主题：Call/Put option & Strike Price -- 罗格
最近在玩Cash Flow电脑游戏，里面的Call/Put option & Strike Price搞得我头晕脑胀。请哪位高人给讲讲什么意思吧。Option是要花钱买的吗？为什么游戏里电脑逼着我还钱好像我在炒期货一样？这东西跟国内的期权是一个概念吗？国内的期权怎么交易？问题太多，先谢谢了。
To simplify these situation we assume that there's no premium need for both case.
Call option allow you to choose whether or not to purchase the asset.
If you purchased a call option with a strike price K, then at the expiration date, if the price of the stock(St) is greater than your K, then you can buy the asset. Because, the profit of the call option is St - K (If St>K) and 0 (If St<=K).
Put Option allow you to choose whether or not to sell the asset.
In this case, if you purchased a put option with a strike price K, then similiarly, at the expiration date, if the price of the asset(Say St) if less than you K, then you can sell the asset. Because, the profit of the put option is (K - St)(If St<K) and 0 (If St>=K).
PS.Usually, you will puy premium for purchasing a Call/Put option at the beginning, if you choose not to exercise your "option", you will lose your premium.
PS2.If you sell a Call/Put option, you will receive premium from buyer, but at the end you will have to exercise (which means buy or sell) the asset at the strike price in your agreed option.
Thanks. Then who will, for what reason offers such a offer. Could you please give an example in China domestic stock market.
配股权证可以买卖么？
任何人可以卖（write)options。电脑游戏逼你还钱的话，你肯定卖来着。假如只买的话，你不需要在任何时候还钱，最多把本儿丢光！
当你卖option的话，你手里得有一些钱或者股票。Depending on the margin rate, you don't need the full amount required to cover the whole thing, just a portion of it. Say stock A is at $10 a share now, you decided to write a July 1st 12.50 call for $3. The buyer buys the RIGHT to buy this stock @ 12.50 a share from you any time before and on July 1st. If the thing took off and went to $20 a share in April, technically the buyer can demand to buy the stock from you at the stricking price. If you have the amount of stock required in your account, you don't have to worry a thing. But if you are writing options naked - without underlying stocks - then you need to have enough money in your account to buy those stocks to cover your option. When the stock prices go up, you need more and more money.
It's simpler with Puts. You just need to have the money when people decided to sell you the stock.
据统计 30% Option到期时一文不值。(not over 50%, got my number wrong)
Even if they don't have any share on hand?
You need to ask specific questions. Otherwise, get some basic understanding of option trading by visiting this website: Investopedia's intro to option trading