Why did the dollar rise with Trump but the pound fall with Brexit?

If you are part of the conventional liberal “elite” like me, 2016 has been marked by two colossal acts of democratic self-harm: Brexit and the election of Donald Trump. It is easy to understand why the pound sunk after Brexit. By why has the US dollar being doing so well after the election of Donald Trump as president? It is a useful lesson in macroeconomics.

The first thing to say, though, is that the way most of the media cover such market movements is unhelpful. They talk of sentiment and emotional judgements made by anthropomorphised “markets”. These may provide a satisfactory story line for a journalist, but they yield no real insight and no predictive power. They are simply projections onto past events. But very often, and this is no exception, far more satisfactory explanations are available, based on the way money flows through economies and financial markets.

Take Brexit. The obvious explanation is that markets (sticking with the anthropomorphism for now) take a dim view of Britain’s prospects amid the confusion and uncertainty thrown up by Brexit. But by itself that explanation is inadequate. The fall in Sterling was not matched by falls in stock markets (after an initial wobble) and other markets which also depend on future economic prospects. In fact there seems to be much more of a wait-and-see approach by the people and institutions who set market prices.

But wait-and-see is not so neutral. The UK runs a substantial current account deficit (5.7% of GDP according to the Economist, the highest of the 43 countries in its data table – and the second largest in money terms, at nearly $150bn in the last year). That means that the country is consuming much more than it is producing, which in turn means that the country is spending more pounds than it is getting back from exports, etc (or spending more foreign currency on imports than it is getting from exports). This deficit must be made up from the capital account – by investors buying UK assets of one sort or another (or Britons selling off foreign assets). Wait-and-see means that foreigners are more likely to defer making investments, which reduces the demand for Sterling on capital markets, causing its price to fall. This makes UK assets more attractive, UK exports more competitive and imports less attractive. All perfectly textbook.

So, what about the US? This country has a current account deficit too (2.6% of GDP which is $488bn in money terms, the largest current account balance in any direction by some margin, in the Economist table). Surely there is a lot of waiting and seeing to be done here, as Mr Trump’s policies, shall we say, lack clarity? But there are a number of differences with the UK. The first of these is that the US is an economic superpower, which dominates global financial markets, with the dollar used as the top reserve currency. It is much easier for the country to draw in investment that the aging middle-ranking country that is the UK. It has much more secure access to liquid, short-term funding. And with a huge domestic market the outlook for its businesses look less precarious than that for British ones.

But the most important difference is that, for all Mr Trump’s lack of clarity, what is known about him, and the Republicans who control Congress, points to a loosening of fiscal policy. This mainly takes the form of tax cuts. This increases the demand for dollars, because it will increase spending in the US domestic economy. Exactly how remains to be seen. On one version US corporations will repatriate foreign profits and invest in infrastructure. This is all uncertain – but Mr Trump and the Republicans in Congress certainly agree on tax cuts, especially for the wealthiest. And this happens at a time when most people are convinced that the US is running at close to capacity – so there is no question of fiscal laxity being complemented by monetary laxity, which would allow the increased demand for dollars to be met by extra supply. Indeed the Federal Reserve is in the process of tightening policy, and increased interest rates this month.

This economic dynamic is often not appreciated – that in a world of freely floating currencies and open capital markets, loose fiscal policy leads to an appreciation of the currency. But there are plenty of examples if you look for them. When Germany unified in the early 1990s, it involved a considerable relaxation of fiscal policy – which caused the Mark to appreciate, and a crisis in the European Exchange Rate Mechanism in 1992 that forced Sterling to leave, shredding the credibility of John Major’s Conservative Government. My Economics lecturer at UCL used the British government of the mid-noughties as another example – the government ran a larger budget deficit than was warranted at that point in the economic cycle, at a time when banking laxity had already led to excess demand in the economy.

The effect of fiscal policy on a floating currency is part of what is known by economists as the Mundell-Fleming model, proposed independently by economists Robert Mundell and Marcus Fleming, leading theorists of floating currencies. It is one of the reasons that floating currencies are not quite the free lunch suggested by many Anglo-Saxon commentators. It means that a floating rate tends to neutralise fiscal policy (just as a fixed rate neutralises monetary policy). As a currency appreciates, the current account reduces (or deficit gets larger), and any increase in aggregate demand is lost across the world economy. Unless monetary policy operates in the same direction (including “printing money” to monetise the budget deficit), in which case you are in effect operating a managed exchange rate policy. This often ends in inflation or default.

This points to one of the tensions in Mr Trump’s economic policy. Fiscal laxity will lead to a widening trade deficit – exactly the opposite to what he promised on campaign. That will tend to force him into protectionist policies, which in turn could create a doom-loop of global proportions. Many believe that we have the makings of another global financial crisis, especially given developments in the Chinese economy – for example read this from Yanis Varoufakis.

But another tension could be that Mr Trump’s fiscal stimulus proves ineffective. The rich people and corporations that benefit from the tax cuts save most of their winnings; planned infrastructure spending is lost to political friction; and Congress insists on dismantling the social safety net, especially Medicare, sucking demand out of the system by hitting the less well-off. That would mean that growth is disappointing, breaching another Trump campaign promise.

But that’s in the future. For now participants in the financial markets are readying themselves for more demand for dollars, and weaker demand for pounds. They aren’t taking a view on the wisdom or otherwise of either Brexit or the new US regime.