Another Nail in the Global Saving Glut Coffin

David Laibson and Johanna Mollerstrom have a new paper--see here for a shorter version--that further undermines the popular global saving glut theory (GSG). According to the GSG theory there was an increase in global savings beginning in the mid-to-late 1990s that originated in Asia and to a lesser extent in the oil-exporting countries. This surge in global savings found its way into the United States via large current account deficits that, in turn, created the asset bubbles of the past decade. Laibson and Mollerstrom argue the GSG theory has the causality backwards: the asset bubbles in the advanced economies came first and spurred consumers to go on a consumption binge. That consumption binge, in turn, was financed by savings from abroad. The smoking gun in their story is that had the foreign funding been truly exogenous then there would have been a far larger investment boom given the amount of foreign lending. Instead, there was a consumption boom which is more consistent with causality starting from an asset bubble. Their paper adds to their growing chorus of SGT skeptics including Menzie Chinn, Maurice Obstfeldt andKenneth Rogoff, Guillermo Calvo, and myself.

Interestingly, Laibson and Mollerstrom note that their story fails to answer two important issues:

There are many open questions that we have failed to address, but two stand out in our minds. First, our model takes the existence of the asset bubbles as given and does not explain their origins.

[...]

Second, our model does not explain why global interest rates fell between 2000 and 2003, and thereafter stayed at a relatively low level.

Well let me help Laibson and Mollertrom here. The actions of U.S. monetary policy can answer the first question and at least the first part of the second question for this period. As I have written before, this is easy to see given the Fed's monetary superpower status:

[T]he Fed is a global monetary hegemon. It holds the world's main reserve currency and many emerging markets are formally or informally pegged to dollar. Thus, its monetary policy is exported across the globe. This means that the other two monetary powers, the ECB and Japan, are mindful of U.S. monetary policy lest their currencies becomes too expensive relative to the dollar and all the other currencies pegged to the dollar. As as result, the Fed's monetary policy gets exported to some degree to Japan and the Euro area as well. From this perspective it is easy to understand how the Fed could have created a global liquidity glut in the early-to-mid 2000s since its policy rate was negative in real terms and below the growth rate of productivity (i.e. the fed funds rate was below the natural rate).

Given the Fed's role as a monetary hegemon the inevitability theme [i.e. the Fed had no choice but to accommodate the excess savings coming from Asia] underlying the saving glut view begins to look absurd. Moreover, the Fed's superpower status raises an interesting question: what would have happened to global liquidity had the Fed run a tighter monetary policy in the early-to-mid 2000s? There would have been less need for the dollar bloc countries to buy up dollars and, in turn, fewer dollar-denominated assets. As a result, less savings would have flowed from the dollar block countries to the United States. In short, some of the saving glut would have disappeared.

In short, the Fed set global monetary conditions at the time and pushed global short-term rates below their neutral level which, in turn, started the asset booms. Of course, financial innovations and credit abuses also played a role and may explain the persistence of the low global interest rates. I think my monetary superpower hypothesis fits nicely with the Laibson and Mollertrom story. One more nail in the saving glut coffin.

P.S. In case you are wondering, here is evidence the Fed kept the federal funds rate below the neutral rate during the early-to-mid 2000s (source). Here is more formal evidence from the ECB.