Saturday, September 1, 2007

A Random Walk Down Wall Street

Just finished up the book "A Random Walk Down Wall Street". It is required reading for my finance course, first few chapters anyway. Started it while on vacation and could not really put it down. I would call this book an excellent perspective, must read before you try to game the market.

However, just to add my 2 cents.
1. The market would not be a random walk if it were not for all the schemes people attempt. Each scheme forces the market to be random. I believe the systematic risk of a any given stock is based on the risk of the leadership of such company. Strong leadership, strong business. Read "Good to Great" to understand. The measurement of risk based on numbers at best (in my opinion) can only be used to predict some for of short run direction. As this information is no better than a chartist and any scheme would just serve to further "A Random Walk".

2. I did not see "Game Theory" discussed at all in the book, though I am sure there must be something out there on the topic. My guess is that unsystematic risk driven by plain old schemes, behavioral finance theory and even arbitrage are no more than forms of game theory. The real scheme would be if everyone learned from each other and played some form of tit-for-tat game theory. However with combination of independent and institution players and the global competitiveness this would not be possible.

As it relates to risk vs return, higher risk in the market only produces more returns for those in control of the risk. If others now your risk they can play against it (sounds game theory to me).

Moral of the story?
a. Long run thinking will be productive, assuming everyone else is coming up with schemes.
(corollary - There could be a situation of long run game theory which destroys you and the market)
b. Short run schemes can pay off, but its not much better than luck and gambling. Even the greatest theory could be undermined with others playing game theory against you. And hence timing of taking your money would just be luck.