Best of TTU – How to Test a Model Over Decades of Data

I often see the press write that too much money is chasing the same trends, and this being the reason that Trend Following strategies have been performing a little under par in the last few years.  So who better to ask if this really is true, than my friend Kathryn Kaminski, who of course co-wrote the bible on Trend Following with Alex Greyserman… as well as a book with me, that you can find on my website.  We also discussed how they conducted their research for their book, where they went back a very long time to test if Trend Following models really do work over centuries of data… so I think you will find this part of particular interest.  I hope you enjoy these unique takeaways from my conversation with Kathryn and if you would like to listen to the full conversation, just go to Top Traders Unplugged Episode 41 & Episode 42.
Return of the Trend: 'It's all about Correlation'
Niels:  I had a question the other day from someone here based in Switzerland, Roman, in fact, and he asked about people's perception about Trend Following that perhaps it's performed poorly in the last couple of years because there's been too much money chasing Trend Following after the great year of 2008. When you hear something like that, what comes to mind?
Katy:  Well, I actually just wrote an article which is coming out for Eurex on this exact topic, and I call it Return of the Trend: It's All About Correlation. I'll just give you a view on this. If you look at a Trend Following system, any portfolio system in general, we depend on correlation. We depend on the diversification across markets, and regardless of looking at the capacity in the industry, not even thinking about that, if you take a graph of correlations pre in the last twenty years, it almost looks like a step function. So up until 2008 the correlations are pretty low across all futures markets, and they just shot through the roof in 2008 and they stayed there until earlier this year, or until late 2013. If you think about portfolio construction, the returns of Trend Following is driven by divergence and we've had some divergence over this period of time: quantitative easing, all sorts of events like the nuclear meltdown in Japan, those are diversion events, but in this sharp ratio is also the diversification and the risk. When you construct a portfolio, it's not only the volatility, which has been low, but also the correlation across assets that allows you to have proper diversification. Correlation being high means diversification is low, which means that even though there maybe some trends, there's a lot of risk because it's sort of like a one trade world. If you look at that, that coincides with a period that has been difficult for Trend Following strategies. So they do have profits in some areas, but there was just not enough diversification across their portfolio I think to support their performance as consistent with history.

Niels:  Sure, sure. The next area I want to talk about is what usually is the trading program, but today, in our conversation it will be about the trading strategy or the model, however  you phrase it, that you've used in your study that really represents the performance over this long period. Tell me about how you and Alex constructed this and feel free to go into as much detail as you want.
Katy:  OK, yeah, this is a very important and good question, Niels. One of the chapters of our book that I'm most excited about is actually chapter 3, and this is one called Systematic Trend Following Basics. I found that when I looked at most other books on trend following, and those sort of descriptions, it's very hard to find a specific formula that you could use as "this is the formula" for Trend Following.  So what we did, instead, is we tried to create a framework with one formula.

'..we focus on creating one formula for Position Sizing, which is a function of several key variables."