证券及金融衍生产品基本概念

Long Position and Short Position
long position 多头头寸
short position 空头头寸

在交易金融证券以及衍生产品(OTC)时，合约/产品的买入方叫做持有long position,合约/产品的卖出方叫做持有short position

拿期货这类衍生产品来说，当标的资产价格呈下降趋势时，期货多头会遭致损失。原因在于：期货合同已经把交割价固定下来了，也就是购买成本已经确定，但标的资产的价格下降了，也就意味着原有的盈利空间变小了，所以期货多头会遭致损失。

在 外汇交易 时，多头仓位是指买进一对 货币 ， 以期望在未来的一段时间内上涨。

期货类衍生产品案例
12月黄金期货价格为$980/盎司，买入即持有多头头寸，卖出即持有空头头寸。
当12月黄金期货价格下降到960/盎司时，持有的多头头寸就会造成损失，不考虑保证金和交易成本，每盎司损失20.


Investopedia关于long position的定义
http://www.investopedia.com/terms/l/long.asp
Long (or Long Position)
DEFINITION OF 'LONG (OR LONG POSITION)'
1. The buying of a security such as a stock, commodity or currency, with the expectation that the asset will rise in value.

2. In the context of options, the buying of an options contract.

Opposite of "short" (or short position).

INVESTOPEDIA EXPLAINS 'LONG (OR LONG POSITION)'
1. For example, an owner of shares in McDonald's Corp. is said to be "long McDonald's" or "has a long position in McDonald's."

2. For example, buying a call (or put) options contract from an options writer entitles you the right, not the obligation to buy (or sell) a specific commodity or asset for a specified amount at a specified date.

Long/short position in swap
Hi @artyeasel, in a plain vanilla or generic interest rate swap, an exchange of fixed and floating payments occur between 2 parties.

So there is a long-short position for interest rate swaps:
Fixed-rate payer (or floating-rate receiver) is often referred to as having bought the swap or having a long position.


Floating-rate payer (or fixed-rate receiver) is referred to as having sold the swap and being short.

An FX (currency) swap, unlike interest rate swaps, usually involves the exchange of principal and interest in one currency for the same in another currency. There is a long and short position in FX swaps too.

So if for example John was receiving USD and paying out EUR cashflows, John is long USD and short EUR.


Swap
Equity Swap
http://en.wikipedia.org/wiki/Equity_swap


Warrant
等同于中国市场的权证
http://en.wikipedia.org/wiki/Warrant_(finance)
In finance, a warrant is a security that entitles the holder to buy the underlying stock of the issuing company at a fixed exercise price until the expiry date.
Warrants and options are similar in that the two contractual financial instruments allow the holder special rights to buy securities. Both are discretionary and have expiration dates. The word warrant simply means to "endow with the right", which is only slightly different from the meaning of option.

Investopedia
DEFINITION OF 'WARRANT'
A derivative security that gives the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue as a "sweetener" to entice investors.

INVESTOPEDIA EXPLAINS 'WARRANT'
The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months.

Short Sell
卖空，融券

ADR
美国存托凭证（American Depositary Receipt，ADR