The bull put spread is a popular options strategy for traders with a moderately bullish outlook who want to collect premium while keeping risk strictly defined. As a vertical credit spread, it generates income upfront and profits when the underlying stock stays above a chosen price level. This guide covers how the bull put spread works, its payoff formulas, a real-number example, and when the strategy makes sense in your options trading toolkit.

What Is a Bull Put Spread?

Key Concept

A bull put spread is a vertical credit spread created by selling a higher-strike put option and simultaneously buying a lower-strike put option on the same underlying with the same expiration date. The net credit received at entry is the maximum profit. Also called a short put spread or put credit spread.

Think of a bull put spread as selling insurance with a cap on your liability. By selling the higher-strike put, you collect premium — similar to an insurance company collecting a policy payment. By buying the lower-strike put, you limit the payout you could owe if the “claim” (stock decline) is large. The difference between the two strikes defines your maximum exposure.

The strategy profits when the underlying stock stays above the short put strike at expiration, allowing both options to expire worthless and letting you keep the entire credit. It is fundamentally a neutral-to-bullish strategy with defined risk on both sides.

How a Bull Put Spread Works

Setting up a bull put spread involves two simultaneous transactions:

  1. Sell a higher-strike put — typically at-the-money or slightly out-of-the-money. This leg generates the bulk of the premium.
  2. Buy a lower-strike put — further out-of-the-money on the same underlying and expiration. This leg costs premium but caps your downside.

The difference between the premium received and the premium paid is your net credit — the cash deposited into your account at entry. This credit is yours to keep as long as the stock remains above the short put strike through expiration.

The combined position carries a small positive delta, meaning it benefits from the stock moving higher or staying flat. Crucially, time decay (theta) works in your favor — as each day passes, the options you sold lose value faster than the option you bought, bringing the spread closer to its maximum profit.

Strike and Expiration Selection

Most traders sell the short put at a delta between 0.25 and 0.40, which corresponds to a 60-75% probability of the stock finishing above that strike. For expiration, 30-45 days to expiration (DTE) offers a good balance — enough time to collect meaningful premium while benefiting from accelerating theta decay in the final weeks. Placing the short strike near a known support level adds a technical edge to the probability math.

Pro Tip

Consider closing the spread early when it reaches 50-80% of maximum profit. For example, if you collected $3.50 in credit, look to buy the spread back for $0.70-$1.75. This locks in most of the gain while eliminating the risk of a late reversal or pin risk near expiration.

Video: Bull Put Spread Strategy Explained

Bull Put Spread Payoff Diagram

The payoff profile of a bull put spread at expiration is defined by three formulas. Note that these values assume the position is held to expiration — before expiration, the spread’s market value is also affected by implied volatility and remaining time value.

Maximum Profit
Max Profit = Net Premium Received
The most you can earn is the credit collected when opening the spread. Achieved when the stock is at or above the short put strike at expiration and both puts expire worthless.
Maximum Loss
Max Loss = (Higher Strike – Lower Strike) – Net Premium Received
The most you can lose is the width of the spread minus the credit received. Occurs when the stock is at or below the long put strike at expiration.
Breakeven Price
Breakeven = Higher Strike – Net Premium Received
The stock price at which the spread breaks even at expiration. Below this price, the position loses money.

The payoff shape has three zones: above the short put strike, profit is flat at the maximum (net credit). Between the two strikes, profit decreases linearly as the stock falls. Below the long put strike, the loss is flat at the maximum. This creates a defined-risk, defined-reward profile — you always know your worst case before entering the trade.

Bull Put Spread Example

SPY Bull Put Spread at Expiration

Setup: SPY is trading at $448. You sell 1 SPY $445 put at $6.00 per share and buy 1 SPY $435 put at $2.50 per share, both expiring in 35 days.

Net credit = $6.00 – $2.50 = $3.50 per share ($350 per contract)

Key levels:

  • Max Profit = $3.50 per share = $350 per contract
  • Max Loss = ($445 – $435) – $3.50 = $6.50 per share = $650 per contract
  • Breakeven = $445 – $3.50 = $441.50
Scenario SPY Price Short $445 Put Long $435 Put Net P&L
Stock above short strike $450 Expires worthless Expires worthless +$350
Stock between strikes $440 ITM — you owe $5.00/share Expires worthless -$150
Stock below both strikes $430 ITM — you owe $15.00/share ITM — you receive $5.00/share -$650

At $440, the short $445 put is in the money by $5.00. After subtracting from the $3.50 credit: $3.50 – $5.00 = -$1.50 per share (-$150). At $430, the short put costs $15.00 but the long put recovers $5.00, netting $3.50 – $15.00 + $5.00 = -$6.50 per share (-$650) — the maximum loss. No matter how far SPY falls below $435, the loss stays capped at $650 per contract.

Bull Put Spread vs Bull Call Spread

The bull put spread and the bull call spread are both moderately bullish strategies with defined risk, but they use different option types and have opposite cash flow profiles at entry.

Bull Put Spread

  • Credit spread — collect premium upfront
  • Uses put options (sell higher strike, buy lower strike)
  • Time decay helps — theta works in your favor
  • Max profit = net credit received
  • Profits if stock stays above short put strike

Bull Call Spread

  • Debit spread — pay premium upfront
  • Uses call options (buy lower strike, sell higher strike)
  • Time decay hurts — theta works against you
  • Max profit = spread width minus debit paid
  • Profits if stock rises above breakeven price

Both strategies have similar risk-reward profiles at the same strikes and expiration. The bull put spread is preferred when you want to collect income and let time decay work in your favor — you profit by the stock simply not falling. The bull call spread is preferred when you have stronger directional conviction and want the stock to actively move higher.

