Butterfly Spread: Strategy, Payoff & When to Use It in 2026

What Is a Butterfly Spread?

A butterfly spread is a three-legged options strategy built around three strike prices that profits when the underlying asset finishes near the middle strike at expiry. It combines a bull spread and a bear spread into a single position with limited risk and limited profit potential, making it one of the most capital-efficient ways to bet on low volatility.

The structure uses four option contracts across three equally spaced strikes. You buy one contract at the lowest strike, sell two contracts at the middle strike, and buy one contract at the highest strike - all sharing the same expiry date. The result is a position that earns its maximum profit if the underlying price lands exactly at the middle strike and loses no more than the initial premium paid.

Butterfly spreads are popular among traders who expect a stock or index to stay within a tight range. Unlike a naked short straddle - which also profits from low volatility but carries theoretically unlimited risk - the butterfly caps your downside at the net premium you pay to enter the trade. This makes it attractive for defined-risk strategies in 2026, particularly around events where a trader has a strong view on where the price will settle but wants to avoid open-ended exposure.

The name comes from the payoff diagram. When you plot profit and loss against the underlying price at expiry, the shape has a peaked centre and two flat wings - resembling a butterfly. The peak sits at the middle strike, and the wings extend to the lower and upper strikes where the position breaks even before flattening into maximum loss territory.

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How Does a Butterfly Spread Work?

A long call butterfly spread works by buying one in-the-money call, selling two at-the-money calls, and buying one out-of-the-money call - all at equally spaced strikes and the same expiry. The net cost to enter the trade is small because the premium collected from selling two calls partially offsets the cost of buying the outer calls.

Let's walk through a concrete butterfly spread example. Suppose a stock is trading at £100 and you expect it to stay close to that price over the next 30 days. You could construct a long call butterfly as follows:

• Buy 1 call at the £95 strike (lower wing) for £7.20
• Sell 2 calls at the £100 strike (body) for £4.00 each (£8.00 total collected)
• Buy 1 call at the £105 strike (upper wing) for £2.00

The net debit is: £7.20 - £8.00 + £2.00 = £1.20

This £1.20 is your maximum possible loss. It occurs if the stock finishes below £95 or above £105 at expiry - in either case, all options expire worthless or cancel out to zero value.

The maximum profit occurs when the stock finishes exactly at £100 (the middle strike). At that point, the £95 call is worth £5.00 intrinsic value, the two short £100 calls expire worthless, and the £105 call also expires worthless. Your profit is £5.00 - £1.20 = £3.80 per share. That's a return of over 300% on the premium invested.

The equal spacing between strikes is critical. In this example, each strike is £5 apart. This symmetry is what gives the butterfly its characteristic shape and ensures the payoff is balanced around the centre. The distance between strikes is called the wing width, and it determines both the maximum profit and the range within which the trade is profitable.

Two breakeven points exist:

• Lower breakeven = lower strike + net debit = £95 + £1.20 = £96.20
• Upper breakeven = upper strike - net debit = £105 - £1.20 = £103.80

The stock needs to finish between £96.20 and £103.80 for the trade to be profitable. This gives you a £7.60 profitable range on a £1.20 investment - a favourable risk-reward structure for range-bound scenarios.

For a deeper look at how option positions interact, see our guide to derivatives fundamentals.

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Butterfly Spread Payoff

The butterfly spread payoff is zero outside the wing strikes, rises linearly from the lower breakeven to a peak at the middle strike, and then falls linearly back to zero at the upper breakeven. Maximum profit equals the wing width minus the net premium paid, and maximum loss is limited to the net premium.

Here's a payoff table for the long call butterfly example above (strikes at £95, £100, £105 with a £1.20 net debit), showing the profit or loss at various stock prices at expiry:

The payoff diagram forms a triangle: flat at -£1.20 outside the wings, rising to +£3.80 at the centre, then falling back to -£1.20. This triangular shape is the defining visual feature of a butterfly spread.

Formally, the payoff at expiry for a long call butterfly with strikes ( K_1 < K_2 < K_3 ) where ( K_2 = (K_1 + K_3) / 2 ) is:

[ \text{Payoff} = \max(S_T - K_1, 0) - 2 \cdot \max(S_T - K_2, 0) + \max(S_T - K_3, 0) ]

And the profit is:

[ \text{Profit} = \text{Payoff} - \text{Net Debit} ]

The maximum payoff of ( K_2 - K_1 ) occurs at ( S_T = K_2 ). Outside the range ([K_1, K_3]), the payoff is exactly zero, and the trade's loss equals the premium paid.

