《外汇交易实战图表与交易心理 》 作 者：(新加坡)许强 (美国)Gary Weiss

一般来说，若未平仓合约之数量愈多，投资者相信后 市会以单一方向发展，而后市出现大幅波动的机会会愈大， 但单从观察未平仓合约之多寡并不能提供有用的数据，帮 助投资者预测大市方向，我们需要另外观察其他之数据。 当大市大幅上升时，未平仓合约亦大幅增加，而期货之溢 价亦同时上升，此时表示大市预期会出现继续上升的局面； 但假如大市大幅上升，但未平仓合约开始下跌，而期货之 溢价亦同时下跌，即表示大市预期快要见顶，所以开始平 掉部分合约，以致未平仓合约之数量下降。

在另一情况下，若大市出现大幅回落，而未平仓合约 不断增加，同时出现大幅低水的现象，表示大市之跌势极 可能会加剧，同时跌势亦会持续；但若当大市下跌时，未 平仓合约之数量开始降低，而低水情况开始好转，即表示 大市快到底，短期内可能会出现反弹局面。

Range:价格区间，指的是价格在某一范围内上下波动 的情形。

Options Are they really the better way to trade

In many ways the concept of an option is one that is almost uniformly couched with intrigue and unfamiliarity. Maybe this is due to the fact that options can be classified within a larger group commonly referred to as derivatives. Using its most basic definition, a derivative is something that has its price determined by the price of something else. Whatever the reason, this generalized construction tends to create a great deal of difficulty for people to come to terms with. However, in actual fact, this same fundamental component (i.e. being a derivative) is precisely what makes the vehicle so attractive to trade. For example, an option price will always reflect the value of its underlying source, but it will also have pricing variables that are unique to the actual option itself. These component parts can generally be derived using mathematical formulas and are often referred to using Greek letter abbreviations as follows:

Gamma The rate of gain or speed of the increase in the option price at different levels in the underlying price.

Delta The equivalent amount of traded principal that seems to be represented by the option at different price levels of the underlying.

Theta The time value left for an option to be exercised,until it effectively expires.

And, of course the most widely used, and concurrently misunderstood Vega or volatility.

With the exception of Volatility, all other measurements are capable of being derived mathematically to a fair degree of certainty, and are generally plugged into computer pricing models for options, which themselves have become reasonably common. Volatility, however, unlike these other pricing components usually reflects what can be referred to as the unknown variable. In fact, most options pricing models will leave this input field as a blank, always to be supplied by the user. However, since it is critical to understand that in order to price an option, some assumption for volatility must be used, it is also interesting to note that Volatility is in fact traded almost as an independent vehicle and usually is priced for standard term increments by banks, option market makers, and even organized exchanges themselves. Since volatility moves with the differing expectations of traders during any period of time, it is usually the singular differentiating component for any option pricing model.

Suffice it to say, the discussion of each option pricing component, much less Volatility on its own, can be the subject of many pages of mathematical description. For the purposes of this discussion however, and in fact for most traders, it is important to understand only two basic themes. Firstly, that option prices are derived from component parts which, with the exception of Volatility, are knowable. And, secondly, that anyone using an option pricing model can always derive a theoretical option price through the use of a volatility number that is available from numerous sources.

Still, the question remains as to whether by trading options as opposed to the outright underlying vehicle; there is an advantage to be gained in one*s trading approach in general. The answer, of course, is that in most cases, it is somewhat dependent upon circumstances. For example, as noted above, options have a wide range of pricing characteristics that are in addition to those of tHe underlying trade vehicle. Tliis usually represents an opportunity for evaluating many different elements of price simultaneously and making a more inclusive judgment about absolute price levels in general. In certain instances, one might argue that an option price is cheap or expensive depending on one or more of its component parts, and thereby represents either a selling or buying opportunity, independent of the actual price direction of the underlying vehicle. More importantly however, there is also an argument to be made that these same component parts of an option price, are actually related to market sentiment about the future direction for the price of the underlying in absolute terms.