Double Calendar: Two Strikes, Two Expirations, Four Legs

For educational purposes only; not investment advice.

Direct answer

A double calendar combines two long calendar spreads at different strikes. At each strike, it sells a nearer-dated option and buys an equal number of later-dated options of the same type. A common neutral construction uses puts at a lower strike and calls at a higher strike, producing four legs and two price areas around which the position may retain value at the front expiration.

It is usually a net-debit, defined-risk structure at entry, but it is not an iron condor. The near options expire first while the far options remain alive, so front-expiration profit depends on the far options’ time value and implied volatility. There is no single fixed maximum-profit formula or pair of breakevens known at entry.

Structure and exposure

With lower strike K₁, upper strike K₂, front expiration T₁, and back expiration T₂, one common structure is:

Sell one K₁/T₁ put and buy one K₁/T₂ put.
Sell one K₂/T₁ call and buy one K₂/T₂ call.

Each pair is a calendar spread because type and strike match while expiration differs. The front options often decay faster, while the back options provide longer-lived Vega and time value. Net Theta and Vega are not permanent: spot, time, volatility term structure, and skew can change the balance, and front Gamma can become dominant near T₁.

At T₁, the trader can close all four legs beforehand, buy back the front legs and retain the back strangle, or roll one or both short legs. A roll closes an old risk and opens a new one; it does not erase the original result.

Four-leg numerical example

Assume the stock is $100:

Sell a 30-day $95 put for $1.60; buy a 90-day $95 put for $3.40.
Sell a 30-day $105 call for $1.50; buy a 90-day $105 call for $3.20.

The net debit is $3.50 per share, or $350 with a 100-share multiplier. For the unadjusted package, the theoretical maximum loss is generally the debit if all four options ultimately provide no offsetting value, excluding costs and operational failures.

At the front expiration, suppose the stock is $100, both short options expire worthless, and the remaining $95 put and $105 call are quoted at $1.80 and $1.90. The package is worth $370, an illustrative $20 gain before costs.

If the stock is $110, the short $105 call has $5.00 intrinsic value, while the back call and put are assumed to be worth $7.20 and $0.20. Net package value is $7.20+$0.20−$5.00=$2.40, or $240, an illustrative $110 loss. A symmetric downside scenario can differ because put skew and volatility may change. All back-option prices are scenario assumptions, not guaranteed marks.

The two strikes can create two local value peaks, but their height and the valley between them depend on remaining time, the two expiration surfaces, and execution prices. Moving the strikes farther apart does not automatically create a safer or wider profitable range.

Risk checklist

Enter and exit with a four-leg complex limit order where practical; separately filled legs can change the debit and Greeks.
Verify option type, strike, expiration, quantity, multiplier, settlement, and adjusted deliverable for every leg.
Model the full front-expiration surface using back-option values, not a standard one-expiration payoff diagram.
Stress independent moves in front and back implied volatility, skew, and term structure.
Monitor early assignment of American-style short options, especially calls before ex-dividend dates and deep-in-the-money puts.
Do not assume assignment automatically exercises the corresponding back option.
Decide before T₁ whether to close, retain, or roll each leg; include after-hours and pin risk.
Treat the remaining back strangle as a new long-volatility position after the short legs expire.
Include four-leg bid-ask spreads, commissions, financing, taxes, and broker margin treatment.

Common misconceptions

“It is an iron condor with different dates.” An iron condor has one expiration and a fixed expiration payoff; a double calendar does not.
“Profit is guaranteed between the two strikes.” Far-option values and volatility can make the center profitable or unprofitable.
“The maximum gain is known at entry.” It depends on the surviving options’ value at management time.
“Positive Theta and Vega stay constant.” Net Greeks change and can reverse as spot and time move.
“The initial debit is the only cash need.” Assignment can create temporary stock, margin, and financing requirements.
“Rolling the short legs lowers cost basis without consequence.” It realizes one trade and adds a new expiration risk.