我想問孖展係咩唻ｇａ？

In finance, a margin is collateral that the holder of a position in securities, options, or futures contracts has to deposit to cover the credit risk of his counterparty (most often his broker). This risk can arise if the holder has done any of the following:

borrowed cash from the counterparty to buy securities or options,
sold securities or options short, or
entered into a futures contract.
The collateral can be in the form of cash or securities, and it is deposited in a margin account. On U.S. futures exchanges, "margin" was formally called performance bond.




Margin buying is buying securities with some of one's own cash together with cash borrowed from a broker. This has the effect of magnifying any profit or loss made on the securities. The securities serve as collateral for the loan. The net value, i.e. the difference between the value of the securities and the loan, is initially equal to the amount of one's own cash used. This difference has to stay above a minimum margin requirement. This is to protect the broker against a fall in the value of the securities to the point that they no longer cover the loan.

In the 1920s, margin requirements were loose. In other words, brokers required investors to put in very little of their own money. When stock markets plummeted, the net value of the positions rapidly fell below the minimum margin requirements, forcing investors to sell their positions. This was one important factor contributing to the Stock Market Crash of 1929, which in turn contributed to the Great Depression.








Example




Jean buys a share in Universal Widgets SA for $100, using $20 of his own money, and $80 borrowed from his broker. The net value (share - loan) is $20. The broker wants a minimum margin requirement of $10.
Suppose the share goes down to $85. The net value is now only $5, and Jean will either have to sell the share or repay part of the loan (so that the net value of his position is again above $10).

孖展交易簡介

投資者買賣證券時，可選擇支付全數金額，或向經紀行借入部分款項。投資者如選擇借入款項，便須在經紀行開設「保證金」（俗稱「孖展」）戶口。投資者就買入證券的總額，所存入的部分款項便稱為「保證金」。經紀行向投資者提供貸款，投資者以購入的證券或存放在孖展戶口的其他證券作為抵押品。投資者出售證券後，須根據孖展信貸的條款償還借款。整項交易的利潤，是購入證券的成本減去出售證券所得，再減去交易費用及孖展貸款利息後所得的數額。

為何進行孖展交易？

一般來說，投資者透過孖展交易以提高購買能力，以及藉著槓桿效應擴大投資額。儘管孖展交易有可能提供更高的回報，但潛在的損失亦會同時倍大。

假設一名投資者以100元買入某隻股份，股價後來升至150元。假如該投資者全數支付購入的股份，投資回報率是50%。但假如按50%的孖展成數(又稱「保證金」比率)購入該股份，即支付50元現金及向經紀行借入50元，最後他的投資回報率便是投入的資金的100%。

然而，股價下跌時，進行孖展買賣便會招致巨大損失。假設以100元購入的股份跌至50元，如該投資者全數支付所購股份，他的投資便會損失50%。但假如他以50%孖展成數買賣，便虧蝕100%或損失所有本金!請不要忘記，槓桿作用既能令投資者賺取厚利，也能令他們損失慘重!

追繳保證金

投資者進行孖展買賣時，除可能招致更大損失外，可能還要承受經紀行追繳保證金的風險。假如孖展戶口內的證券的價值跌至低於預設的孖展成數，經紀行可能要求投資者提供額外的抵押品（俗稱「補倉」）。

投資者應注意，經紀行不一定有責任向客戶發出追繳保證金通知，或通知他們的戶口內的證券的價值已跌至低於指定的孖展成數。經紀行可以隨時出售客戶的證券，毋須事先諮詢他們的意見。若干孖展客戶協議規定，即使經紀行表示會給客戶時間提供抵押品，但該公司仍有權毋需待客戶繳足保證金便出售他們的證券。這種「強迫性斬倉」在出售證券的價格及時間方面都很可能會對客戶不利。此外，假如客戶的抵押品有超過一隻股份，經紀行可能會出售流通量最高的股份，並非客戶打算出售的那隻股份。因此，進行買賣前，投資者必須查詢清楚有關的追繳保證金程序。

投資者必須知道如遇到斬倉，損失可能會超過所存放的孖展金額。假如斬倉後所得的款項仍不足以償還孖展貸款時，投資者除損失所有的孖展存款外，還要承擔該戶口的虧損。

所以本人贊成用孖展方式投資. 貪沒有好結果.