All knowledge has an expiration date
If you’ve ever gotten a first aid certificate you’ll know you’ll constantly have to refresh it because new knowledge of the best way of treating injuries is constantly being updated.
Like maybe someone was taught to treat burns with cream but hopefully they’ve updated that knowledge now because it’s now known to be a poor practice.
I had one of those moments this week.
I’ve spent most of today reading, “Beyond the Status Quo: A Critical Assessment of Lifecycle Investment Advice”, and the TLDR: “the optimal portfolio is 1/3 domestic stocks and 2/3 international stocks regardless of age”.
This sounds bonkers on the face of it. It is counter intuitive to a lot of common advice of, “reduce your exposure to risk as you get older”.
I think the main reason why is the 30 year standard deviation of the return of stocks is 1.9% and for bonds it’s 2.8%. The 1 year standard deviation is 17.6% for stocks and 9.4% for bonds. At the 10 year investment horizon stocks become less volatile than bonds.
My take away is stocks have high volatility from year to year but become less volatile with more time.
The reason why I’m reading this paper
I was looking for some graphs for a blog/video series on super, I’m going to make an explainer and a walkthrough on understanding investment options, maybe make a flow chart for when to do more research in when to consider switching etc. I wanted some pretty pictures on risks/assets and to get my reference material in order.
I now have further questions about this idea too, what does this mean for the 4% rule?
I also have some initial criticisms of the paper, first off it’s US based and uses US social security for it’s retirement modeling.
The modelling of household income could do with a bit of refinement too. They assume a 2 person household of a man and a woman of equal age, they use monte carlo variance on longevity based on gender, but they assume the two earn the same amount and spend the same amount of time in the workplace. Which has statistically been shown to not be true. Women tend to earn less on average and tend to spend more time out of the workplace.
There’s plenty of awesome content in exploring this idea further, but I didn’t expect I had to fundamentally change one of the ideas I held about long term investing.
I think the psychology of money will prevent a lot of people maintaining this type of portfolio well into retirement though. I also can’t imagine financial advisor’s switching over to this idea instantly. It’ll take time and further testing of this idea to stick.
