“The orders resting on BATS were typically just the 100-share minimum required for an order to be at the front of any price queue, as their only purpose was to tease information out of investors. The HFT firms posted these tiny orders on BATS—orders to buy or sell 100 shares of basically every stock traded in the U. S. market—not because they actually wanted to buy and sell the stocks but because they wanted to find out what investors wanted to buy and sell before they did it. BATS, unsurprisingly, had been created by high-frequency traders.”

Source: The Poker Face of Wall Street (2006), Chapter 1, The Art of Uncalculated Risk, p. 12

Source: The Intelligent Investor: The Classic Text on Value Investing (1949), Chapter II, The Investor and Stock-Market Fluctuations, p. 31
Context: Why could the typical investor expect any better success in trying to buy at low levels and sell at high levels than in trying to forecast what the market is going to do? Because if he does the former he acts only after the market has moved down into buying levels or up into selling levels. His role is not that of a prophet but of a businessman seizing clearly evident investment opportunities. He is not trying to be smarter than his fellow investors but simply trying to be less irrational than the mass of speculators who insist on buying after the market advances and selling after it goes down. If the market persists in behaving foolishly, all he seems to need is ordinary common sense in order to exploit its foolishness.

Source: Why Stock Markets Crash - Critical Events in Complex Systems (2003), Chapter 4, Positive Feedbacks, p. 81

Source: The Intelligent Investor: The Classic Text on Value Investing (1949), Chapter II, The Investor and Stock-Market Fluctuations, p. 43

Attributed by [Will, Hutton, http://www.guardian.co.uk/commentisfree/2008/nov/02/economics-economy-john-keynes, Will the real Keynes stand up, not this sad caricature?, Guardian, November 2, 2008, 2009-02-05]
Actual quote: "the Stock Exchange revalues many investments every day and the revaluations give a frequent opportunity to the individual (though not to the community as a whole) to revise his commitments. It is as though a farmer, having tapped his barometer after breakfast, could decide to remove his capital from the farming business between 10 and 11 in the morning and reconsider whether he should return to it later in the week."
The General Theory of Employment, Interest and Money (1935), Ch. 12 http://www.marxists.org/reference/subject/economics/keynes/general-theory/ch12.htm
Attributed

Source: The Intelligent Investor: The Classic Text on Value Investing (1949), Chapter II, The Investor and Stock-Market Fluctuations, p. 35

Source: The Intelligent Investor: The Classic Text on Value Investing (1949), Chapter II, The Investor and Stock-Market Fluctuations, p. 42

Interview in Forbes magazine (1 November 1974)
Context: Draw a circle around the businesses you understand and then eliminate those that fail to qualify on the basis of value, good management and limited exposure to hard times. … Buy into a company because you want to own it, not because you want the stock to go up. … People have been successful investors because they've stuck with successful companies. Sooner or later the market mirrors the business.