愛華網(wǎng)Some form of risk taking is inherent to any business activity. Somerisks are considered to be "natural" to specific businesses, suchas the risk of oil prices increasing or decreasing is natural tooil drilling and refining firms. Other forms of risk are notwanted, but cannot be avoided without hedging. Someone who has ashop, for example, can take care of natural risks such as the riskof competition, of poor or unpopular products, and so on. The riskof the shopkeeper's inventory being destroyed by fire is unwanted,however, and can be hedged via a fire insurance contract. Not allhedges are financial instruments: a producer that exports toanother country, for example, may hedge its currency risk whenselling by linking its expenses to the desired currency. Banks andother financial institutions use hedging to control theirasset-liability mismatches, such as the maturity matches betweenlong, fixed-rate loans and short-term (implicitly variable-rate)deposits.
在金融領(lǐng)域，對沖是指用于減少或回避另外一種投資風(fēng)險的投資。對沖是被設(shè)計為降低意外的投資風(fēng)險為最小的策略，同時也可從投資行為中獲得利潤。典型的說，對沖者可以買進一個他認為低于合理價格的證券或債券等投資，然后結(jié)合這些賣出相關(guān)或類似的證券或債券。這樣，對沖者就不用理會整個市場的波動，而只關(guān)注被低估的投資部分的表現(xiàn)。HolbrookWorking（斯坦福大學(xué)的經(jīng)濟學(xué)家），對沖理論的先驅(qū)，稱這種策略為從根本的投機，這個根本就是對沖理論價值與實際價值的差別。
在商業(yè)行為中本來就有風(fēng)險。有些是天生的，如油田或煉油公司對油價漲跌的變化。有些是意料之外的，不使用對沖就不可以被避免的。如某人是個店主，他可以處理好競爭，低質(zhì)量或不流行的貨物，但是無法避免倉庫的火災(zāi)，他可以買火災(zāi)保險作為對沖。不是所有的對沖都是金融產(chǎn)品，如生產(chǎn)者出口產(chǎn)品去別的國家可以賣出該國貨幣至所需的貨幣，這樣即使將來該國貨幣貶值，生產(chǎn)者也避免了損失。銀行和其他金融機構(gòu)也使用對沖來控制資產(chǎn)負債的不匹配，如到期支票和應(yīng)付款，固定比例的貸款和短期（不定期的）存款。
對沖交易
Example hedge
A stock trader believes that the stock price of FOO, Inc., willrise over the next month, due to this company's new and efficientmethod of producing widgets. He wants to buy FOO shares to profitfrom their expected price increase. But FOO is part of the highlyvolatile widget industry. If the trader simply bought the sharesbased on his belief that the FOO shares were underpriced, the tradewould be a speculation.
Since the trader is interested in the company, rather than theindustry, he wants to hedge out the industry risk by short sellingan equal value (number of shares × price) of the shares of FOO'sdirect competitor, BAR. If the trader were able to short sell anasset whose price had a mathematically defined relation with FOO'sstock price (for example a call option on FOO shares) the trademight be essentially riskless and be called an arbitrage. But sincesome risk remains in the trade, it is said to be "hedged."
The first day the trader's portfolio is:
Long 1000 shares of FOO at $1 each
Short 500 shares of BAR at $2 each
(Notice that the trader has sold short the same value ofshares.)
On the second day, a favorable news story about the widgetsindustry is published and the value of all widgets stock goes up.FOO, however, because it is a stronger company, goes up by 10%,while BAR goes up by just 5%:
Long 1000 shares of FOO at $1.10 each — $100 profit
Short 500 shares of BAR at $2.10 each — $50 loss
(In a short position, the investor loses money when the price goesup.)
The trader might regret the hedge on day two, since it reduced theprofits on the FOO position. But on the third day, an unfavorablenews story is published about the health effects of widgets, andall widgets stocks crash -- 50% is wiped off the value of thewidgets industry in the course of a few hours. Nevertheless, sinceFOO is the better company, it suffers less than BAR:
Value of long position (FOO):
Day 1 — $1000
Day 2 — $1100
Day 3 — $550 => $450 loss
Value of short position (BAR):
Day 1 — $1000
Day 2 — $1050
Day 3 — $525 => $475 profit
Without the hedge, the trader would have lost $450. But the hedge -the short sale of BAR - gives a profit of $475, for a net profit of$25 during a dramatic market collapse.
對沖交易
一個股票交易員相信foo的股票價格下個月將上升，因為這個公司使用了新式的更有效的方法生產(chǎn)。他想買foo股票來獲取價格上漲的利潤。但是foo的行業(yè)產(chǎn)品市場是反復(fù)無常的。如果交易員買入股票只是簡單的根據(jù)foo股票價格被低估的理念，這個交易極有可能是失敗的投機。
因為交易員對這個公司更感興趣，他可以通過賣出等值的直接競爭者bar的股票來對沖掉行業(yè)風(fēng)險。如果交易員能夠賣空在與foo的股票等值的資產(chǎn)(如看漲期權(quán)對foo股票)的，交易可能會基本上是無風(fēng)險的，被稱為套利.但由于某些風(fēng)險依然存在,在交易,他們說是"對沖"。
第一天這個交易員的賬戶:
多單1000股foo,單價$1
空單500股，單價$2
(注意空單和多單等值：股數(shù)*價格)
第二天,行業(yè)利好消息出臺，foo作為行業(yè)較強公司，漲10%，bar漲5%
賬戶情況如下：
多單1000股foo,單價$1.1利潤：$100
空單500股，單價$2.1 損失：-$50
交易員第二天可能會后悔，因為對沖減少了收益。但是第三天行業(yè)不利消息出臺，全行業(yè)損失50%，因為foo較好，所以跌的也比bar少：
賬戶情況如下：
多單：
第一天：$1000
第二天：$1100
第三天：$550
損失：$450
空單:
第一天：$1000
第二天：$1050
第三天：$525
利潤：$475
如果沒有對沖，交易員可能損失$450，但是對沖賺了$475,最終在戲劇性的市場崩潰中凈賺了$25我們常在外匯市場中見到的對沖交易有--非美高息之間的對沖，如這次美國次按風(fēng)波，作歐元多的時候，補一手NZD放空就是防范集體的風(fēng)險，和鎖倉是不一樣的。但是，具體的技巧需要更多的實踐來檢驗。投機中的對沖雖然減少了利潤，但是或許是獲取穩(wěn)健收益的一條金光大道。需要注意的是，利用不同的止損和止贏的策略是不同于簡單的交叉盤保值做法。
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