Strike price is the fixed price at which holder of a call option can buy the underlying asset irrespective of its market price until the expiration of contract.
For a put option holder, it is the price at which underlying assets can be sold until the expiration of contract.
The strike price is determined at the time of entering into a derivative contract.
In a call option, if it remains lesser than the spot price (market price), the holder can exercise the option to earn profit.
On the other hand, in a put option, the holder of the option can earn profit only if strike price is more than the market price.
Example of strike price:
On 1st January 2018, Mr A entered into a derivative contract to buy 100 shares of company XYZ Ltd at a strike price of INR 85. The expiration date of contract is 3 months i.e. 31st March 2018. On 1st of January the market price was INR 82.
In the month of February, market price increased from INR 82 to 97. Mr A has the right to purchase the 100 shares of XYZ ltd at a price of INR 85 or Mr A can wait for further hike in share price till the expiration of contract.
In the month of February, market price increased from INR 82 to 97. Mr A has the right to purchase 100 shares of XYZ ltd at a price of INR 85 or Mr A can wait for further hike in price till the expiration of contract.