Why a Weaker Effect of Exchange Rates on Net Exports Doesn’t Weaken the Power of Monetary Policy

Miles Kimball
Jan 5, 2016 · 4 min read

On New Year’s Day, 2016, I tweeted:

Let me explain at greater length. Paul Hannon is right in his Wall Street Journal article “Why Weak Currencies Have a Smaller Effect on Exports” in writing:

When a country loosens its monetary policy, interest rates fall and investors tend to pull their money out in search of higher yields elsewhere, pushing down the currency’s value.

And the article goes on to make a very interesting point about how global supply chains might be blunting the effect of a given change in the exchange rate on net exports:

Measuring the impact of global supply chains on trade flows is the task of a project undertaken by the Organization for Economic Cooperation and Development and the World Trade Organization. …

Economists at the International Monetary Fund and the World Bank have used those measures to assess whether currency movements have the same impact they once did on exports and imports. They found that the effect has in fact reduced over time, by as much as 30% in some countries.

But Paul Hannon’s overall subtext that this weakens the power of monetary policy is wrong. Start with the basic accounting identity of international finance that Paul alludes to and that I discuss in detail in my post “International Finance: A Primer”: the provision of domestic currency to those outside one’s currency zone through net capital outflows NCO (and through other channels as remittances of foreigners sending money to their families back home) must lead to an increase in net exports NX of equal magnitude. (Also see my column “How Increasing Retirement Saving Could Give America More Balanced Trade.”) The only wiggle room in this statement is that for whatever period of time someone abroad are willing to temporarily hold a growing pile of our domestic currency provided by intentional purchases of foreign assets that counts as an unintentional capital flow in the reverse direction. As soon as they want to unload our currency, our currency will make its way back home one way or another. (If people abroad decided to hold a pile of our currency more permanently, that rightly counts as an intentional capital flow in the reverse direction, canceling out all or part of the initial capital flow.)

Of course, the way the price system guarantees the return home of domestic currency that is unwanted abroad is through exchange rate movements. But the logic here means that exchange rates move as much as it takes to bring about the return of domestic currency that is unwanted abroad. So an increase in intentional capital outflow of $1 creates a $1 increase in net exports over whatever horizon it takes for domestic currency that is unwanted abroad to make its way back home. The relevant horizon is not instantaneous, but foreigners are unlikely to be willing to hold piles of unwanted domestic currency for very long. (Of course, governments sometimes choose to override this part of the prices system by imposing fixed exchange rates. Fixed exchange rates work by having the government equal and opposite capital flows to neutralize the effect of changes in intentional private capital flows on exchange rates.)

When the central bank cuts interest rates, the initial step in affecting international finance is in generating net capital flows of a certain size as domestic investors search for higher returns abroad, and potential foreign investors think better of sending their funds to a low-interest-rate country. These capital flows then have a 1-for-1 effect on net exports after the recycling of currency described above, regardless of the elasticity of net exports with respect to the exchange rate.

If net exports are relatively insensitive to the exchange rate, the exchange rate will simply move more. Indeed, many casual observers are struck by the large fluctuations often seen in the exchange rate. Large fluctuations in the exchange rate are exactly what one should expect if net exports are relatively insensitive to movements in the exchange rate, as I wrote about in “The J Curve.”

What would affect the potency of monetary policy is if the effect of a given movement in interest rates on international capital flows went down. But I don’t know of anyone claiming that is the case. (What I do hear a lot of is the speculation that cutting interest rates into the negative region would be especially salient to investors and so might have a particularly large effect on international capital flows — which would then increase the potency of monetary policy.)

One particular area where the discussion above matters is in assessing Japanese monetary policy. How much stimulus the Bank of Japan has achieved through the international finance channel is much better measured by the size of the international capital flows generated than by the size of the exchange rate movements that result. Because overall Japanese investors have a particularly strong home-bias, the effect of monetary policy on international capital flows may be weaker than in most other countries. But it is factors such as home-bias that matter for the contribution of international finance to the potency of monetary policy, not the elasticity of net exports with respect to the exchange rate. (On Japanese monetary policy, also see “Is the Bank of Japan Succeeding in Its Goal of Raising Inflation?”, “Japan Should Be Trying Out a Next Generation Monetary Policy” and “QE May or May Not Work for Japan; Deep Negative Interest Rates Are the Surefire Way for Japan to Escape Secular Stagnation.”)

To repeat: Weak effects of a given size of exchange rate movement on net exports does not blunt the effects of monetary policy because exchange rates do whatever it takes to make net exports equal to net international capital flows.

Miles Kimball

Written by

University of Michigan Professor of Economics and Survey Research. Quartz Columnist and Independent Blogger about Economics, Politics and Religion.

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