Calendar put spread
A systematic options approach—Calendar put spread—defined by explicit rules, testable on history, and fragile when costs or regimes change.
Overview
This is a horizontal spread consisting of a long position in a close to ATM put option with TTM T′ and a short position in another put option with the same strike price K but shorter TTM T < T′. The trader’s outlook is neutral to bearish.
Calendar put spread sits in the Options chapter of the systematic catalog. On QUSXFI we treat it as a testable hypothesis: specify entries, exits, sizing, and costs—then ask whether edge survives out-of-sample scrutiny.
Discretionary traders often arrive at similar ideas intuitively; the quantitative version forces you to write the rule before you see the next bar. That discipline is what makes results reproducible—or exposes them as luck.
Based on the research catalog 151 Trading Strategies (Kakushadze & Serur, 2018), section 2.19. Educational summary—not a replication of the full formal definition.
Term-Structure Logic
Calendar put spread trades calendar or diagonal structure—theta and term-structure moves dominate direction in calm tapes.
Map every input Calendar put spread needs in Options—prices, vol surfaces, fundamentals, or legal milestones—and verify point-in-time integrity.
Implementation and Research Process
Model roll mechanics on Calendar put spread explicitly; calendar P&L is roll timing as much as theta.
For §2.19 Calendar put spread, write the rule set so another researcher could replicate without you in the room.
Stress Calendar put spread costs at 2× baseline; many Options edges live or die on slippage alone.
Risk: What Breaks This Strategy
Calendar put spread separates calendar risk from direction, but front-month vol shocks can hurt both legs if the term structure inverts violently.
Rolls around events can invert the edge you backtested on smooth historical surfaces.
Theta harvest can look stable until a single name event gaps through both expiries.
Common Mistakes to Avoid
- Deploying Calendar put spread live before paper trading through at least one adverse Options month.
- Confusing Calendar put spread theta harvest with a vol-neutral free lunch.
- Confusing this educational Calendar put spread summary with compliance-approved investment advice.
- Reporting Calendar put spread backtests without fees, slippage, and realistic fill rules.
How to Study This Strategy
- Restate Calendar put spread (§2.19) as numbered rules another researcher could implement cold.
- Map Calendar put spread to Basic Trading chart concepts you will use as filters—not as substitutes for rules.
- Add conservative costs to Calendar put spread; rerun with 2× spreads and compare drawdown paths.
- List every data field Calendar put spread needs in Options; verify point-in-time integrity.
- Write a one-page Calendar put spread failure memo: three break modes and early warning signs.
Key Takeaways
- Calendar put spread isolates term-structure and theta from raw direction—until front-month events invert the curve you modeled.
- Roll cadence on Calendar put spread must specify event blackouts; earnings in the front leg rewrite the thesis.
- Smooth historical surfaces hide violent inversions around macro prints.
- Theta harvest on calendars can look stable until one gap through both expiries.
- Compare Calendar put spread to outright vol trades in the sidebar—time spread is not a free vol-neutral lunch.
Learning Tip
File a dated note after each Calendar put spread paper session: what worked, what broke, what you will not override next time.
Explore related strategies in the sidebar or return to the full catalog.