Think

역사적으로 주식으로 돈을 번 경제학자는 거의 없다.

노벨경제학상( Myron Scholes and Robert C. Merton)까지 받은 사람이 경영한 롱텀캐피털매지지먼트는 그린스펀을 경제 대통령으로 만들 만큼 크게 말아먹었다.

하지만 그 와중에도 주식 부자가 된 두 경제학자가 있었으니,

리카도와 케인즈다... 

리카도는 당시 인구론으로 유명한 맬서스와 사상적인 면에서는 서로 많은 갈등이 있었지만

맬서스의 재산을 주식으로 부풀려 줄 만큼 친한 사이었다고 한다.

아마도 어려서부터 아버지가 주식시장에서 일하는 것을 보고 자란 것이 도움이 되지 않았나 싶다.

리카도가 당시에 투자해서 돈을 번 주식회사가 지금도 있을까?

케인즈는 주식과 관련해서 유명한 말도 남겼다.

주식시장에서 어떤 주식을 사야하는냐를 결정할 때 그 기업의 주식가치보다는

다른 사람들이 오를 것이라고 생각하여 남들이 사는 주식을 사야 한다는 것...beauty contest...

Keynes was ultimately a successful investor, building up a substantial private fortune. He was nearly wiped out following the Stock Market Crash of 1929, but he soon recouped his fortune. He enjoyed collecting books: for example, he collected and protected many of Isaac Newton's papers. He was interested in literature in general and drama in particular and supported theCambridge Arts Theatre financially, which allowed the institution to become, at least for a while, a major British stage outside of London.

At age 14, after a brief schooling in Holland, Ricardo joined his father at the London Stock Exchange, where he began to learn about the workings of finance. This beginning set the stage for Ricardo's later success in the stock market and real estate.

Ricardo's work with the stock exchange made him quite wealthy, which allowed him to retire from business in 1814 at the age of 42. He then purchased and moved to Gatcombe Park, an estate inGloucestershire.

A Keynesian beauty contest is a concept developed by John Maynard Keynes and introduced in Chapter 12 of his masterwork, General Theory of Employment Interest and Money (1936), to explain price fluctuations in equity markets. Keynes described the action of rational agents in a market using an analogy based on a contest that was run by a London newspaper where entrants were asked to choose a set of six faces from 100 photographs of women that were the "most beautiful". Everyone who picked the most popular face was entered into a raffle for a prize.

A naive strategy would be to choose the six faces that, in the opinion of the entrant, are the most beautiful. A more sophisticated contest entrant, wishing to maximize his chances of winning a prize, would think about what the majority perception of beauty is, and then make a selection based on some inference from his knowledge of public perceptions. This can be carried one step further to take into account the fact that other entrants would also be making their decision based on knowledge of public perceptions. Thus the strategy can be extended to the next order, and the next, and so on, at each level attempting to predict the eventual outcome of the process based on the reasoning of other rational agents.

“It is not a case of choosing those [faces] which, to the best of one’s judgment, are really the prettiest, nor even those which average opinion genuinely thinks the prettiest. We have reached the third degree where we devote our intelligences to anticipating what average opinion expects the average opinion to be. And there are some, I believe, who practise the fourth, fifth and higher degrees.” (Keynes, General Theory of Employment Interest and Money, 1936).

Keynes believed that similar behavior was at work within the stock market. This would have people pricing shares not based on what they thought their fundamental value was, but rather based on what they think everyone else thinks their value was, or what everybody else would predict the average assessment of value was.

Other, more explicit scenarios help to convey the notion of the beauty contest as a convergence to Nash Equilibrium when the agents in the game behave perfectly rationally. The most famous such example is a contest where entrants are asked to pick a number between 0 and 100, with the winner of the contest being the person that is closest to 2/3 the average number picked for all contestants