收市钟声敲响之后，不论是纽约证券交易所的实体钟声还是纳斯达克的虚拟钟声，你可能单纯的以为一天的交易活动就这么停下来了，你进行股票投资购买的那些股权公司也都停下脚步，安静的等待着第二天市场的重新开盘。要知道，事情可能并不如你想的这样简单。
转眼幕后，你所投资的那些股权公司可能正参与目睹着“暗盘交易”中各种不为人知的经济活动，所谓“暗盘”，就是那些运作于普通投资者和监管机构企及范围之外的二级股市。
交易的阴阳两面
在金融术语中，“暗盘”的对立面是“明盘”。明盘交易是受监管、公开的交易行为，就像平时我们在纽交所和纳斯达克看到的那样。在明盘交易中，任何想买进或抛售股票的人都可以了解掌握他将要投资的那家公司的所有经济活动信息，包括交易量，而且每个人都可以掌握到这些资料。
暗盘交易就不是这样了，它是那些大机构投资者的私人交易空间，也叫“暗池交易”。在暗池交易中，经纪人们进行的通常是普通投资者没有办法触及的大笔的股票交易。暗池的私人运营商包括英国服务商公司Liquidnet Ltd，Pipeline，还有代理运行操作像全球最大股权交叉系统瑞士信贷和其匹配引擎，还有高盛Sigma X。
为什么要在暗池进行交易呢？这样说吧，如果一个投资机构想要在传统的公开股票市场上转移某个公司的一大笔股票，那么他可能会发现这批股票大量流向市场，并出现了价格扭曲，这样便会造成他们利益的不稳定。然而，如果在暗池进行这样的操作，机构投资者们就可以按照他们自己的想法进行大额交易，而且不至于使自己陷于劣势。
老百姓的市场
根据金融时报调查，包括美国的大型代理运行操作商，共大约有50个暗池操作。该报还估计，现在近40%的股票交易行为都是发生在传统股票市场之外的这些暗池当中，在普通投资者的视线范围之外竟然还存在规模这么庞大的交易活动。
股票市场原本就是属于普通民众的金融交易市场，它帮助中产阶级赢得谋生本职工作之外的一笔收入，也算是在全球蓬勃发展的商业活动中分得一小杯羹。荷兰东印度公司是最早期的公开股票公司之一，它就是因为允许任何阶级任何身份的人来购买股票而著名的。
但也许更重要的是，股票市场一直是美国和英国的大公司主要的赚钱工具。不同于英美两国，德国的公司更倾向于向银行融资，而日本公司通常是通过购买另一些公司的大部分的股票来促进经济增长。在美国和英国，企业大都通过让自身先发展壮大以吸引小投资者的加盟。
让投资者继续投资于经济系统
暗池是市场的产物，服务于特定的目的。当大型投资者需要四处移动大量股票的时候，暗池便提供给他们一个更加公平的竞争环境。从个人投资者的角度来看，大可以辩称，让这些公众视线范围之外的大型交易活动也很有用，因为它们能造成价格扭曲。
并且对于任何商品来说，都有批发市场和零售市场。无论是买家或是卖家，在进行大宗交易的时候，怎么样也会比那些束手无策的消费者们更有获利途径。
但有的时候，收入差距能大到一定程度，以至于那些处在在底层的人对系统失去信心，并且不再参与其中，或者更糟的是，开始联手反对它。同理，那些让人感觉竞争完全有失公平的交易大厅就可能会导致普通投资者对股票市场丧失信心。而这种民众投资者的信心，洽洽正是监管部门应该全力保护的东西。因为价值上百万的储备金和大学基金，包括所有的企业及就业岗位，都依赖于这些宝贵的民众信心。
After the closing bell rings, whether it's the physical bell of the New York Stock Exchange or the virtual bell of the Nasdaq, you may believe that trading activity has ceased for the day and the shares of the companies you trade in are sitting quietly until the markets open again the following day. That's not necessarily true.Behind the scenes, your companies may be seeing trading action in so-called "dark pools," secondary stock markets that operate out of sight of the average investor and beyond the reach of regulators.
The Yin and Yang of Trading
In financial jargon, "dark" is the opposite of "displayed." Displayed pools are regulated, public stock exchanges, examples of which include the NYSE and the Nasdaq. In a displayed pool, anyone who wants to buy or sell a particular equity has an equal view of all the activity going on with that company's available shares, including the volume being traded.Dark pools are private exchanges that are used by institutional investors. In dark pools, brokers are typically trading large numbers of companies' shares, shares the average investor has no access to. Private operators of dark pools include Liquidnet and Pipeline, as well as broker-run operations like Credit Suisse's (CS) CrossFinder and Goldman Sachs' (GS) Sigma X.Why trade in dark pools at all? If an institutional investor tried to move a large block of a company's shares on a traditional public exchange, that investor would likely find that the large volume moved the market, with a resulting price distortion. By trading in dark pools, institutional investors can trade at the enormous volumes they need to without automatically putting themselves at a disadvantage.
The People's Market
According to Financial Times, there are about 50 dark pools operating in the U.S. Counting the big broker-run operations, the newspaper estimates that nearly 40% of equity trading volume now occurs outside the traditional stock markets and in these dark pools. That's a lot of trading being done outside the view of the average investor.The stock market has its origins as a people's market, a way for middle-class citizens to get a share in the world's burgeoning commercial activity beyond what they did to earn a living. The Dutch East India Company was famous for being one of the first public companies to let anyone off the street buy a share.But maybe more important, the stock market has been the primary capital creator for companies in the U.S. as well as the U.K. While German companies were more likely to turn to the banks for funding, and Japanese companies bought large blocks of stock in one another's companies to support growth, in America and Britain, companies rose on their ability to attract a larger volume of small investors.
Keep Investors Invested in the System
Dark pools are an invention of the marketplace, and serve a purpose. For big investors that need to move enormous numbers of shares around, dark pools offer a more level playing field. From the individual investor's perspective, one could argue that keeping these big trades off the public exchanges is also useful because of the price distortions they can inflict.And for any commodity, there have always been wholesale and retail markets. Buyers and sellers who can deal in large quantities have always had pricing advantages over the average end-of-the-line consumer.But just as an income gap can get so wide that those at the bottom lose faith in the system and stop participating in it, or worse, start to work against it, the perception of an overly tilted playing field on the trading floor can cause the average investor to lose faith in the equities market. And that trust is something regulators should look to preserve. Millions of nest eggs and college funds depend on it, as well as all the companies and jobs that nest-building creates.
