Distributed Economics

In the textbook model of Fractional Reserve Banking then, what happens when a loan defaults?

Assume an economy with 3 banks, all of which have maximized their lending, in a 10% fractional reserve regime. In this financial system the total money supply is 3000, the total loan supply is 2700, and the reserves total 300. Bank Bravo’s loan of 100 goes into default, and is completely unrecoverable.

Thinking in detail just about how this should be handled by bank accounting,  suggests possible problems with the simple textbook description in Mankiw, et al. First, how does a Bank distinguish between the lack of loans due to default, and the absence of loans because it hasn’t made any? What stops Bank Bravo in other words, from issuing new loans in this situation, because its new deposit/loan ratio allows it to?

I have a faint suspicion, but unfortunately no access to the necessary library resources to prove this,  that there have been times and places where nothing did. Fractional Reserve Banking is something of an emergent system – it’s the result of custom and practice over several centuries, and there has been a lot of tinkering during that time to fix perceived problems with it. This also makes comparisons between different time periods very tricky – the rules have changed, and its the implementation rules that are quite critical.

It’s also worth noting that the symptoms of different problems under different fractional reserve regimes may well be very similar. There are typically many different ways to destabilize a distributed system of this kind.

Originally, banks or their equivalents issued their own bank notes, or deposit slips, in exchange for gold deposits. If a bank under this regime allowed itself to issue more loans when existing ones defaulted, then it would find that its ratio of loans to deposits/bank notes (leverage) would be steadily increasing. Since each bank then issued separate bank notes (the last remnants of this were the Scottish Banks in Great Britain until this crisis in fact), more and more of that particular bank’s notes would circulate, and presumably would either start to have their face value marked down in trade as people realised this, or just trigger a bank run.

In the modern age, something called the Capital Reserve is supposed to prevent this. When a bank is founded in the USA, it’s founders are required to provide a minimum $5 million dollar capital reserve. This is completely separate to the reserve shown above, which is a portion of the deposits. It is the combination of capital reserve and deposits that appear to control lending, which may also be why the Central Banks have considerably eased  the amount of customer deposits that must be held in reserve.  So the actual picture looks like this:

The loan loss knocks out Bank Bravo’s capital reserve, and leaves it needing to be recapitalized.  Assuming for a moment, no external inputs, &  that the Capital Reserve must be held in monetary units,  what does that do to the rest of the system?

Bank Bravo has to recapitalize by getting money to put into its capital reserve. Lets assume it does this by attracting investments from a depositor at Bank Alpha.

Bank Alpha is now not in conformance on its loan/deposit ratio, and either needs to attract more deposits, or reduce its lending. It can attract a deposit from Bravo to balance up, since Bravo now has a lower loan amount outstanding and has recapitalized. Or, it could not roll over one of its short term loans, and reduce its lending. In the former case, the total money supply is reduced, in the latter case, both the money and loan supplies are reduced. To wit (assuming that the loan was repaid with money on deposit at Bravo):

So what does this all mean?

Well, at the very least, it seems to indicate that one of the more popular American undergraduate Economics textbooks is a tad incomplete, since the system it describes could not in fact be implemented as described. Or to put it another way, if it were implemented as textbook, then as loans defaulted, which statistically speaking some number of loans will do, money and loan capacity would be progressively removed from the system, as the initial deposit expansion caused by the fractional reserve deposit/loan process went into reverse. It would reverse back to the point where the loans at the last remaining bank were in a 90% ratio to the initial deposit, then the next loan default destroys the banking system, until somebody decides to start a new one, kicking off the entire process again.

This also highlights that the theoretical model does not provide a constant money or loan supply. In fact both vary over time as a function of loan defaults.

In other words, the Fractional reserve banking system does not appear to be robust to loan defaults. This was essentially the issue Fisher raised in 1933, in his Debt Deflation Theory of Great Depressions paper. Since this is a system level problem, requiring banks to maintain deposit insurance doesn’t resolve the fundamental issue, which is that although banks are allowed to create money when they make loans, there is no good way for them to destroy that money if the loan that triggered the creation,  defaults.

Finally what the last table also indicates is that the system has multiple states. In other words, there is no single total value for the money and loan supply that the fractional reserve banking process ends up producing. It can naturally vary without any intervention in the system at all.

Anybody reading this, please comment if you think there’s anything at all wrong with the argument above.  With the preceding essays as some sort of basis for understanding the theoretical basis of the system, the next essay will take a look at the empirical evidence on how the system is implemented, before we take a look at where the central banks appear in all this.

©cc

cc Fractional Reserve System, Lending, Prologue