Calendar Spread
A calendar spread sells a near-term option and buys a longer-term one at the same strike, profiting from faster near-term decay. Learn how this time-based trade works.
A calendar spread sells a near-term option and buys a longer-term option at the same strike. It profits from the fact that the near-term option you sold decays faster than the longer-term one you own. It is a bet on time, not direction.
Where a vertical spread stacks two strikes on one date, a calendar stacks two dates on one strike. That is why it is also called a horizontal or time spread. Let me show you the engine that drives it.
Two Ice Cubes Melting at Different Speeds
Every option is a melting ice cube, losing time value as expiration nears. The trick of a calendar spread is that the two ice cubes melt at different speeds.
The near-term option you sold melts fast, because decay accelerates in the final weeks. The longer-term option you bought melts slowly, with lots of time still on its clock. You collect the fast melt on the short option while barely paying for the slow melt on the long one. That difference is your profit, and it lands most cleanly when the stock sits near the strike.
Watch It Work
Apple is at $200 and you expect it to hover there for the next month. You build a calendar spread at the $200 strike:
- Sell the 30-day $200 call for $5 a share
- Buy the 90-day $200 call for $8 a share
- Net cost: $3 a share, or $300, your maximum risk
Apple sits near $200 as the near-term expires. The 30-day call you sold decays to almost nothing, so you keep most of that $5. Your 90-day call has barely lost value because it still has 60 days left. You can close the trade for a profit or sell another near-term call against your long option and do it again.
Apple makes a big move to $230 or $170. Both options move roughly together, and the spread's edge shrinks. A calendar wants the stock to stay put, so a large move in either direction is the losing case. Your loss is limited to the $300 you paid.
What Makes It Tick
A calendar spread has two engines, and both matter.
Time decay. The near-term option melts faster, which is the core profit driver when the stock stays near the strike.
Volatility. Because your long option has more time, it carries more vega, so a calendar is generally long volatility. A rise in implied volatility helps you, and a drop hurts, which makes calendars a favorite for entering when volatility is low and expected to climb.
The ideal outcome is a stock that pins the strike while volatility rises. The enemy is a big directional move that pulls both options away from the strike.
- A calendar spread sells near-term and buys longer-term at the same strike.
- It profits from the faster decay of the near-term option.
- It wants the stock to stay near the strike.
- It is generally long volatility, helped by rising IV.
Pop Quiz
Three quick questions to see what stuck. Pick an answer and the explanation shows up right away.
What does a calendar spread profit from?
You sell the fast-decaying near-term option and own the slow-decaying long one, harvesting the difference.
Where does a calendar spread want the stock to be?
The edge is largest when the stock pins the strike, letting the short option decay while the long one holds value.
How does rising implied volatility affect a calendar spread?
The longer-term option carries more vega, so a calendar is generally long volatility and benefits when IV rises.
Bottom Line
A calendar spread is a bet on time and stillness. Sell a fast-decaying near-term option, own a slow-decaying longer-term one at the same strike, and profit as the difference works in your favor while the stock stays near the strike.
It adds a second engine too: with more time on the long leg, the trade is long volatility, so it rewards a stock that goes quiet while fear ticks up. A big move is the one thing it does not want.
Keep going: add a directional lean with the diagonal spread, flip the bet with the reverse calendar spread, and revisit the decay that drives it in time decay.