市场抛盘是怎样发生的？

    这种理论就是基于消费的资产定价模型。大多数关于股市运作的理论都是基于这样一种观点：投资者会思考得出亚马逊(Amazon)或苹果(Apple)值多少钱。总体上，通过买卖股票，市场先生会有一些结论。

    但基于消费的资产定价模型认为，这种方式不管用。事实上，投资者很少会花时间来考虑一家公司的股票是低估、还是高估。大多数投资者的投资决策是基于他们有多少钱，打算什么时候把它们花出去。

    “如果我现在没有现金流，但未来会有很多，我会在一段时间内很紧张，担心突然之间我会需要现金，”投资咨询公司Research Affiliates投资与研究管理团队主管克里斯•布莱特曼表示。

    纽约大学(New York University)的经济学教授西德尼•路德维金森一直支持基于消费的理论，1月初他参与撰写的一份研究报告发现，75%的短期股价变动与投资者的风险偏好变动有关。

    这种理论在解释近期的科技股抛售时非常管用。第一季度，企业利润并不比上年同期差多少。但经济的确放缓了。而且，这可能让投资个体有点担心他们拥有多少现金，以及他们是否会早于预期就需要现金。如果你担心近期可能需要现金，你不太可能投资像特斯拉、Twitter这样的公司，虽然潜力巨大，但尚未产生利润或规模利润。但你可能不会担心投资伯克希尔-哈撒韦(Berkshire Hathaway)、通用电气(GE)或沃尔玛(Walmart)这类蓝筹股。

    到4月初，美国经济开始再度提速。与此同时，科技股反弹。

    诺贝尔奖得主普雷斯科特多少认同这种观点。他认为，股价的主要驱动因素是税收政策。如果投资者们认为他们将需要支付更多税款，他们会减少投资。这不能解释今年或2008年的科技股下跌，但关键是，造成股市恐慌的不只是对股票本身的担忧。

    对于人们为什么突然之间从华尔街夺路而逃，这似乎是一个很好的答案，至少目前是这样。（财富中文网）

    译者：早稻米

    The theory is called the consumption-based asset pricing model. Most theories of how the stock market works are based on the idea that investors sit around thinking about what Amazon or Apple might be worth. Together, by buying and selling stock, Mr. Market comes to some conclusion.

    But the consumption-based asset pricing model says that’s not the way it works at all. Investors, actually, spend very little time thinking about whether a company’s shares are undervalued or overvalued. Instead, most investors make their investment decisions based on how much money they have and when they will spend it.

    “Something that has no cash flows now but a lot in the future, I would be nervous about in a period when all of a sudden I think I am going to need cash,” says Chris Brightman, who leads the research and investment management team at investment advisor Research Affiliates.

    In early January, Sydney Ludvigson, an economics professor at New York University who has been a defender of the consumption-based theories, co-authored a study that found that 75% of short-term stock price movements have to do with changes in investors appetite for risk.

    It turns out the theory does a pretty good job of explaining the recent tech selloff. In the first quarter, corporate profits weren’t any worse than they were last year. But the economy did slow. And that may have made individuals slightly more concerned about how much cash they had, and whether they would need it sooner than they thought. And if you are worried about needing cash soon, you are probably less likely to invest in companies like Tesla and Twitter, which have a lot of potential, but are not yet producing profit, or a lot of it anyway. But you might still not be concerned about investing in Berkshire Hathaway or GE or Walmart .

    By early April, the economy was starting to pick up again. And when it did technology stocks rebounded.

    Nobel Prize-winner Prescott kind of agrees. He thinks the main thing that drives stock prices is tax policy. If investors think they are going to have to pay more in taxes, they will invest less. That doesn’t really explain why tech stocks dropped this year, or in 2008—but the point is, stock market panics are not only driven by a fear of stocks.

    And that seems like a pretty good answer as to why people all of a sudden go running for Wall Street’s exits, at least for now.