出自Investopedia 2015年11月13日
“羊群效应”在投资字典里指投资者盲目跟从已经建立的投资趋势或者模式。这些交易员是投资公理“趋势是你的朋友”的典型信徒。因为一些原因这一原则在外汇交易会比在股票交易中提供更好的回报。
首先，外汇交易受技术分析的影响比股票交易大，而基本面分析在股票中影响要比外汇大。其次，虽然外汇市场是全球最具流动性的金融市场，在2000年日交易量达到4万亿美元，但是其中6个货币（美元/欧元、美元/日元、美元/英镑、美元/澳元、美元/瑞郎 和 美元/加元）的交易量却占总量的三分之二。
这些货币时刻被世界各地的外汇交易员密切关注，同时有大量的监控设备日夜不停的监视以寻找买进和卖出的机会。一旦出现关键技术信号，交易员立刻加入并增强原来趋势，从而加剧羊群效应。
在外汇交易中运用羊群效应
在外汇交易中使用羊群效应的指导原则非常简单，那就是根据大多数人的观点和已经建立的全球市场趋势进行交易。如果你足够精明，在股票市场进行反向交易可能使你收益颇丰，但是这在外汇市场将是个灾难的开始，外汇可以无视基本面的时间超出你的想象。
2013年的日元下跌是羊群效应的很好案例。在4月，日本央行宣布将买进政府债券并在2014年加倍货币基数。日本央行企图以这个前所未有的货币政策刺激经济增长和打破日本长达20年的通缩怪圈。
交易员在2013年因为日本人口老龄化和巨额政府债务开始做空日元，由于交易员相信日本央行将继续实行宽松货币政策，日元下跌加剧。在2013年5月的第一个周，日元成为当时下跌幅度最大的货币，相对美元下跌12.4%。随着交易员蜂拥涌向做空日元，羊群效应增加了日元下跌的势头。
在2013年底，做空日元/美元实际上取代了做空欧元/美元，趋势交易员的注意力从欧元反弹到1.20后集中到了日元上。该转变可以在到2013年5月7日的一年中与美元对比看出来，欧元上升了0.32%，而日元下跌了19.3%。
羊群效应也在2013年美元对大多数货币变强中表现出来，美元在那时对16个主要货币中的13个增值。那时的美元变强很大程度上归功与美国经济回暖，使道琼斯工业平均指数和标准普尔500指数达到历史最高点，进一步吸引资本流入进入一个良性循环。
普通羊群效应外汇交易
过去几年的货币行为表明以下交易是主要的普通羊群效应。这只是建议，如果你想交易这些货币，强烈建议您做好自己的调查。
中国是许多大宗商品的最大进口国，当中国经济强劲，大宗商品出口国的货币将会受益，例如加元和澳元。在本世纪前10年中，由于中国经济的飞速增长对大宗商品的需求大幅增加，澳元和加元相对美元增值了37%。因此，在中国经济形势良好时可以考虑做多加元/美元和澳元/美元。
加元和澳元在全球经济增长强劲和对风险偏好的需求强烈时表现良好。相反，当出现担忧全球经济放缓和风险偏好缩减，这些大宗商品货币下跌并且例如美元和瑞郎这样的避险货币开始上升。在这时，主流的羊群效应是做空加元或者澳元，做多美元或者瑞郎。
虽然日元在2013年春天日元损失了大量价值，但是因为其“套利交易”的流行使其交易与全球风险偏好相反。当风险偏好消失和惊慌的投资者蜂拥交易时可能是个灾难，因为对风险资产的减价出售和因偿还贷款而对日元巨大需求引起的汇率上升将成为双重巨大打击。在2007年对日元的套利交易超过1万亿美元，但是2008年全球经济崩溃，日元对美元上升了20%。
羊群效应技巧
无经验的外汇交易员应该注意这些羊群效应技巧：
警惕一个陈腐或长期存在的趋势，因为它随时会发生反转的风险。货币趋势可以逆转非常强烈，错误的方向可能引起灾难性损失。就像一些人说的，除非你是乔治索罗斯，否则不要进行货币反向交易。
当在一个趋势中交易时，提前制定推出策略。从众可以提供安全性，只要你在大家退出时不被落下。
止损至关重要，因为高杠杆的外汇交易在交易策略没有严格执行时会引发大量经济损失。
不要忘了你在做多一种货币时正在做空另一种。做空更容易关注，这种方法可以避免自满而使盈利变成亏损。
不建议对亏损仓位进行补仓，降低平均持有价格在外汇交易中是个不怎么可行的策略。
总结
羊群效应可以帮助你在已经建立的趋势中获利，但是要使用止损、避免自满和制定退出策略。无数的交易以巨大的代价证明，趋势是你的朋友，但是它会有终止的时候。
Herd Instinct Often A Good Guide For Forex
By Investopedia Staff | Updated November 13, 2015
"Herd instinct" in the investing lexicon refers to the tendency of traders to blindly follow an established investment trend or pattern. Such traders are typically adherents of the well-known investment axiom "the trend is your friend." This principle is likely to provide better returns in forex trading than in equities trading for a couple of reasons.
