Understanding financial markets with MV=PY – a look at the bond market

Recently I have been thinking whether it would be possible to understand all financial market price action through the lens of the equation of exchange – MV=PY. In post I take a look at the bond market.

The bond market – its about PY expectations

A common misunderstanding among economic commentators is to equate easy monetary conditions with low bond yields. However, Milton Friedman long ago told us that bond yields are low when monetary policy have been tight – and not when it has been loose. Any Market Monetarist will tell you that monetary conditions are getting easier when nominal GDP growth is accelerating and and getting tighter when NGDP growth is slowing. So with this Friedmanite and market monetarist insight in mind there should be a relationship between higher bond yields and higher nominal GDP growth. Hence, when market participants expect MV to increase then we should also see bond yields increase.

The graph above shows the correlation between 10-year US bond yields and US NGDP growth. The graph illustrates that there is a fairly close correlation between the two series. Higher bond yields and higher NGDP hence seem to go hand in hand and as we know MV=PY we can conclude that higher bond yields is an indication of looser monetary policy. Furthermore, we should expect to see bond yields to increase – rather than decrease – when monetary policy is eased. Or said in another way – any monetary action that does not lead to an increase in bond yields should not be considered to be monetary easing. 

Therefore, given the present slump we are in we should not be worried that rising bond yields will kill off the recovery – rather we should rejoice when long-term bond yields are rising because that is the best indictor that monetary conditions are becoming easer and that that will push up nominal GDP.

The brief discussion above in my view confirms some key market monetarist positions. First, financial markets are good indicators of the stance of monetary policy. Second, monetary policy works through expectations – with long and variable leads. Third low bond yields is an indication that monetary policy has been tight and not that it is loose.

UPDATE: In my original post I had used some wrong data. Clare Zempel kindly notified me about the mistake(s). I am grateful for the help. As a consequence of the wrong data I have revised part of the original text.

UPDATE 2: David Beckworth has an excellent post arguing the exactly the same as me: “the recent rise in long-term yields can be interpreted as the bond market pricing in a rise in the expected growth of aggregate demand.”. And take a look at David’s graph showing the relationship between expected NGDP growth and 10-year bond yields. Great stuff!

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