Friday, March 16, 2018

On Nicholas Taleb, leverage and ruin

Skin in the Game by Nicholas Taleb is not finance book per se but some of its ideas are interesting enough to challenge some of my ideas of leverage. I think Taleb's ideas are worth grappling with because they can potentially change your approach towards personal finance.

One particular idea is that ensemble probability is very different from time probability. If the model reflects the ruin of a few participants out of many, it is conceptually very different from the reality where there's only one participant who has to stop permanently the moment he is ruined by the markets.

One of the better things I did last year was to open a margin account. I wanted to continue to obtain high yields from REITS but I also wanted to buy higher quality REITs with a good story and stable management. The only way to resolve this paradox is to borrow $1 for each $1 I have and invest it in the better REITs on SGX.

When I talk about my approach towards leverage, I usually begin with a back-test. The models I ultimately employ for leverage always have a yield which exceeds on average 6.5%. After accounting for the borrowing fees, I tend to get 10% yields on my invested capital.

The more interesting feature of the models I employ is that I use semivariance which I combine with the expected return to figure out what happens in a 1 in a 40 year freak market. In a typical model involving REITs, I can backtest a modest 10% return with around 13% semivariance. So there is a 2.5% chance that I will drop 2 standard deviations down on a freak year or (10 - 2 x 13)=16% lose about 1/6 of my portfolio. ( But of course, market returns are non-normal so this will happen more frequently than what my models predict. )

As a 16% drop is only about half of the margin call of 30% ( Since I  limit my leverage to 200% ), I should not have to worry so much about hitting a margin call anytime soon as the probability is less than 2.5%.

Which brings us to the problem : So long as I maintain this leverage, there will be a chance that I will bust one day. Over time, this probability is 100%. Taleb says that "in a strategy that entails ruin, benefits never offsets risks of ruin."

This is where Taleb's insight comes in useful. If I am ruined, or gets a margin call, I can't play anymore. This is what Taleb calls the uncle point. Millenials will just say GG.

The moral of the story is this. If you leverage, you will definitely be ruined over time. In your universe, there is only you ! Your ruin may even drag down members of your family if you are not careful.

But I only leverage less than 20% of net worth and can comfortably live on the dividends of my un-leveraged portfolio. Furthermore, a margin call will only wipe out 60% of my original cash outlay into my margin account.

So the moral of the story is this : Leverage only your excess portfolio. Otherwise have a plan to eventually wean yourself out of a margin account.

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