Calendar spread

Profits and losses

Since the calendar spread involves two expiry months, it is not possible to construct an accurate payoff diagram for the strategy at expiry of the sold option. The value of the long option at this point can only be estimated using pricing models. However, the maximum profit will be realised if the share price is at the strike price of the options at the first expiry. The sold call will then expire worthless, while the long call will have the most possible time value remaining.

The calendar spread benefits from the different rate of time decay of the two options involved. Time decay of the near month option's premium will be faster than that of the far month option. This has the effect of widening the spread between the two prices. 

The maximum loss possible is the cost of the spread. This will occur if the long call has very little time value left at expiry, in other words if the share price has either risen or fallen dramatically.

Other considerations

• Exercise: if the share price rises, both legs will come into-the-money. In this case, the trader faces the possibility of early exercise on the short leg. The long leg acts as a hedge, but the cost and inconvenience of being exercised must be considered.
• Buying stock cheaply: the calendar spread can be used as a way of acquiring stock below the current market price. If an investor expects the share price to rise, but does not foresee this taking place within the next month, buying a calendar spread effectively gives the investor a call option once the near month expiry has passed, however at a lower cost than taking a call outright.
• Volatility: an increase in short term volatility can be damaging to the calendar spread, since it works against the desired fall in value of the sold call option.

Follow-up action

If the market remains steady, the investor may choose to do nothing and let time decay take its course, resulting in the short call expiring worthless. The investor can then close out the long call or perhaps hold on to it if expectations are now bullish. Holding the call converts the strategy to a simple taken option position, with the attendant risks and rewards. 

If the stock falls unexpectedly, the investor may choose to close the spread before the long call loses all time value. Otherwise, the position could be left in the hope that the market recovers and the long call improves in value. 

In the event of a market rise, the investor must decide whether to close out the spread to avoid exercise or maintain it in the hope that the market retreats and time decay can take effect.

• Take advantage of time decay by entering the spread around six weeks before expiry of the near-term option.
• Be wary of leaving the taken call open after expiry of the sold option. If this is the case then the position becomes a different strategy.