Robot Trading Will End in Disaster
Today, stock markets and other markets, such as bonds and currencies, can best be described as ‘automated automation’.
Here’s what I mean.
There are two stages in stock investing.
The first is coming up with a preferred allocation among stocks, cash, bonds, etc.
This stage also includes deciding how much to put in index products or exchange traded funds (ETFs, which are a kind of mini-index) and how much active management to use.
The second stage involves the actual buy and sell decisions — when to get out, when to get in, and when to go to the sidelines with safe-haven assets such as US Treasury notes or gold.
What investors may not realise is the extent to which both of these decisions are now left entirely to computers….
Fallacies of the market
I’m not talking about automated trade matching where I’m a buyer and you’re a seller, and a computer matches our orders and executes the trade. That kind of trading has been around since the 1990s.
I’m talking about computers making the portfolio allocation and buy/sell decisions in the first place, based on algorithms, with no human involvement at all. This is now the norm.
Eighty percent of stock trading is now automated in the form of either index funds (60%) or quantitative models (20%). This means that ‘active investing’, where you pick the allocation and the timing, is down to 20% of the market. Although even active investors receive automated execution.
In all, the amount of human ‘market making’ in the traditional sense is down to about 5% of total trading.
This trend is the result of two intellectual fallacies.
The first is the idea that ‘You can’t beat the market.’ This drives investors to index funds that match the market. The truth is you can beat the market with good models, but it’s not easy.
The second fallacy is that the future will resemble the past over a long horizon, so ‘traditional’ allocations of, say, 60% stocks, 30% bonds and 10% cash (with fewer stocks as you get older) will serve you well.
But Wall Street doesn’t tell you that a 50% or greater stock market crash — as happened in 1929, 2000 and 2008 — just before your retirement date will wipe you out.
But this is an even greater threat that’s rarely considered…
Automated investing makes a crash worse
In a bull market, this type of passive investing amplifies the upside as indexers pile into hot stocks like, for example, Google and Apple have been.
But a small sell-off can turn into a stampede as passive investors head for the exits all at once without regard to the fundamentals of a particular stock.
Index funds would stampede out of stocks.
Passive investors would look for active investors to ‘step up’ and buy.
The problem is there wouldn’t be any active investors left, or at least not enough to make a difference. There would be no active investors left to risk capital by trying to catch a falling knife.
Stocks will go straight down with no bid. The market crash will be like a runaway train with no brakes.
It comes back to complexity, and the market is an example of a complex system.
One formal property of complex systems is that the size of the worst event that can happen is an exponential function of the system scale.
This means that when a complex system’s scale is doubled, the systemic risk does not double; it may increase by a factor of 10 or more.
This kind of sudden, unexpected crash — which seems to emerge from nowhere — is entirely consistent with the predictions of complexity theory. Increasing market scale correlates with exponentially larger market collapses.
Welcome to the world of automated investing. It will end in disaster.
All the best,