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Epsilon Theory’s Latest: The Three-Body Portfolio

The latest from Rusty Guinn is out and it's republished over at Heisenberg Report with permission.

If you don't read Rusty's stuff, you definitely should. There aren't a lot of people out there commenting on markets that are better than Heisenberg, but Rusty is as good as me and maybe even a bit better (he's also more modest, which is a plus). 

Here are a couple of excerpts to pique your interest. Full piece at the link below:

Some regard changing perceptions, sentiment and shifting narratives as a source of short-term volatility in securities prices, and little more. Indeed, that is the implication of the old Benjamin Graham trope I disputed in The Myth of Market In-Itself — that the market is a short-run voting machine, but a long-run weighing machine. Sure, sentiment may matter in the short run, but eventually truth will out! I did a fair job, I think, of identifying my issues with that point of view, but as per usual, it was Ben that really got to the heart of the issue. In his latest note, he characterizes the occasional sharp rise in unpredictability of market outcomes — not to be mistaken for volatility — as the result of a Three-Body Problem. You do yourself a disservice if you haven’t read the piece, and probably a greater disservice if you haven’t read the Liu Cixin book of the same title recommended in it. But in short, a three-body problem refers to a system that is solvable not through elegant algorithm, but only through brute-force computation. There is no closed-form solution to predict the future locations of a set of three planetary bodies in a vacuum like, say, the Earth, the sun and the moon.

In most environments, where the purpose of markets is to efficiently and accurately price risk of various uses of capital, those markets tend to behave more or less like two-body systems. The interaction of Planet A (which we’ll call ‘fundamental data’) and Planet B (which we’ll call ‘prices’) is generally predictable. Oh sure, there’s volatility. Remember, not everyone agrees on the starting point and velocity of Planet A — at least, not since Reg FD, anyway. Information takes time to propagate. But we also know that Planet C (let’s call it ‘epsilon’) is sitting out there somewhere. Yet it’s far enough away that its gravity can’t do more than induce short- and medium term distortions in the relationship between A and B. If you knew the truth about the starting positions and velocities of Planet A and Planet B, however, you could develop a formula that would tell you within a pretty fair margin where prices would be down the line.

https://heisenbergreport.com/2017/12/27/epsilon-theorys-latest-the-three-body-portfolio/