Low Interest Rates, Excess Saving, and Bubbles

It seems like the belief that low interest rates cause bubbles is all the rage. Its superficially such an obvious relation “low rates” means “easy money” which means people “bid up” assets and hey presto instant bubble.

Unfortunately, its all wrong. What really causes bubbles is too much saving. For a given level of technical progress, an economy has an optimal capital stock. We define the the optimal capital stock through its equilibrium condition: there is no productive investment (which can be made by the private sector) which has a risk adjusted return which is better than zero.

Now of course, in the real world there is always new innovation, and replacing deprecated capital, so we would really expect the optimal (real) rate to be slightly above zero. Nevertheless, zero real return on capital is where an economy wants to be, where it strives to be. However, the optimal stock is not fixed, it is in fact rapidly changing. New technology can create new possibilities for investment, or it can render old capital irrelevant. The new tech industries are much less intensive than the old “heavy” industries that they are largely replacing. Nevertheless, this capital stock represents the maximum stock of savings  that can be carried into the future. If people want to save more than this, they have no choice but to invest in assets with a negative real rate of return.

Real capital investments are funded by foregoing consumption in the present in order to get more later. This is what the interest rate asks, it says, how much extra consumption do you need in the future to persuade you to forgo consumption now, so that we can build this useful investment. The more people want to save compared tot he optimal stock of assets, the more negative the real rate of return must become. The more the real rate or return becomes negative  the more “bubbles” people will see.

There is really only one possible strategy for this, and it amounts to aligning the stock of capital investments with peoples desire to save. This is possible because:

(1) Often capital investments are inhibited by real world factors like unstable government, poor human capital, poor infrastructure. Stabilising Africa and parts of the IndoChina region would offer plenty of investment opportunities.

(2) Government funded spending. There are plenty of productive investments that only a government can make, and through either higher taxes (on those who over-save – the rich) or higher deficits (providing more safe assets). These include: Education – the state of UK and US public education is a joke, and severely inhibits future productivity; Infrastructure – some projects are simply too large for the private sector to undertake; Regulation – the UK house market is a typical example, where poor government regulation prevents housing stock being built at the required pace; Free trade – this is a little less obvious, but take for example, US energy protectionism (preventing the export of shale gas), this prevents the optimal level of investment in shale technology, by keeping the price artificially low. On the other hand, it raises the risk premium for investing in oil and gas outside the US (as it could be made unprofitable through an arbitrary regulatory announcement), which reduces investment outside the US aswell. Essentially, people aren’t stupid – they will not invest in a product which depends purely on regulatory trade barriers unless they are convinced that they are here to say.

(3) Transfer payments. By transferring income from those with a high propensity to save (rich people/middle class) to poorer people, you lower the overall savings rate.However, this is not likely to be too effective in a UK/US centric view, as most of the excess savings appear to be coming from Japan, Germany and China as a response to their coming demographic disasters. UK particularly does not suffer from excess savings 🙂

Any time the total quantity of saving is in excess of the total stock of capital, a bubble is guaranteed, by draining savings out the system through government investment, we get higher total productivity, higher interest rates for savers, and fewer bubbles. Win Win Win?

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About worldofinterest

I know I live in my own world, but I like it: they know me here.

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