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Bear Put Spread: Debit, Breakeven, Capped Downside Gain, and Assignment

For educational purposes only; not investment advice.

Direct answer

Section titled “Direct answer”

A bear put spread, also called a put debit spread, buys a put at a higher strike and sells a put at a lower strike with the same underlying, expiration, exercise style, settlement, multiplier, and quantity. It is generally opened for a net debit and expresses a view that the underlying will decline toward or below the short-put strike by expiration.

Maximum contractual loss is the initial net debit. Maximum expiration profit is strike width − net debit, multiplied by the contract multiplier. Selling the lower-strike put reduces cost but gives up further payoff below that strike.

Expiration payoff and changing Greeks

Section titled “Expiration payoff and changing Greeks”

Let the long-put strike be K_H, short-put strike K_L, with K_H > K_L, and net debit D. Profit per underlying unit at expiration is:

max(K_H − S_T, 0) − max(K_L − S_T, 0) − D

  • If S_T ≥ K_H, both puts expire without intrinsic value and loss is D.
  • If K_L < S_T < K_H, profit rises dollar for dollar as spot falls.
  • If S_T ≤ K_L, spread value is capped at K_H − K_L, so maximum profit is (K_H − K_L) − D.
  • Expiration breakeven is K_H − D before fees.

Before expiration, the spread generally has negative delta and positive gamma. Its theta and vega depend on spot, time, and the relative implied volatilities of both strikes. Equity put skew often makes the lower-strike short put relatively expensive, reducing debit, but a changing skew can move the spread even if headline volatility is unchanged.

The spread is not simply a cheaper long put. A long put preserves additional payoff as spot approaches zero; the bear put spread stops gaining below K_L. The correct comparison uses the same expiration and executable prices, then tests whether the forgone tail payoff is worth the premium saved.

American-style short puts can be assigned early, especially when deep in the money with little extrinsic value. Early assignment creates long shares at K_L; the higher-strike long put remains a separate contract. That position may still be economically hedged, but it creates stock funding, margin, exercise, and gap decisions that do not appear on a static expiration graph.

100/90 put spread example

Section titled “100/90 put spread example”

Suppose the underlying is $100. One 100 put is bought and one 90 put is sold for the same expiration, for a $3.00 net debit and 100-share multiplier.

  • Maximum loss: $3.00 × 100 = $300.
  • Strike width: $100 − $90 = $10.
  • Maximum profit: ($10 − $3) × 100 = $700.
  • Expiration breakeven: $100 − $3 = $97.

At a $105 expiration price, both puts have no intrinsic value and loss is $300. At $95, the long put is worth $5 and the short put zero, so profit is ($5 − $3) × 100 = $200. At $85, the long put is worth $15 and the short put $5; the $10 spread value produces maximum profit of $700.

Maximum reward relative to debit is $700 / $300 ≈ 233.3%, but this is not a probability or expected return. If the spread can be sold before expiration for $7.50, profit before fees is ($7.50 − $3.00) × 100 = $450. Waiting for the final $250 exposes the position to reversal, execution, and expiration risk.

Trade and expiration checklist

Section titled “Trade and expiration checklist”
  • Verify that both legs match in underlying, expiration, exercise style, settlement, multiplier, and quantity.
  • Use the executable complex-order market to calculate debit; favorable leg midpoints may never trade together.
  • Convert debit, maximum profit, fees, and stress paths into account dollars.
  • Compare the spread with the outright long put, including the tail payoff surrendered below K_L.
  • Inspect liquidity and volatility skew at both strikes; a narrow-looking net midpoint can hide two wide markets.
  • Stress a slow decline, sharp decline, no move, rebound, volatility crush, skew flattening, and widening spreads.
  • Monitor the short put’s extrinsic value and early-assignment risk when it becomes deep in the money.
  • If assigned, separately evaluate long shares, the long put, dividends, financing, and broker requirements.
  • Near expiration, plan for pin risk: spot around either strike can leave one leg exercised and the other expired.
  • Treat a roll as closing the original spread and opening a new trade; preserve the realized economics.

Closing the spread as a combination often reduces legging risk. Exercising the long put merely to obtain its intrinsic value may surrender time value and create stock transactions. Compare the executable spread close with exercise and assignment outcomes before acting.

Common misconceptions

Section titled “Common misconceptions”
  • “A bear put spread has unlimited downside profit.” Gain stops below the short-put strike.
  • “The short put is free financing.” It lowers debit by selling the most severe downside payoff.
  • “Maximum loss means the position cannot create other account demands.” Early assignment can create 100 long shares per standard contract.
  • “A volatility increase always helps.” Relative skew and each leg’s vega determine the net effect.
  • “A bearish forecast is enough.” The move must be large enough and timely enough to overcome debit and execution costs.
  • “A 233.3% maximum return is an expected return.” It is one endpoint divided by debit, with no probability weighting.
  • “Rolling turns a losing spread into a winner.” It changes expiration or strikes by closing one position and opening another.
Section titled “Related topics”

Authoritative sources

Section titled “Authoritative sources”