Safe haven currency

An informal label for a currency that has historically strengthened during periods of market stress, whatever the source of the stress. Nobody maintains the list. The currencies that end up on it share recognisable features: a deep and liquid market in the government's own debt, an open capital account, a long record of honouring obligations, and a large stock of the currency already held in reserves and in contracts around the world.

The behaviour is mechanical rather than sentimental, which is why the label survives. The dollar is the currency most cross border debt and most commodity invoicing is written in, so a scramble for funding is a scramble for dollars. The yen has for long stretches been the cheaper side of financing positions, so an unwinding of those positions is itself yen buying. The franc is supported by a large external asset position and a small, conservatively financed domestic economy. In each case the flow arrives because of how the currency is used, not because anyone judged it safe that morning.

Two things are commonly misread. The label describes past episodes rather than a property that holds in the next one: the dollar has strengthened during shocks that originated inside the United States, which is difficult to square with a plain reading of the word safe. And haven behaviour has been interrupted by policy, notably where an authority has acted to prevent its own currency appreciating. A correlation measured across a decade can therefore describe a relationship that is absent in the week it is relied on, and practitioners disagree about which currencies, and whether gold, deserve the description now.