Treatment of the apparently whimsical fluctuations of the stock quotations as truly non stationary processes requires a model of such complexity that its practical value is likely to be limited. An additional complication, not encompassed by most stock market models, arises from the manifestation of the market as a nonzero sum game.

Chapter Nine, Weighted Statistical Logic And Statistical Games, p. 295 - The Theory of Gambling and Statistical Logic (Revised Edition) 1977