Quoted from the book "Security Analysis" (1951, third version) by Benjamin Graham, et al. On page 653, he remarked about the Chart Reading (Market Analysis):
... Security analysis and market analysis are alike, therefore, in the fact that they deal with data that are not conclusive as to the future. The difference, as we shall point out, is that the security analyst can protect himself by a margin of safety that is denied to the market analyst. [margin of safety refers to buying way below the intrinsic business value of the stock]
.. human impatience plus the exigencies of the chart reader's profession impel him to draw more frequent conclusions from less convincing data.
... The stock speculator does suffer, in fact, from a well-nigh incurable ailment. The cure he seeks, however, is not abstinence from speculation but profits. Despite all experience , he persuades himself that these can be made and retained; he grasps greedily and uncritically at every plausible means to this end.
The plausibility of chart reading, in our opinion, derives largely from its insistence on the sound gambling maxim that losses should be cut short and profits allowed to run. ... But in this conclusion there lurks a double fallacy. Many players at roulette follow a similar system, which limits their losses at any one session and permits them at times to realize a substantial gain. But in the end they always find the aggregate of small losses exceeds the few large profits. (This must be so, since the mathematical odds against them are inexorable over a period of time). The same is true of the stock trader, who will find that the expense of trading weights the dice heavily against him.
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