机械化的交易系统 —— 再谈纪律的重要性

编者前言：

俗话说得好：欲加之罪，何患无辞。对于每项投资决定，我们都能找出一堆理由来支持它，也可以找出一堆理由来反对它。但问题是，你的这些“理由”是否每次都在变换？例如，今天是分析机构的股票评级让你决定买，明天是技术图形的阻力突破让你决定买，后天是某某论坛的某某高手让你决定买…… 你是否有一套放之四海而皆准的参考指标来指导每一次的投资决定？

人类是非常情绪化的动物，我们很容易受到干扰，禁不住诱惑，导致冲动进场、冲动交易。为了避免这些，我们需要总结一套信得过的交易系统，用历史数据反复验证，用Pager Trading反复磨练。这套系统可能很简单，无需复杂的概念，但关键是要持之以恒，机械化地执行每一个信号。不能因为别人说什么，或者媒体说什么而改变你的“理由”，也不能因为一两次的信号失误而彻底放弃已经验证过的交易系统。要想在股市中获利，耐心和纪律是最最重要的。成功的方法有很多种，失败的原因只有一个：不守纪律。

The Virtues of Discipline

By Mark Hulbert, MarketWatch.com, June 10, 2003

At my first speaking engagement at an investment seminar in 1981, I was scheduled to give a workshop at the same time as Richard Fabian, founder of the Telephone Switch Newsletter.

Only four investors showed up for my workshop. Fabian drew more than 1,000. Attendees were pushing and shoving to hear what Fabian had to say.

I was deeply impressed. If I recall correctly, I ended my workshop early so that the five of us could go hear Fabian.

I was amazed. Fabian was telling investors that they could duplicate his entire market timing system -- based on whether the market was above or below its 39-week moving average -- in less than a minute per week, yet his money-management fee was much higher than the industry average. In effect, Fabian was selling his discipline in actually adhering to the dictates of his system.

The line of people wanting to sign up went out the door.

I have thought a lot about Dick Fabian in recent weeks as I monitored the performance of his newsletter, now called Successful Investing and edited by his son, Douglas.

If the younger Fabian had followed the 39-week moving average with the discipline his father was extolling in 1981, the newsletter would have issued a buy signal on March 21. Fabian the son chose to ignore that signal, however, and ended up not buying into the stock market until May 30, some two and one-half months later -- when the average stock, as measured by the Wilshire 5000 index (97199001: news, chart, profile), was nearly 13 percent higher.

Why did Douglas Fabian ignore the dictates of the 39-week moving average? On his March 21 hotline, Fabian gave eight reasons:

1. The 39-week moving-average buy signal was generated on a triple witching day, and such days typically experience heightened volatility. Market strength on such days "may not reflect the underlying trend."
2. The economy is weak.
3. P/E ratios are high.
4. Key market averages are below their 52-week moving averages.
5. Investor sentiment is bullish.
6. This isn't 1991. "Investors over the past week have been covering short positions in the hopes that we'll have a repeat of 1991's wartime rally. That would be nice, but betting the farm on what happened in the past means significant downside if history fails to repeat itself."
7. "We're closing in on the top of the market's recent trading range."
8. "We're just a headline away from more declines."

These were perfectly decent reasons, of course. But by questioning his mechanical timing system, Fabian in effect started down a slippery slope, at the bottom of which is the absence of any investment discipline.

This slope is so slippery because there always are good reasons on both sides of every investment question. Regardless of where investment advisers come down on any question, they will have no difficulty finding a whole host of good arguments to justify their positions.

In fact, this ability to rationalize virtually any position is evident in the eight reasons Fabian gave in March. Note that at least five of those eight reasons remained just as valid when he issued a buy signal at the end of May as when he used them to justify ignoring his buy signal in March.

Disciplined adherence to a mechanical strategy is what keeps us from slipping down this slope. Only in that way, the elder Fabian so vehemently argued nearly 25 years ago, can we confidently say that our emotions are not running the show.

He was right.

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