I Have Now Read a Paper on Momentum

日期:2014/05/13

I have now read te paper sent me by a momentum fan. Our friend, Mr. Zachar, has a poignant phrase to describe such papers: "your own man". The paper consists of a series of hypothetical critiques of momentum, which he then debunks. somehow he concludes that value beats growth. But all the prospective studies in the last 5 years, show that growth beats value.

The problem with the studies from my viewpoint is that they don't take account of ever changing cycles. The results from the 19th century don't really affect the current, since the strategy was not followed. The problem with studies of value from the past is that they use retrospective studies in one form or another. And the results are highly dependent on trying to find the few 10 bagger stocks that didn't go bankrupt that are still in the files and remain in the lowest decile of price to book.



The other problem from my viewpoint is that they don't take account of the Gordon model. The return on stocks comes from making a high return on capital say 15% and the compounding effect. Momentum and value go against this in one way or another. There are several fund that try to track trend following funds in real life. There's an ARQ managed futures fund that tries to replicate the performance of momentum funds. It's down 7% this year. The fund was started in 2010 and it's down from there. But it still has 6.3 billion in it.

I believe Dimson tried to track the performance of the best versus worst stocks in a year, and found that in 2008 the best performed 80 percentage points worse than the best. Such results would give one pause. I previously reviewed a study from France where the regression results of trend following showed no practical significance, i.e. a strung out beta of 0.03. I would have to study the Fama french data much more closely, to see how much retrospection is involved. But since the results don't hold up in the real world, I will not review the errors in such, too closely. All this is from memory, and I will have to check all the references to get the figures and references correct.