Many of us have followed the dramatic rises and precipitous falls of bitcoin, and cryptocurrencies in general, over the past few years. Some may have written them off entirely after 80% declines in 2018, only to see them roar back into investors’ collective consciousness in 2020. Certainly sentiment has shifted over a short two years — more institutional investors are taking a hard look at crypto, and previous naysayers have softened their views.
This all leads to one question: How much cryptocurrency should I own?
Math to the rescue
It goes without saying that this is a hard question to answer. But we can borrow a page from modern quantitative finance to help us arrive at a potential answer. For years, Wall Street “quants” have used a mathematical framework to manage their portfolios called the Black-Litterman model. Yes, the “Black” here is the same one from the famous Black-Scholes options pricing formula, Fischer Black. And “Litterman” is Robert Litterman, a longtime Goldman Sachs quant.
Without getting into too much detail, the model starts with a neutral, “equilibrium” portfolio and provides a mathematical formula for increasing your holdings based on your view of the world. What’s amazing is that it incorporates not just your estimate about how an investment might grow, but also your confidence in that estimate, and translates those inputs into a specific portfolio allocation.
Your starting point: 0.50%
The Black-Litterman model uses the global market portfolio, meaning all the asset holdings in the world, as its starting point for building a portfolio. This means that, if you don’t have any other views on what investments might perform better or worse, this is the portfolio you should consider holding.
In early 2021, the global market for stocks totaled $95 trillion and the global bonds market reached $105 trillion. The cryptocurrency market as a whole was valued at roughly $1 trillion. This means that cryptocurrency represents 0.5% of the global market portfolio.
Just as there are plenty of arguments to hold more cryptocurrency, there are also many arguments to hold less. However, from the model’s standpoint 0.5% should be your starting allocation.
Now add your views
This is where the mathematical magic comes into play. For any given growth rate in cryptocurrency (or any investment for that matter), the Black-Litterman model will return the amount you should hold in your portfolio. What’s more, you can specify your level of conviction in that assumed growth rate and the model will adjust accordingly.
In the below chart are the portfolio allocations to bitcoin derived from the Black-Litterman model. This chart can serve as a useful guideline when thinking about how much cryptocurrency you might want to hold.
How to use it: Select how much you think bitcoin will overperform stocks, from +5% to +40%. Each return expectation corresponds to a line on the chart. For example, if you think that bitcoin will outperform stocks by 20%, this corresponds to the purple line. Now, follow the line left or right based on how confident you are. If you’re at least 75% confident (a solid “probably”), the purple lines up with a 4% allocation to bitcoin.
One of the most interesting things to note is how high your return estimate needs to be and how confident you need to be in order to take a sizable position in bitcoin. For example, for the model to tell you to hold a 10% allocation you need to be highly confident that bitcoin will outperform stocks by 40% each year.