
Paper P4: Advanced Financial Management
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Buying options and selling (writing) options
Exercise price or strike price
Rights and obligations of buyer and seller
Option premium = option price
Options: a zero-sum game
2 Buying options and selling (writing) options
2.1 Exercise price or strike price
The exercise price for an option is the price at which the holder can:
buy the underlying item, in the case of a call option, or
sell the underlying item, in the case of a put option.
With OTC options, the exercise price is agreed between the option buyer and the
option seller. With exchange-traded options, options are available for buying or
selling at a limited range of fixed strike prices, and buyers and sellers agree on the
price at which they will make a transaction in the options at one of these prices.
For example, the following table shows exercise prices that might be available on
the CME exchange for US dollar/euro currency options on a day in August, and the
prices of the most recent transactions in those options.
CALLS PUTS
Expiry: Sep Dec Mar Sep Dec Mar
Strike price:
12200 0.34 2.03 3.22 1.62 3.15 3.91
12300 0.18 1.62 2.81 2.16 3.53 4.49
12400 0.09 1.33 2.44 3.06 4.20 5.12
12500 0.04 1.18 2.11 3.66 4.90 -
Notes
(a) A strike price of 12200 indicates an exchange rate of €1 = $1.2200.
(b) At this date, currency options were being traded at just four strike prices, for
expiry dates in September, December and March.
2.2 Rights and obligations of buyer and seller
Options are bought and sold. The seller of an OTC option is often called the option
writer. Selling an OTC option is often called ‘writing an option’. For exchange-
traded options, it is more usual to refer to ‘sellers’ of options, who have a short
position in the options.
The option buyer or option holder has the right to exercise the option but is not
obliged or contractually required to do so.
On the other hand, the seller or writer of the option is contractually obliged to
sell or buy the underlying item if the option is exercised by its holder.