What do you do if you are an emerging market facing massive capital inflows that risk inflating the next round of bubbles? Brazil’s decision to impose a 2 per cent tax on short-term flows has been widely criticised and with good reason. Companies and investors will structure transactions that bypass the tax. The 2 per cent surcharge is anyway small relative, for instance, to the volatility in Brazil’s Real and may not provide much of a deterrence to a perceived one-way bet.

The problem is that while I think the inflow tax will not work, I struggle to see what the alternatives are. One way to prevent a domestic asset price bubble is to allow the currency to rise sharply, making domestic assets more expensive to foreigners and creating two-way currency risk in future. But this is very hard to do when other big emerging market exporters such as China are keeping their exchange rates pegged to the dollar. Read more