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Summary

Calendar (horizontal) spreads buy a far-dated option and sell a near-dated option at the same strike, making them the only spread family that trades the volatility term structure directly2. Diagonals vary the strike as well as the month, turning the calendar into a delta-tilted income structure. The long calendar profits from the front month decaying faster than the back month — positive theta bought with negative gamma3.

Construction

  • Long calendar: sell near-term option, buy same-strike back-month option. Profit zone is a tent centered on the shared strike.
  • Diagonal: sell near-term option at one strike, buy back-month option at another — e.g., sell a 30-DTE OTM call and buy a 60–90 DTE further-OTM call as a leveraged income trade.
  • Double calendar / double diagonal: run one on each side of the market (calls and puts), producing a condor-like profit plateau with later-month wings2.

Payoff Table

Long calendar — short 30-DTE 100 call, long 90-DTE 100 call, net debit 2.00, evaluated at front expiry:

Underlying at front expiry Position value
Far below strike Small (both nearly worthless; near-net long back vega)
Near 100 (front expires worthless) Maximum — keep the full back-month value
Far above strike Capped/limited — front calls gain, but back calls gain more only after costs

Max loss ≈ debit paid if the underlying moves far from the strike in either direction.

Greeks Profile

Greek Long calendar (same strike) Diagonal (typical income form)
Delta ~flat at entry Tilted by strike offset
Gamma Negative — short the high-gamma front month Negative near short strike
Theta Positive — the harvest Positive
Vega Positive — long-dated options carry more vega Positive

The signature trade is theta-with-vega: unlike the short-premium verticals, calendars gain if IV rises3.

Best Regime / Market View

  • Term structure is the core condition: a long calendar (sell front, buy back) profits when the front month is rich or inverts — i.e., backwardated/front-loaded term structure, or a front-month IV crush relative to the back. Under normal upward contango (front IV below back IV) the long calendar pays away that premium; it is the short calendar that collects it. TOMIC's calendar condition: IV low, good term structure, low skew, 10–30 DTE on the front leg, targeting 5–10% returns in days1.
  • Also a term-structure dislocation trade: sell the rich month, buy the cheap month, regardless of direction.
  • Diagonals suit a gradual, mildly directional drift with the short leg decaying against a still-alive long leg.

Primary Risks

  • Negative gamma: a fast, large move through the shared strike loses on both legs' relative value3.
  • Volatility event on the front leg (earnings) can reprice the whole structure; the back leg only partially hedges.
  • Term-structure inversion — the short month's IV can rise faster than the long month's, hurting the long-vega thesis in the wrong direction.
  • Diagonals: early assignment risk on ITM short legs; wide back-month markets.

Management Levers

  • TOMIC exit rule: never lose more than 10% of margin on a calendar; these are fast, small-target trades1.
  • Close the front leg as it decays, roll it to the next month, or convert a single calendar into a double calendar for a plateau.
  • Adjust the diagonal's short strike up/down to re-center delta as the underlying drifts.

Variants

  • Short calendar (buy front, sell back): the mirror — positive gamma, negative vega. It suits an upward-sloping contango with a cheap front month (collecting the front-to-back premium) or expresses a view that IV will decline3. The long calendar (sell front, buy back) is the structure for a front-rich/inverted term structure, per the regime table above.
  • Double diagonal: calendar + condor hybrid with later-month wings.
  • PMCC-style diagonal: deep-ITM long LEAP + short OTM call as a covered-call surrogate.
  • Jade lizard family: diagonalized short options without an upside (or downside) wing — accepted-tail variants.

Links

Source Notes

  1. TOMIC calendar conditions and exits, ../option-traders-hedge-fund-bundle/topics/strategies.md. ↩↩

  2. Trading Option Greeks, calendar/diagonal family, ../trading-option-greeks/topics/spreads.md. ↩↩

  3. Natenberg on time spreads and sensitivities, ../option-volatility-and-pricing-bundle/topics/spreads.md. ↩↩↩↩