Reverse Calendar Spread at a glance
| Construction | Buy 1 call at the money in the front month and sell 1 call at the money in the next month. |
|---|---|
| Outlook | Big move either way |
| Volatility view | Wants falling IV |
| Max profit | Approximately the net credit received, times 100, reached when the stock moves far from the strike by front month expiration. |
| Max loss | Value of the back month call at front month expiration with the stock at the strike, minus the net credit, times 100, assuming you close both legs then. |
| Breakeven | There are two breakevens, one on each side of the strike, where the back month call's estimated value minus the front month call's intrinsic value equals the net credit at front month expiration. |
| Experience level | Advanced |
| Also called | Short calendar spread, Short call calendar |
How a reverse calendar spread works
The reverse calendar spread is the opposite of a long call calendar. You sell the more expensive next month call and buy the cheaper front month call at the same strike, collecting a net credit. If the stock makes a large move before the front month expires, the two calls converge: far below the strike both become nearly worthless, and far above it both trade close to intrinsic value. Either way the spread you sold shrinks and you keep most of the credit.
The payoff is shown at front month expiration, when your long call is worth its intrinsic value and the short back month call still has time value. The graph is an inverted tent: the worst point is near the strike, where your front call expires worthless and the short call holds its most time value, and profit flattens toward the credit as the stock moves away. Because that shape depends on the back month call's value, the calculator estimates the max loss and breakevens with an American pricing model.
Before front expiration, time works against you near the strike, since the call you own decays faster than the call you sold. Implied volatility is the other driver: the short back month call has more vega, so a volatility drop helps and a rise hurts. The trade fits when back month volatility looks inflated and a large move seems likely, but a still stock combined with rising volatility hits it from both sides.
Reverse Calendar Spread example with real numbers
With the stock at $100, implied volatility at 30%, a 4.1% risk free rate and no dividend, you would buy 1 100 call (32 days) at $3.73, sell 1 100 call (60 days) at $5.19. That is a net credit of $146. At the front month expiration, the model estimates a maximum profit of $146 and a maximum loss of $201, with breakevens at $95.17 and $105.98. The lognormal chance of profit is 55%.
These are theoretical American option prices from the Bjerksund and Stensland model, not live quotes. Load any ticker in the reverse calendar spread calculator above to run the same math on real market prices.
When to use a reverse calendar spread
- You expect a large move in either direction before the front month expires.
- Back month implied volatility looks elevated and you expect it to fall.
- You want a volatile trade that collects a credit instead of paying for a straddle.
- You plan to close both legs at or before front month expiration rather than hold the short call alone.
Max profit, max loss and breakeven
Maximum profit
Approximately the net credit received, times 100, reached when the stock moves far from the strike by front month expiration. If the stock finishes deep in the money, any time value left in the short back month call trims this slightly, so the calculator estimates it with an American model.
Maximum loss
Value of the back month call at front month expiration with the stock at the strike, minus the net credit, times 100, assuming you close both legs then. This is a model estimate, and if you hold the short back month call after your long front call expires, it becomes a naked short call with unlimited risk.
Breakeven
There are two breakevens, one on each side of the strike, where the back month call's estimated value minus the front month call's intrinsic value equals the net credit at front month expiration. They move with implied volatility, so they are estimates from the calculator's American model.
Reverse Calendar Spread Greeks
- Delta: Delta is near zero at entry. It becomes positive as the stock rises and negative as it falls, because the long front call gains and loses delta faster than the short back call.
- Gamma: Gamma is positive, coming from the long front month call, and it grows as front expiration approaches. This is what lets a large move turn into a profit.
- Theta: Theta is negative near the strike, since the call you own decays faster than the call you sold. Every quiet day costs money.
- Vega: Vega is negative because the short back month call is more sensitive to implied volatility. A drop in volatility helps, and a rise hurts.
See the live numbers for your position in the Greeks tab of the calculator, or explore a single option in the options Greeks calculator.
Early exercise and assignment risk
In a reverse calendar the short leg is the longer dated call, and because your long call expires first, most brokers treat that short call as uncovered and charge naked call margin. Early assignment is less likely on a back month call because it carries more time value, but it can still happen the day before an ex dividend date if the call is deep in the money and the dividend exceeds its remaining time value. If assigned, you are short 100 shares, covered by your front month call until it expires.
Holding the long front month call also gives you a choice: if it is deep in the money before an ex dividend date, exercising it to own shares can make sense, since the shares then cover the short back month call and you receive the dividend. The biggest American style risk comes at front month expiration. Close the short back month call when the long call expires, or you will be left holding a naked short call with unlimited risk.
The calculator's Early exercise risk tab flags short legs that are likely to be assigned. For a single option, use the early exercise calculator or read how early exercise and assignment work.
Pros and cons
Pros
- Collects a credit and profits from a large move in either direction.
- Benefits from a decline in implied volatility, the opposite of a long calendar.
- Loss is limited while both legs are open, as long as you close at front month expiration.
- Useful for fading an inflated back month volatility level.
Cons
- Most brokers require naked call margin on the short back month call.
- Loses money if the stock stays near the strike while time passes.
- Rising implied volatility hurts the position.
- Holding past front month expiration leaves an uncovered short call with unlimited risk.
How to manage a reverse calendar spread
- Close both legs together at or before front month expiration so the short call is never left naked.
- If the stock moves far from the strike quickly, consider taking the profit early rather than waiting.
- Before an ex dividend date, check whether either call is deep in the money and close, roll or exercise as appropriate.
- Size the trade around the naked call margin, which can be much larger than the credit received.
Reverse Calendar Spread FAQ
What is a reverse calendar spread?
A reverse calendar spread buys a near term option and sells a longer term option at the same strike, collecting a net credit. It profits when the stock moves far from the strike or implied volatility falls. It is the opposite of a long calendar spread.
Is a reverse calendar spread risky?
A reverse calendar spread has limited risk only while both legs are open; once the front month call expires, the remaining short call is uncovered. Most brokers already treat it as a naked short call for margin. Traders who use it plan to close both legs at or before front month expiration.
When does a reverse calendar spread make money?
A reverse calendar spread makes money when the stock moves well away from the strike before front month expiration or when back month implied volatility falls. It loses most when the stock stays at the strike and volatility rises. The calculator shows how both factors change the estimated P/L.
How does a reverse calendar compare with a long straddle?
Both profit from a large move, but a reverse calendar collects a credit and caps its profit near that credit, while a long straddle pays a debit and has unlimited upside. The reverse calendar is short vega, so it can gain when volatility falls, whereas a long straddle loses. That makes it a different bet on volatility, not just a cheaper straddle.
Related strategies
Call Calendar Spread
A calendar spread sells a near term option and buys a longer dated option at the same strike, and it profits most when the stock sits near that strike as the short option expires.
Long Straddle
A long straddle is the purchase of a call and a put at the same strike and expiration, usually at the money.
Reverse Iron Butterfly
A reverse iron butterfly is a defined risk long volatility strategy that buys an at the money put and call and sells an out of the money put and call to cut the cost.
Short Call Condor
A short call condor is a four leg credit spread built with calls that profits when the stock makes a large move in either direction by expiration.
Educational tool, not financial advice. Calculations are theoretical and depend on your inputs; real fills, fees, early assignment and dividends can change results. Options involve risk and are not suitable for every investor.