I have a few thoughts about the J-curve in International Finance. The idea is that the medium-run supply and demand elasticities with respect to the exchange rate are higher than the short-run elasticities. So in an era of deprecations within a fixed-exchange-rate regime, that would mean that the quantities of exports and imports would at first respond less than the prices, but later on the quantities would move more, so the value of net exports would go down right after the depreciation, but later go up.  

Here is my question. Think of a flexible-exchange-rate regime in which capital flows are determined by what people want to do with their portfolios, as I describe in my post “International Finance.”  Then, if the domestic central bank cuts interest rates and people want to shift toward foreign assets, that intentional capital outflow plus any unintentional capital flow plus any other flows of funds across borders that are not associated with the purchase of goods and services internationally (such as remittances) has to equal net exports. There might be a short time when unintentional capital flows cancel out some of the intentional flows, but it seems to me that in a flexible-exchange-rate regime, pretty soon net exports have to match those intentional capital flows. So the prediction would be that the low short-run elasticities of imports and exports would show up in a bigger movement in the exchange rate in the short run than in the medium run. Of course there are some risky arbitrage possibilities with that kind of movement. But do we see such a quickly-reverting pattern for exchange rates anyway? It certainly seems like exchange rates move an awful lot in the short run.

An interesting case is when the short-run price elasticity of net exports is less than one. (Note how different that is from gross exports or gross imports having an price elasticity less than one.) If depreciation means less of the local currency gets spent on net exports, then net exports can’t equilibrate with a fixed level of capital outflow. What I think would have to happen in the short run is that the initial capital outflow causes a drastic enough decline in the value of the domestic currency that the financial market rethinks the initial intentional capital outflow. That is, someone needs to see the domestic currency as so cheap they want to move their portfolio into it. It may take a very large depreciation before that is the case. Does that story make sense?