Firstly, forex trading is arguably driven by technical analysis to a greater extent than stock trading, given that fundamental analysis plays a much bigger part in the latter than it does in the former. Secondly, while the forex market is the world's most liquid financial market with estimated daily turnover exceeding $4 trillion in 2010, just six currency pairs – USD/euro, USD/yen, USD/sterling, USD/Australian dollar, USD/Swiss franc and USD/Canadian dollar – accounted for two thirds of this trading volume. (Conversely, blue-chip stocks on the major global equity exchanges collectively number in the thousands).
These currencies are avidly watched by legions of currency traders around the world, and the same technical levels are monitored around-the-clock by these traders for buy and sell signals. Once a key technical gives way, other traders jump in and reinforce the initial trend, thus exacerbating the herd effect.
Using Herd Instinct in Forex
The guiding principle for using the herd instinct profitably in the forex market is a simple one – base your trades on the majority view and established trends in global markets. Being a contrarian may enable you to reap rewards in the stock market – assuming that you are astute enough to time the markets effectively – but it can be a recipe for disaster in the forex market, where a currency can defy fundamentals for so long and drift so far that it can test the resolve of the biggest and best traders.
The decline of the Japanese yen in 2013 is a prime example of the herd instinct at work. In April 2013, the Bank of Japan (BOJ) announced that it would buy government bonds and double the country's monetary base by 2014. The BOJ embarked on this unprecedented degree of monetary stimulus to foster growth and break the deflationary spiral that had plagued the Japanese economy for two decades. As a result, the short JPY/long USD trade was one of the most popular forex trades in the first half of 2013.
While traders were already shorting the yen going into 2013 on account of Japan's aging population and massive government debt, the yen's descent picked up steam as traders and speculators grew increasingly confident that the Bank of Japan would continue to ease monetary policy. By the first week of May 2013, the yen was the biggest decliner of the major currencies for the year, with a 12.4% fall versus the U.S. dollar. With forex traders rushing to put on short JPY positions, the currency looked set to break the 100 barrier, at which point the herd instinct would have added to its downward momentum.
The short JPY/long USD trade had in fact superseded the short EUR/long USD trade by 2013 as the "go to" trade for trend followers, as the attention of currency bears shifted to the Japanese currency following the euro's rebound since mid-2012 from a low of around 1.20. This sentiment shift could be gauged by the performance of the two currencies versus the greenback in the one-year period ending May 7, 2013; while the euro had gained 0.2%, the yen was down 19.3%.
The herd instinct was also evident in the strength of the U.S. dollar against most major currencies by May 2013, with the greenback on the ascent against 13 of the 16 most widely-traded currencies. The unexpected strength of the U.S. dollar at that time was largely attributed to the rebounding U.S. economy, which had driven the Dow Jones Industrial Average and S&P 500 indexes to record highs, attracting further capital inflows in a virtuous circle.
Common Herd Instinct Forex Trades
Currency action over the years indicates that the following trades are the most common "herd instinct" ones. These are only suggestions, and if you intend to trade these currencies, it is strongly recommended that you conduct your own research and due diligence.
As China is the world's biggest importer of numerous commodities, when the Chinese economy is growing strongly, currencies of commodity exporters such as Canada and Australia benefit. In the first decade of this millennium, as commodity demand soared due to the Chinese boom, the AUD and CAD surged 37% against the U.S. dollar. Therefore, consider going long CAD and AUD versus the greenback when the Chinese economy is expanding rapidly.
The AUD and CAD tend to do well when the global economy is growing strongly and demand for risk appetite is strong. Conversely, when fears abound about slow global growth and risk appetite shrinks, these commodity currencies decline and safe-haven currencies such as USD and Swiss franc (CHF) rise. At such times, popular herd instinct trades are short CAD or AUD and long USD or CHF.
While the Japanese yen had lost substantial ground by spring of 2013, it has tended to trade in a direction opposite to that of global risk appetite because of its popularity as a funding currency for "carry trades*." The carry trade strategy can be disastrous when risk appetite vanishes and panicked speculators rush to close their positions, because of the double whammy arising from the fire-sale of risky assets and the spike in the yen exchange rate due to demand for the currency to repay carry loans. More than $1 trillion had been invested in the yen carry trade by 2007, but as the global economy unraveled in 2008, the currency rose 20% versus the greenback that year.
Herd Instinct Tips
Inexperienced forex traders should note these "herd instinct" tips:
Beware of a stale trend or a long-lived one, since it may be in danger of imminent reversal. Currency trends can reverse quite sharply, and being on the wrong end of a trend reversal can lead to catastrophic losses. By the same token, unless you're George Soros, don't be a currency contrarian.
While playing a trend, plot your exit strategy in advance. Staying in a herd can provide safety in numbers, as long as you don't get crushed when the herd stampedes for the exits.
Stop losses are very critical, since the inordinately high degree of leverage in retail forex can lead to financial ruin if strict trading discipline is not implemented.
Don't forget that being long one currency means you are short the other. Short positions seem to warrant closer monitoring by traders, and this approach may help avoid the complacency that can turn a profitable position into a losing one.
Adding to a losing position is not advisable, since "averaging down" is seldom a viable trading strategy in forex.
The Bottom Line
The herd instinct can help you profitably trade established trends in forex; but use caution and commonsense within the herd – use stop losses, avoid complacency and plan your exit strategy. As innumerable traders have discovered to their cost, the trend is your friend, but only until it comes to an end.
本文翻译由兄弟财经提供
文章来源：http://www.investopedia.com/articles/forex/050913/trade-forex-herd-instinct.asp