Calendar Spread

What is a calendar spread?

A calendar spread is an options strategy that combines calls or puts at one strike across two expirations. A long calendar buys the farther-dated option and sells the nearer-dated option, and it can profit when the near option loses value faster than the far option. The shared strike keeps the price reference fixed while the two maturities create different time-value exposures.

A call calendar and a put calendar use the same structure. Both legs match the underlying, option type, contract deliverable, and quantity. The position is also called a time spread or horizontal spread.

How to calculate calendar spread profit and loss

At any management date, subtract the short option’s closing value and the original net debit from the long option’s closing value. Multiply the per-share result by the contract multiplier and quantity.

The example sells a 30-day 100 call for $1.50 and buys a 60-day 100 call for $2.80. One standard calendar costs $130. On day 30, XYZ is $100 and the short call has zero intrinsic value. A $2.40 mark on the remaining call values the position at $240, producing $110 profit.

The $2.40 closing mark is an assumption, not a projection with implied volatility held constant. The longer-dated call still has 30 days remaining, and its value includes both intrinsic and extrinsic value. Use that complete value when plotting the position at the first expiration.

How to choose calendar spread strikes and expirations

Select a strike around the price you want to evaluate at the near expiration. Then compare farther expirations by their entry cost, remaining time, and implied volatility. A strike above or below spot places the calendar’s focus at a different price destination.

Read the volatility term structure across both dates. Map earnings and other scheduled events to the expiration that contains them. This connects the price target with the timing of the trade.

Calendar spread vs vertical and diagonal spreads

A vertical spread changes strikes within one expiration. A diagonal spread changes both strike and expiration. Compare these structures by the price path and management date you want to trade.

Calendar spread Greeks and the profit curve

Compute net Greeks as the long option’s exposure minus the short option’s exposure. Recalculate them at the stock prices and dates in the plan. Test near-expiration and far-expiration volatility separately to see how each maturity drives the package.

At the near expiration, build a scenario curve from the remaining long option’s value minus the short option’s intrinsic value and the entry debit. Read projected profit, breakevens, and the location of the peak directly from that curve. Repeat the calculation with the volatility inputs you want to compare. The options profit calculator moves the date, price, and volatility inputs to compare the calendar’s complete profit curve.

Managing a calendar spread and early assignment

Use one multi-leg order with a net price limit. Track the executable spread price to evaluate the complete entry or exit. To close, sell the long option and buy back the short option together.

Choose whether to close the package, roll the short option, or retain the long option before the near expiration. A long call kept past day 30 is a fresh $240 position: the calendar has earned its $110 at that mark, and from there the call’s own risk decides the result.

Assignment of a standard short call creates a sale of 100 shares; assignment of a standard short put creates a purchase of 100 shares. The longer-dated option remains open. Include those shares and the remaining option in the management plan.

Risks and limitations of calendar spreads

• The far option’s mark on the near expiration date sets the profit. In the example a $2.40 mark pays $110; a lower implied volatility on that date lowers the mark and the profit with it, so price the curve at the volatility you expect then.
• Set an exit for a large move away from the strike. A move in either direction shrinks the spread’s value, and most of the $130 debit can be lost.
• Price each expiration’s implied volatility separately. A long calendar has positive vega through the far option, so a fall in that expiration’s implied volatility lowers the spread’s value even with the stock at the strike, and the two expirations’ volatilities can move apart.
• An American-style short leg can be assigned early. The shares it creates move dollar for dollar while the farther-dated option’s delta stays below 1, so the hedge is partial until you close the shares.
• Enter and exit with one net limit order. Two legs pay two bid-ask spreads on entry and exit, and rolling the short option adds another round of costs.

Bottom line

When the stock sits at the strike while the front month decays, the $1.30 calendar earns its keep from the gap in time value between the two expirations. Model the profit curve with each expiration’s volatility, and set the management date before you enter.