Chapter 8 of 8

Playbook: a defined-risk bear put spread

Build a bearish debit-spread hypothesis without confusing a capped expiry payoff with a guaranteed easy exit.

4 min read · Strategy research candidate

Rule sheet · Original paper-research candidate

The playbook at a glance

Market conditions: A separately evidenced bearish thesis; matched same-expiry puts with adequate liquidity.
Setup & entry trigger: Frozen underlying-breakdown rule and acceptable net debit under a contemporaneous execution model.
When the idea fails: The specified underlying reclaim or thesis failure; separate executable spread-loss trigger.
Position sizing: Matched whole lots, debit plus costs, portfolio heat and funding requirements.
Exit policy: First registered reclaim/invalidating event, debit-loss trigger or pre-expiry deadline; close both legs.
When to skip: Excessive debit, missing executable quotes, leg mismatch, unclear delivery or inability to fund obligations.

These rules are unvalidated research candidates, not a claim of positive expectancy. Parameter choices are illustrative. Test costs, gaps and funding before interpreting a result.

Download the research log template ↓

In this chapter

Bearish exposure with a bounded matching expiry diagram
Register the price trigger and maximum debit
Write the payoff rather than memorising a label
Plan for a rebound and an incomplete fill
Evaluate costs, selection and downside scenarios
Worked example
Common mistakes
Check your understanding

Bearish exposure with a bounded matching expiry diagram #

Buy a higher-strike put and sell a lower-strike put on the same underlying, expiry and matched units. The net debit buys a bearish terminal exposure with capped gain. The candidate can lose its full debit if the underlying does not fall sufficiently or soon enough. A frightening headline does not provide the probability distribution needed to evaluate that debit.

Write whether the thesis concerns a short-lived liquidity event, a longer earnings revision or a price-structure failure. The expiry and intended exit must be compatible with that hypothesis. “Bearish eventually” is not enough for a time-limited option position.

Register the price trigger and maximum debit #

A research version can use a completed downside break of a level fixed before the signal, then evaluate the spread at the next eligible execution point. Specify the upper and lower put strikes in relation to that frozen scenario and define the maximum debit. Do not select the historically best strikes after observing where the underlying ended.

Record contemporaneous executable quotes. High implied volatility around an event can make a bearish premium expensive; a subsequent underlying decline need not offset a volatility contraction before expiry. A spread changes sensitivities, but does not abolish them.

Write the payoff rather than memorising a label #

For lower strike Kₗ and upper strike Kₕ, P&L per unit at expiry is max(Kₕ−S,0) − max(Kₗ−S,0) − D. Maximum matching expiry loss is debit D, maximum matching expiry gain is Kₕ−Kₗ−D, and breakeven is Kₕ−D, before costs. The formula assumes the two legs remain correctly matched.

The maximum-profit zone occurs at or below the lower strike at expiry. It is not the amount you automatically receive if the underlying touches the lower strike several days earlier. Pre-expiry prices still reflect remaining optionality, quotes and liquidity.

Plan for a rebound and an incomplete fill #

For a specified paper version, close both legs if the underlying closes back above the frozen breakdown level, if the executable net spread value falls to half the debit, or at the registered pre-expiry exit deadline. Record when each condition becomes observable and which next execution is available. A close-based condition does not authorise an earlier fill at that session’s closing price without an order-execution model.

A partial fill can leave an outright option instead of a spread. Set a maximum time or execution state for completing or unwinding the intended structure and model the unfavourable fill. Short-first execution can create a materially different exposure; a backtest cannot wish the missing long put into existence.

Evaluate costs, selection and downside scenarios #

Register both winning and losing candidates, and include the spread and fees on four transactions if both legs are opened and later closed separately. Analyse a slow decline, a fast decline, no move, a gap rebound and a volatility contraction. The method may be poorly suited when the maximum debit consumes too much of the strike width.

Report the full distribution and chronological holdout, not a few crash examples. Uncertain settlement, unavailable funding or poor exit liquidity is a valid reason to skip even an apparently correct bearish view. In a professional process, not expressing a view is also a decision.

Hypothetical worked example

Fictional 110/100 puts

Buy the 110 put for 12 and sell the 100 put for 7, so debit D is 5 and width is 10. At expiry S = 115 gives −5 per unit; S = 108 gives −3; S = 105 gives 0; S = 102 gives +3; S = 95 gives +5. With an illustrative 50-unit lot, gross maximum expiry profit is ₹250 and gross maximum expiry loss is ₹250.

Add ₹20 round-trip costs for the whole lot: net maximum gain is ₹230 and net worst matching expiry outcome is −₹270. A rebound can produce that loss even if the initial breakdown looked convincing. The worked values are fictional and do not identify a current underlying or exchange lot size.

Common mistakes

Using an expiry payoff table as a pre-expiry valuation.
Reporting the payoff without contract-unit and cost assumptions.
Calling a directional opinion a validated strategy.

Check your understanding

When does the lower-strike maximum-profit zone describe the bear put spread’s terminal payoff?

Make this chapter useful

Can you defend the reasoning?

Before moving on, answer the self-check in your own words and write why each alternative fails. Use the worked example to test that explanation. Then apply it in the module research task; keep the assumptions and the evidence that could change your answer.

Sources and further reading

Further-reading references from the curriculum source list. Contract sizes, expiry calendars, settlement references, margin parameters and tax treatment can change; verify the current operative documents for the actual product. Worked figures are illustrative, not current quotes.

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General financial education. No securities recommendation, assured outcome or personal advice. Read the risk disclosures.