A great reminder from technical analyst John Murphy:

“The statement ‘market action discounts everything’ forms what is probably the cornerstone of technical analysis. […] The technician believes that anything that can possibly affect the price–fundamentally, politically, psychologically, or otherwise–is actually reflected in the price of that market.”

Alfred Cowles adds:

“This evidence of structure in stock prices suggests alluring possibilities in the way of forecasting. In fact, many professional speculators, including in particular exponents of the so-called Dow Theory widely publicized by popular financial journals, have adopted systems based in the main on the principle that it is advantageous to swim with the tide.”

William Dunnigan adds:

“We think that forecasting should be thought of in the light of measuring the direction of todays trend and then turning to the Law of Inertia (momentum) for assurance that probabilities favor the continuation of that trend for an unknown period of time into the future. This is trend following, and it does not require us to don the garment of the mystic and look into the crystal balls of the future.”

Richard Donchian adds:

“When I first got into commodities, no one was interested in a diversified approach. There were cocoa men, cotton men, grain men they were worlds apart. I was almost the first one who decided to look at all commodities together. Nobody before had looked at the whole picture and had taken a diversified position with the idea of cutting losses short and going with a trend.” (more…)