February 05, 2015
There has been concern expressed in some circles about the growing ratio of debt to GDP in countries around the world. Neil Irwin has a piece on this issue in today’s Upshot section of the NYT.
Such concerns are seriously misplaced for a simple reason: the market value of debt is inversely related to the interest rate. The point here is a simple one. Imagine an infinitely lived bond that pays $50 a year in interest. If the prevailing interest in the market for long-term debt is 5 percent, the price of this this bond will be $1,000. However if the interest rate were to rise to 10 percent, the price of the bond would be just $500.
At present, interest rates worldwide are very low by historical standards. This has created a situation in which the market value of debt is very high. However if interest rates were to rise, then the market value of this debt would plummet.
Consider the case of Japan, which can now issue 10-year bonds paying just 0.3 percent interest. If the interest rate on 10-year debt rose to 3.0 percent (still a very low level) the market value of this debt would fall by close to one-third (the exact decline would depend on the timing of the increase). The decline in the market value of longer term debt would be even greater.
The same story applies to private debt. if interest rates were to rise and companies were troubled by the amount of debt they had outstanding they could just issue new bonds and buy up the existing debt at large discounts, thereby reducing their debt burden.
If we want to take a serious look at the extent to which debt is imposing a constraint on economies around the world we should look at the ratio of interest to GDP. That doesn’t look very frightening in the U.S. and I suspect there is a similar story in most other countries around the world.
Addendum:
I should also point out that high debt burdens are actually in part a direct outcome of low interest rates. Low interest rates mean it’s cheap to borrow, therefore governments, businesses, and households will borrow more. That is actually what we should want to see in a downturn, it means more demand in the economy.
Ideally, governments would take advantage of low interest rates to invest in infrastructure, research and development, and education. Businesses are taking advantage of low interest rates in part to invest and in part to buy other companies. It’s cheap, why shouldn’t they borrow to buy up shares? Households aren’t borrowing against home equity like they did in the bubble years, but undoubtedly many are taking advantage of low interest rates to pay their kids’ education or other spending.
Anyhow, we can look to arithmetic and logic to see the impact and cause of higher debt to GDP ratios. Alternatively, we can ignore arithmetic and logic and yell about the debt and the sky falling. It’s your choice.
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