fatrat wrote:
"You have some fundamental misunderstanding of what it is mathematics are doing in the world of trading.
Trading and market outcomes are random variables. All individuals are doing is modeling randomless and assessing likelihood of a certain outcome."
I think YOU have some fundamental misunderstanding of the markets. The markets are not random. Just because it's unpredictable (for the long term) does not mean it's random.
For the markets' movement to be random, it has to conform to the Normal / Gaussian distribution. It does not. There are too many outliers for it to conform to the Normal Distribution. If it can't conform to the Normal Distribution, it can't be random.
Mathematically, if the markets' distribution is normal, the kurtosis and skewness must be zero (they are not). The Hurst Coefficient must be 0.50 (it is not). The market collapse of 1987, Jan of 1994 and 1998 should not have happened (but they did. So, what are you going to believe: the reality of the markets or the delusions of the efficient market theory?).
EMT was created by Eugene Fama in 1960, based on a paper written by Louis Bachelier in 1900. Since they did not have any computers at that time for number crunching, it was easier for them to assume that the price action was random, aka Brownian Motion. If it's random, with the Normal Distribution, the math they can use becomes easier. You can use the mean, mode, median, standard deviations, z scores and such. Without the Normal Distribution, the mathematics becomes harder (there's no mean, mode, standard deviations, etc. and you'd have to cpmpute the 3rd and 4th moment about the mean - except here the mean is just a location parameter M with scale parameter C).
EMT, and its derivatives (CAPM, VaR, Portfolio Theory, etc.) that are taught in business school is basically worthless. Even Fama recently conceded as much.
The best distribution that the markets conforms to is the Stable Pareto Levy Distribution (SPL). One of the implication of the SPL is that the short term is "predictable", the long term is not. This is why you never have any accurate long term weather forecasts. Both weather systems and the markets are non linear dynamical systems, where the short term is "predictable" (if you keep it rough enough) but the long term is not (remember the "New Economy" of 2000? Dow 36,000?).
You can argue all you want about how the markets are random, except the mathematics prove that they are not.