In the previous post, I suggested that we should think of the various trade and financial flows in the balance of payments as evolving more or less independently, with imbalances between them normally accommodated by passive buffers rather than being closed by any kind of price adjustment. In that post I focused on the prewar gold standard. Here is a more recent example of what I’m talking about.

From 2012 to 2013 there was a general “risk on” shift in financial markets, with fears of a new crisis receding and investors focusing more on yield and less on safety and liquidity. In a risk-off environment investors prefer the safety of US assets even if yields are very low; in a risk-on environment, as we were moving toward in 2013, they prefer higher-yielding non-US assets.

Now, how was this shift in asset demand accommodated in the balance of payments? Orthodox theory suggests that there should be some offsetting change in interest rates and/or exchange rate expectations to keep demand for US and non-US assets balanced. But this didn’t happen — interest rate differentials didn’t close, and “risk-on” is associated with a falling rather than a rising dollar. And in fact, there was a large net outflow of portfolio investment: Net acquisition of foreign assets was $250 billion higher in 2013 than 2012, and net foreign acquisition of US assets by foreigners was $250 billion lower. Orthodox theory also says that if there is a net shift in investment flows, there should be an offsetting change in the current account. But the US current account shifted only $60 billion toward surplus, compared with the $500 billion net shift in portfolio flows. In a country with a fixed exchange rate, we would expect the remaining portfolio outflow to be accommodated by a fall in foreign exchange reserves. but of course the dollar floats, and the Fed does not hold significant reserves.

In fact, the entire shift was accommodated within the US banking system, most importantly by a rise in foreign-held deposits of $400 billion. Now this is an increase in US foreign liabilities, but it does not reflect a decision by anyone to borrow from abroad. It simply reflects the mechanics of international financial transactions. When an American spends money to purchase a foreign asset, the “money” they are using is a deposit at an American bank. When the asset is purchased, that deposit is transferred to the foreign asset-seller (or some intermediary), turning the deposit into a foreign liability of the bank. So the shift of portfolio investment out of the US does not require any change in prices (or incomes) to generate an offsetting flow into the US. The foreign liabilities that finance the purchase of foreign assets are generated mechanically in the course of the transaction itself.

Eventually, the effort to close out this residual long dollar position might produce downward pressure on the value of the dollar. And if the dollar does depreciate, that may increase demand for other US assets or for US exports sufficient to absorb the deposits. But there is no guarantee that either of these things will happen. And certainly they will not happen quickly. What we know for sure is that buffering within the banking system can offset quite large flows for substantial periods of time — in this case, a shift in portfolio flows of a couple percent of GDP sustained over a year. It might be that, with sufficient time, net sales of US assets might be large enough to push their price down, raising the yield enough to compensate for the lower safety premium. Or it might be that the downward pressure on the dollar will eventually lead to a big enough depreciation to raise US net exports enough to balance the portfolio outflow — but this will be a very long process, if it happens at all. It’s quite likely the portfolio will reverse for its own reasons (like a shift back toward “risk off”) before these adjustments even get started. Alternatively, liquidity constraints within the banking system may exhaust its buffering capacity before any other adjustment mechanism comes into play, requiring active intervention by the state or a catastrophic adjustment of the current account. (Presumably not in the case of the US, but often enough elsewhere.)

In practice, where we see payments balance maintained smoothly, it’s more likely because the underlying patterns of trade and investment are balanced and stable enough to not strain the buffering capacity of the banking system, rather than thanks to the operation of any adjustment mechanism.