When to Use a Bull Put Spread

A bull put spread works best in specific market conditions:

  • Moderately bullish outlook: You expect the stock to hold above a support level or drift higher, but don’t anticipate a large rally
  • Income generation with defined risk: You want to collect premium without the substantial downside risk of a naked short put
  • Time decay advantage: You want theta working in your favor — each passing day brings the spread closer to full profit
  • Identified support level: Place the short put strike at or below a technical support level where the stock has historically held
Pro Tip

Avoid opening bull put spreads just before earnings announcements or major economic events. A gap down through both strikes can result in an immediate maximum loss. If you want to trade around events, wait until after the announcement or use a narrower spread to limit exposure. Explore more strategies in our Options Trading Strategies course.

Common Mistakes

1. Selling puts too close to the current price. An at-the-money short put has roughly a 50% chance of finishing in the money (approximated by its delta). Moving the short strike 5-10% out of the money reduces the credit collected but significantly improves the probability of keeping the full premium. Balance premium size against probability of success.

2. Ignoring account-level stress during sharp selloffs. While the spread’s at-expiration max loss is always defined by the spread width minus credit, a rapid market decline can increase your broker’s margin requirements on other positions and reduce your overall account equity. If your account holds multiple spreads or other positions, the combined drawdown may trigger a margin call — even though each individual spread has defined risk. Size your total exposure conservatively.

3. Using too wide a spread without adjusting position size. A wider spread collects more premium but exposes you to a larger maximum loss. A $20-wide SPY spread might collect $7.00 in credit but risks $13.00 per share. Always size the spread width relative to your account — the credit received should represent a reasonable return on the capital at risk, not just the largest number you can collect.

4. Holding through expiration without a plan for assignment. If the stock finishes between the two strikes at expiration, your short put may be assigned while your long put expires worthless. This forces you to buy 100 shares at the short strike, tying up significant capital. Have a clear exit plan — most traders close spreads before expiration day to avoid pin risk and unexpected assignment.

Risks and Limitations

Important Limitation

A bull put spread has an asymmetric risk profile — your maximum loss is typically larger than your maximum profit. In the SPY example, the max loss ($650) is nearly twice the max profit ($350). This means you need a high win rate for the strategy to be profitable over time, which is why strike selection and probability analysis are critical.

Profit is capped at the credit received. Even if SPY rallies sharply above the short put strike, your profit is limited to the $350 credit. You do not participate in any upside beyond keeping the premium.

Early assignment risk. American-style put options can be assigned at any time. Assignment is most likely when the short put is deep in the money with little extrinsic value remaining. If assigned, you are obligated to buy 100 shares at the short put strike. You still hold the long put, which you can exercise or sell for protection — but the outcome depends on the stock price and remaining time value, not necessarily the full maximum loss. Monitor the short put’s extrinsic value and consider closing early if it approaches zero.

Margin is required. Your broker will hold margin equal to the spread width minus the credit received — the maximum loss amount. For a $10-wide spread with $3.50 credit, the margin requirement is $650 per contract. This capital is locked until the spread is closed or expires. If your outlook turns bearish, consider a bear put spread or a bull call spread for a different risk profile.

Not ideal for strongly bullish views. If you expect a large rally, the bull put spread’s capped profit makes it an inefficient use of capital compared to a long call or bull call spread, which can capture more upside.

Frequently Asked Questions

A cash-secured put involves selling a single put option and holding enough cash to buy 100 shares if assigned — your risk is the full strike price minus the premium received. A bull put spread adds a long put below the short put, capping the maximum loss to the spread width minus the credit. The bull put spread requires significantly less capital (margin is based on the spread width, not the full assignment value) and has strictly defined risk. The tradeoff is that the bull put spread collects less premium than a standalone cash-secured put at the same strike.

Time decay (theta) works in the bull put spread seller’s favor. Because you are a net seller of options — the short put has more theta than the long put — the passage of time reduces the value of the spread. As expiration approaches, if the stock remains above the short put strike, both options lose value and the spread converges toward zero. This allows you to keep the full credit or buy the spread back for a small amount to close early. Theta acceleration is strongest in the final 30 days before expiration, which is why many traders open these spreads with 30-45 DTE.

American-style put options can be assigned at any time, though early assignment is most likely when the short put is deep in the money with little extrinsic value remaining. If assigned, you are obligated to buy 100 shares at the short put strike price. You still hold the long put, which you can exercise to sell the shares at the lower strike or sell on the open market. The realized loss depends on the stock price at the time and any remaining time value in the long put — it is not automatically the maximum loss. To reduce early assignment risk, monitor the short put’s extrinsic value and consider closing the spread if it drops near zero.

Spread width — the difference between the two strike prices — determines both your maximum loss and the premium collected. Narrower spreads (e.g., $5 wide) have a lower maximum loss but collect less premium. Wider spreads (e.g., $10-$20 wide) collect more credit but carry a higher maximum loss. A common guideline is to target a credit of at least one-third of the spread width, giving a roughly 2:1 risk-to-reward ratio. Also consider liquidity — stick to strikes with strong open interest and tight bid-ask spreads to minimize execution costs.

Disclaimer

This article is for educational and informational purposes only and does not constitute investment advice. Options involve risk and are not suitable for all investors. The examples use hypothetical scenarios for illustration; actual results will vary based on market conditions, commissions, and other factors. Consult a qualified financial advisor before trading options.