Hard currency

No authority publishes a list. The label describes a bundle of properties: convertibility without exchange controls, a market deep enough that large amounts change hands without moving the rate far, an issuing country with credible institutions and a record of contained inflation, and a place in the reserves other central banks hold. The currencies conventionally counted are the US dollar, the euro, the yen, sterling, the Swiss franc and the Canadian and Australian dollars.

Membership is inferred rather than granted, from turnover in the global market, from the legal position on moving money in and out, and from the published composition of official reserves. The opposite label, soft currency, describes the mirror image: restricted convertibility, thin trading, wide quoted prices and a history of abrupt official revaluation. Between the two sit the currencies usually described as emerging market currencies, which are convertible in practice but neither deep nor uniformly accepted.

The word hard misleads more readers than any other part of the definition. It refers to acceptance and convertibility, not to a stable exchange rate. A hard currency floats, and floating currencies move sharply against one another. Practitioners also disagree about whether hard currency and safe haven currency describe the same set. The overlap is partial: safe haven behaviour is observed during specific stress episodes and shifts between episodes, while hardness is a structural property that changes over decades.