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Butterfly Spread in Python

You can model the butterfly spread payoff across a range of stock prices with a short Python script. This is useful for visualising how different strike selections and premium levels affect the profit profile.

import numpy as np
import matplotlib.pyplot as plt


def butterfly_payoff(S_T, K1, K2, K3, net_debit):
    """Calculate profit/loss for a long call butterfly spread."""
    long_lower = np.maximum(S_T - K1, 0)
    short_middle = -2 * np.maximum(S_T - K2, 0)
    long_upper = np.maximum(S_T - K3, 0)
    payoff = long_lower + short_middle + long_upper
    return payoff - net_debit


# --- Trade parameters ---
K1 = 95     # lower strike (buy 1 call)
K2 = 100    # middle strike (sell 2 calls)
K3 = 105    # upper strike (buy 1 call)
net_debit = 1.20

# --- Generate payoffs across a range of prices ---
stock_prices = np.linspace(85, 115, 500)
profits = butterfly_payoff(stock_prices, K1, K2, K3, net_debit)

# --- Key levels ---
max_profit = (K2 - K1) - net_debit
lower_breakeven = K1 + net_debit
upper_breakeven = K3 - net_debit

print(f"Max profit:       {max_profit:.2f}")
print(f"Max loss:         {net_debit:.2f}")
print(f"Lower breakeven:  {lower_breakeven:.2f}")
print(f"Upper breakeven:  {upper_breakeven:.2f}")
print(f"Profit range:     {upper_breakeven - lower_breakeven:.2f} wide")

# --- Payoff table ---
check_prices = [90, 93, 95, 96.20, 97, 98, 99, 100,
                101, 102, 103, 103.80, 105, 107, 110]

print("\nStock Price | Payoff | Profit/Loss")
print("-" * 40)
for p in check_prices:
    pnl = butterfly_payoff(np.array([p]), K1, K2, K3, net_debit)[0]
    payoff = pnl + net_debit
    print(f"  {p:>7.2f}   | {payoff:>6.2f} |  {pnl:>+7.2f}")

# --- Plot ---
fig, ax = plt.subplots(figsize=(10, 6))
ax.plot(stock_prices, profits, color="#2563eb", linewidth=2)
ax.axhline(y=0, color="grey", linestyle="-", alpha=0.3)
ax.fill_between(stock_prices, profits, 0,
                where=(profits > 0), alpha=0.15, color="#2563eb")

ax.axvline(x=K1, color="#ef4444", linestyle="--", alpha=0.5, label=f"K1 = {K1}")
ax.axvline(x=K2, color="#22c55e", linestyle="--", alpha=0.5, label=f"K2 = {K2}")
ax.axvline(x=K3, color="#ef4444", linestyle="--", alpha=0.5, label=f"K3 = {K3}")

ax.set_xlabel("Stock Price at Expiry", fontsize=12)
ax.set_ylabel("Profit / Loss", fontsize=12)
ax.set_title("Long Call Butterfly Spread Payoff", fontsize=14)
ax.legend(fontsize=11)
ax.grid(True, alpha=0.3)
plt.tight_layout()
plt.savefig("butterfly_spread_payoff.png", dpi=150)
plt.show()

The script produces the characteristic triangular payoff shape. You can adjust the strike width by changing ( K_1 ), ( K_2 ), and ( K_3 ) - wider wings increase maximum profit but require the stock to finish closer to the centre for the trade to work. The butterfly_payoff function is vectorised with NumPy, so it handles arrays of prices efficiently.

Try modifying the parameters to see how the trade behaves with different strike spacings or net debits. For more on building financial models in Python, see our Python for quant finance guide.

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Types of Butterfly Spreads

There are four main types of butterfly spread: the long call butterfly, long put butterfly, iron butterfly, and broken wing butterfly. Each uses a different combination of options but produces a similar payoff profile centred on the middle strike.

Long Call Butterfly

This is the standard version described above. You buy one lower-strike call, sell two middle-strike calls, and buy one upper-strike call. It's entered for a net debit and profits when the stock stays near the middle strike. The long call butterfly is the most common type and the one most traders think of when they hear "butterfly spread."

