost nightmare. The author of the Bank Note Detector, John Thompson, wrote in its preface in 1839:

"A person might travel hundreds of miles and suffer much inconvenience before he could find a person willing to take his bank notes at par."

The solution — a unified national currency, centralised settlement through the National Banking Act (1863), and eventually federal deposit insurance (1933) — took decades of legislation, crisis response, and institutional innovation.

The lesson: every monetary system that lacks institutional guarantees of par exchange eventually fragments.

5. The Three-Layer Challenge from Stablecoins

The BIS 2026 Annual Economic Report assesses stablecoins against the singleness standard and identifies three fundamental deficiencies.

Layer 1: No Settlement on the Central Bank's Balance Sheet

Stablecoin transfers settle neither directly nor indirectly on central bank balance sheets. Whether USDC or USDT, the "$1 = $1" promise is not backed by a central bank guarantee — it is the issuer's redemption commitment.

The BIS describes this bluntly:

"Current stablecoin designs resemble ETF shares rather than a means of payment."

Secondary market data confirms this: stablecoin prices persistently deviate from par (even if moderately), and redemption frictions are well-documented — both Tether and Circle have paused redemptions in past stress events.

Layer 2: Cross-Chain Fragmentation

The same stablecoin on different blockchains is not the same money. USDC on Ethereum is not USDC on Solana — they run on independent ledgers with no native communication. In stress periods, prices across chains have diverged materially.

The BIS states this "undermines the singleness of money."

Layer 3: No Liquidity Elasticity

When a wave of depositors demands redemption simultaneously, a bank goes to the central bank to replenish liquidity. A stablecoin issuer cannot. Its liquidity depends entirely on finding buyers for its reserve assets in public markets — at the worst possible time.

The Central Bank of Ireland's plumbing-level analysis (Dr Rhys Bidder, 2026 Q1) diagnoses the root cause:

"Stablecoins exhibit random deviations from par (violations of singleness) because secondary market transactions involving them are not hardwired to the reserves system in the same way."

The asymmetry is structural: bank deposits are account-based monies that settle through coordinated adjustments in reserves at RTGS; stablecoins are bearer assets that settle purely on-chain. Even if a stablecoin is 100% reserve-backed, the backing does not equal settlement. The second is what hardwires par — and stablecoins operate without it.

The stablecoin ecosystem has no lender of last resort. BIS's stress scenarios show that mass redemptions force fire sales that transmit market pressure through safe-asset markets.

6. Stablecoins vs Bank Deposits: A Settlement Taxonomy

7. The Core Debate: Is Money Code or Institution?

This question cuts to the heart of digital money policy:

Is money a piece of code, or is it an institution?

The pro-stablecoin camp argues: private-sector innovation is faster, more competitive, and more resilient. A smart contract on a public blockchain is transparent, immutable, and accessible to anyone — no bank account required. The "stablecoin sandwich" (fiat → on-chain transfer → fiat) already replaces an entire correspondent banking chain with a single ledger.

The pro-central-bank camp counters: money is fundamentally an institutional achievement. Singleness is not a property of code. It is the product of centuries of design — central bank settlement infrastructure, deposit insurance, lender of last resort facilities, prudential regulation, and legal frameworks for settlement finality. The U.S. Free Banking Era was a natural experiment in what happens without these institutions.

The BIS's position is pragmatic: not to eliminate stablecoins, but to bring tokenisation's advantages into the two-tier system. The vehicle is the unified ledger — integrating tokenised central bank reserves, commercial bank money, and supervised private monies on interoperable platforms.

The Eurosystem is working toward this through two tracks:

• Pontes ("bridges") — interoperability between existing TARGET services and DLT systems
• Appia — a deeper, integrated DLT solution for the longer term

8. The Deeper Question

If the consensus is "institutional absorption of code," a more uncomfortable question emerges: who controls the absorption?

The three major models differ sharply:

The US allows relatively independent code (self-custody, permissionless transactions). Europe insists code binds to institutional identity (MiCA's EMT/ART classification requires different compliance levels). China eliminates the gap entirely — the code is the institution.

The question is not whether institutions will absorb code. They will. The question is how much autonomy the code layer retains.

Conclusion

Singleness of money is the foundational property that makes modern monetary systems work. It is not natural. It was built over centuries — through the National Banking Act, the Federal Reserve System, federal deposit insurance, international settlement standards, and lender-of-last-resort doctrines.

Stablecoins have not replicated it. They may not need to — there are use cases where slight deviations from par are acceptable, and BIS acknowledges that tokenisation can bring genuine benefits to the two-tier system. But anyone who claims stablecoins solve the same problem as the two-tier system is skipping a century of institutional history.

The BIS closes its assessment with a warning:

"Any future monetary arrangement — whether it entails incremental improvements or a leap into tokenised finance — must respect this legacy, or else be prepared to relearn the old lessons."

Further Reading

• The Singleness of Money — Full Wiki Entry
• BIS Annual Economic Report 2026, Chapter III: Anchoring Trust in Money
• Money and Payments Infrastructure — Central Bank of Ireland (Bidder, 2026)
• US Stablecoins, Europe's Digital Euro, and China's e-CNY: A Tri-Polar Battle