The term ‘contagion’ is used quite a bit in the financial press, but what does it actually mean? There are at least three very different types of contagion, each with its own policy implications:
1. An economic crisis in one country might reveal a weakness that was not previously apparent to the international investment community. Thus in the late 1990s, the gradual rise of China and the strengthening US dollar was slowly weakening the position of export-oriented nations in Southeast Asia, which had fixed their currencies to the US dollar and also accumulated dollar-denominated debts. When Thailand got into trouble in mid-1997, investors looked around and noticed similarities in places like Malaysia and Indonesia. It wasn’t so much that Thailand directly caused problems in those countries (in the way a US recession might directly cause problems for Canada); rather it revealed weaknesses that were already there.
2. A financial crisis in a big country might depress the global Wicksellian equilibrium real interest rate. For example, the US housing bust and banking crisis of 2007-08 triggered a global recession. By itself, this doesn’t necessarily cause problems in other countries. But if the foreign country is already at the zero bound (Japan), or if the foreign central bank is too slow to cut interest rates (ECB), then a lower global equilibrium interest rate might lead to tighter money in other countries. Here I would say that the US triggered the Great Recession, but the Fed, ECB and BOJ jointly caused the Great Recession.
Similarly, under an international gold standard, the hoarding of gold in one country can depress nominal spending in other countries. Indeed gold hoarding by the US and France was a principal cause of the Great Depression.
3. A financial crisis in one country can affect other nations if they are linked via a fixed exchange rate regime or a single currency. Consider Greece, which comprises less than 2% of eurozone GDP. Fears that Greece might have to leave the eurozone caused significant stress in other Mediterranean nations. If one country were to exit, investors might expect this to lead to an eventual breakup of the entire eurozone. That would trigger a banking crisis, and would also lead major debtor nations such as Italy to default on their huge public debts. This is why a small country like Greece could have such a big impact on eurozone asset markets; investors feared that a Grexit would destroy the eurozone.
So far, Turkey looks like it fits the “reveal” template best. The greater the extent to which Turkey is viewed as a special case reflecting local conditions, the smaller the contagion effect. If Turkey becomes seen as emblematic of much of the developing world, then contagion is more likely.