Stock Options 

How Do Stock Options Work

Stock options trading refers to trading of contracts to buy (or sell) a stock for a certain price at a certain time in the future. Buyers of stock options have the right to buy the stock at the specified price, but they are not obligated to exercise their option. Sellers of options have the obligation to sell the underlying stock if the buyer of the option wishes to exercise it.

Call Options

A contract to buy is called a 'call option'. The buyer of a call option hopes the price of the underlying stock will rise, allowing him to buy it at less than market value. The seller of the call option expects that the price of the stock will not rise, or at least is willing to accept a partial loss of profits made from selling the call option.

For example: An investor buys a call option on IBM with a 'strike price' (the price the stock can be bought) of $50. The current price of IBM stocks is $40 and the cost of the call is $5. If the price rises above $55 (strike price + cost of call) the buyer could exercise his right to buy and make a profit by reselling on the open market. The seller would still gain from the increase in price from $40 to $55 plus the $5 he made by selling the call. If the price remains below $55 the call would not be exercised and the seller would profit by $5 per share and the buyer would lose his $5 per share.

Stock option trading is permitted on select stocks. The stock options (buy/sell) detail the name of the stock, the strike price (the price the stock can be bought or sold at), the expiration date and the premium (the price of the option itself). After the expiration the option cannot be exercised and is worthless. Options have a value and are actively traded. An option to buy Microsoft, for example, is listed like this:

MSFT Jan '06 22.50 Call at $2.00

This tells us that an option to buy 1 share of Microsoft at $22.50 before the third Friday in January 2006 can be bought for $2.00. Options usually expire on the third Friday of the specified month, and they are usually traded in lots of 100. To buy this particular option you would have to pay $200 (plus brokerage fees).

Put Options

An option to sell a stock is called a 'put option'. This gives the holder the right (but not the obligation) to sell a particular stock within a certain time period at a certain price. In this situation the buyer is expecting the price of the stock to fall but does not want to sell outright in case the price rebounds. The seller feels that the price is stable or is willing to acquire the stock at the low price.

For example: An investor buys a put option on Microsoft with a 'strike price' (the price the stock can be sold) of $35. The current price of Microsoft is $40 and the cost of the put is $5. If the price falls below $30 (strike price + cost of put) the buyer could exercise his right to sell at a higher price than market. The seller would have to buy the stock at the higher-than-market price but any losses are offset by the $5 he made by selling the put. If the price remains above $30 the put would not be exercised and the seller would profit by $5 per share and the buyer would lose his $5 per share.

Principles of Stock Option Trading

As can be seen, stock option trading can be used to protect against loss or as an investment opportunity in their own right. They are generally used as part of a stock trading strategy which combines the purchase of stock with the purchase of options.

For example, in a bull (rising) market you could buy stocks and call options and sell put options. This allows you to take full advantage of rising stock prices – the stocks you buy will rise in value, the call options will allow you to buy stock at less than market prices, and if the market dips and the buyer of your put option exercises it, you can pick up additional stocks at low prices. If the buyer does not exercise the option, you make money from the sale of the option.

Conversely, in a bear market, you can sell stocks, sell calls, and buy puts to limit losses and generate profits. Unstable markets can use a mixture of puts and calls to maximize profit potential.

Stock option trading takes place on Futures and Options Exchanges. There are 6 such exchanges in the United States including the American Stock Exchange (AMEX) and the Chicago Board Options Exchange (CBOE). In Europe the main options exchanges are Euronext.liffe and Eurex.