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What is the Contract Size?

The contract size denotes the quantity of the underlying instrument which the buyer of a call can buy (or the buyer of a put can sell) at an agreed exercise price. The contract size is standardized for exchange-traded options.

Contract size = Quantity of underlying instrument that can be bought/sold on the basis of an option.


A Eurex Exchange option on Siemens AG includes the right to buy or sell 100 Siemens shares (= contract size). The published price of the option, however, always refers to just one share.

For most of the on Eurex Exchange traded equity options the contract size is 100 equities (= default). However, equity options on UK equities have a contract size of 1,000 shares, Italian equity options of 500 or 1,000 shares. Still other contract sizes are possible. In general, you should inform yourself on the contract size of the desired contract before buying options.

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The option price is always based on one share. Given the order shown here an option contract (100 shares) shall be sold at EUR 640.

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