Covered call

A covered call is a financial market transaction in which the seller of call options owns the corresponding amount of the underlying instrument, such as shares of a stock or other securities. If a trader buys the underlying instrument at the same time the trader sells the call, the strategy is often called a "buy-write" strategy. In equilibrium, the strategy has the same payoffs as writing a put option.

The long position in the underlying instrument is said to provide the "cover" as the shares can be delivered to the buyer of the call if the buyer decides to exercise.

Writing (i.e. selling) a call generates income in the form of the premium paid by the option buyer. And if the stock price remains stable or increases, then the writer will be able to keep this income as a profit, even though the profit may have been higher if no call were written. The risk of stock ownership is not eliminated. If the stock price declines, then the net position will likely lose money.

Since in equilibrium the payoffs on the covered call position is the same as a short put position, the price (or premium) should be the same as the premium of the short put or naked put.

Trader A ("A") has 500 shares of XYZ stock, valued at $10,000. A sells (writes) 5 call option contracts, bought by Investor B ("B") (in the US, 1 option contract covers 100 shares) for $1500. This premium of $1500 covers a certain amount of decrease in the price of XYZ stock (i.e. only after the stock value has declined by more than $1500 would the owner of the stock, A, lose money overall). Losses cannot be prevented, but merely reduced in a covered call position. If the stock price drops, it will not make sense for the option buyer ("B") to exercise the option at the higher strike price since the stock can now be purchased cheaper at the market price, and A, the seller (writer), will keep the money paid on the premium of the option. Thus, A's loss is reduced from a maximum of $10000 to [$10000 - (premium)], or $8500.

This "protection" has its potential disadvantage if the price of the stock increases. If B exercises the option to buy, and the stock price has increased such that A's shares of XYZ are now worth more than $10,000 in the market, A (the option writer) will be forced to sell the stock below market price at expiration, or must buy back the calls at a price higher than A sold them for.

If, before expiration, the spot price does not reach the strike price, the investor might repeat the same process again if he believes that stock will either fall or be neutral.

...
Wikipedia