For a depositor during a panic, central bank money can look safer than a commercial-bank balance. Make that public money digital and instantly accessible, and the journey from one to the other may become much faster. This was the mechanism behind Jens Weidmann’s 2019 warning—not a blanket claim that every central bank digital currency would destabilize finance.
The balance-sheet question behind a “digital bank run”
Commercial banks use deposits as an important source of funding. If households and companies could exchange large deposit balances for retail CBDC within seconds, banks under stress might need replacement funding, reduce lending or seek central-bank liquidity. A safe asset for an individual can therefore alter risk at system level when many people move together.
The Bundesbank’s account of its May 2019 symposium said a broadly available CBDC could change banking business models and financial intermediation. In a crisis, an additional liquid and secure alternative might allow a flight to safety—or a bank run—to proceed faster and on a larger scale.
Nothing in that reasoning makes the outcome automatic. The pressure depends on who can hold the currency, whether balances earn interest, how much can be held, how transfers work and what role commercial intermediaries retain.
CBDC and cryptocurrency are not interchangeable labels
| Feature | Retail CBDC | Decentralized crypto-asset |
|---|---|---|
| Issuer or liability | Direct liability of a central bank | No central-bank liability |
| Monetary role | Digital form of sovereign money | Privately held network asset |
| Governance | Public mandate and legal framework | Protocol and participant governance |
| Bank-run channel | Deposits may move into public money | Movement is into a risky private asset |
The old description “cryptocurrencies issued by central banks” hides these differences. A CBDC can use centralized infrastructure and need not inherit the issuance model, volatility or consensus mechanism of Bitcoin. The relevant stability question is the public’s access to a central-bank claim, not whether a fashionable technology label applies.
How later European work treated the risk
Subsequent digital-euro analysis turned the warning into design work. The European Central Bank’s project material discusses safeguards and the role of supervised intermediaries while making clear that preparatory work is not itself a final issuance decision.
Possible controls include holding limits, non-remuneration or tiered remuneration and arrangements that move excess balances back to linked bank accounts. Each choice also has costs: a currency made too restrictive may be unattractive, while one designed as the safest and most rewarding store of value could compete strongly with deposits.
Timing changes the calculation as well. Gradual introduction can reveal how households use the instrument before limits are widened. Crisis behavior cannot be inferred solely from ordinary retail payments, however, because demand for safety may jump precisely when confidence in individual banks falls. Stress testing therefore has to consider normal adoption and exceptional outflows.
Weidmann’s intervention is therefore best read as a constraint for designers. Retail CBDC should be useful enough to serve a public purpose without becoming an unlimited escape route from the banking system during stress. Whether that balance can be achieved is an empirical and institutional question, not a foregone conclusion embedded in digital money itself.