Long Put Butterfly

The put version works identically in terms of payoff at expiry. You buy one lower-strike put, sell two middle-strike puts, and buy one upper-strike put. At expiry, put-call parity guarantees the same profit profile as the call butterfly (assuming the same strikes and expiry). In practice, traders sometimes prefer the put butterfly when the lower-strike options have better liquidity or tighter spreads. The choice between call and put butterflies is often driven by execution costs rather than theoretical differences.

Iron Butterfly

The iron butterfly combines puts and calls. You sell one ATM put and one ATM call (creating a short straddle at the middle strike), then buy one OTM put at a lower strike and one OTM call at a higher strike for protection. Unlike the long call or put butterfly, the iron butterfly is entered for a net credit.

The structure looks like this:

• Buy 1 put at the lower strike
• Sell 1 put at the middle strike
• Sell 1 call at the middle strike
• Buy 1 call at the upper strike

Maximum profit equals the net credit received, which occurs when the stock finishes exactly at the middle strike. Maximum loss equals the wing width minus the credit received. The iron butterfly is functionally equivalent to a long butterfly - it's just constructed differently and entered as a credit rather than a debit.

Many traders prefer the iron butterfly because it collects premium upfront and can be easier to manage from a margin perspective. It's especially popular in index options trading in 2026 where the ATM straddle carries significant premium.

Broken Wing Butterfly

A broken wing butterfly (sometimes called a skip-strike butterfly) uses unequal spacing between the strikes. For example, you might set the strikes at £95, £100, and £110 instead of £95, £100, and £105. This shifts the payoff diagram: the trade may be entered for a credit on one side and has an asymmetric risk profile.

Traders use broken wing butterflies to create a directional bias while still maintaining a butterfly-like structure. The wider wing reduces risk on one side at the cost of increased exposure on the other. These are more advanced trades that require careful analysis of the risk-reward trade-off.

For background on how options pricing works across these structures, see our article on option pricing models.

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When to Use a Butterfly Spread

Use a butterfly spread when you expect the underlying asset to trade within a narrow range and implied volatility is relatively high - giving you more premium to collect on the short strikes. The ideal setup is a range-bound market where you have a specific target price in mind for expiry.

Low volatility expectation. The butterfly spread is fundamentally a short volatility trade. You profit when the underlying doesn't move much. If you believe realised volatility over the option's life will be lower than what's currently priced into the market, the butterfly gives you a defined-risk way to express that view. For more on volatility dynamics, see our guide to the Greeks and volatility in options.

Range-bound markets. Stocks that have been consolidating in a tight range are classic butterfly candidates. If a stock has been trading between £95 and £105 for weeks and you expect that to continue, a butterfly centred at £100 lets you profit from that stasis.

Earnings plays. Some traders use butterflies around earnings announcements. The logic: implied volatility is typically inflated before earnings, making the short strikes valuable. If the trader believes the stock will have a muted reaction (perhaps because guidance is already well understood), the butterfly captures the post-earnings volatility crush at a low cost. The limited risk is crucial here because earnings can surprise.

Cheap directional bets. Because the butterfly costs little to enter, it can serve as a cheap way to bet on a specific price target. If you're convinced a stock will be near £110 in 30 days, you could centre a butterfly at £110 for a small debit. The risk-reward ratio is excellent if you're right, and the maximum loss is capped at the premium.

Implied volatility is high. When implied volatility is elevated, the premium collected from the two short middle-strike options is larger, which reduces the net cost of the butterfly. This improves the risk-reward ratio. Conversely, in very low implied volatility environments, butterflies become less attractive because the premium collected is thin. If you're interested in strategies that sell volatility premium, the butterfly is one of the safest ways to do it.

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The Greeks of a Butterfly Spread

A butterfly spread is approximately delta-neutral near the middle strike, has positive theta that accelerates as expiry approaches, and carries negative vega - meaning it benefits from falling implied volatility. These Greek characteristics make it behave like a short volatility position with capped risk.

Delta

At inception, a butterfly centred at-the-money has near-zero delta. The long lower call has positive delta, the two short middle calls have negative delta, and the long upper call has positive delta - they roughly cancel out. As the underlying moves away from the middle strike, delta becomes non-zero: the butterfly develops a directional bias. If the stock rises above the middle strike, the position becomes short delta (it benefits from the stock falling back). If the stock falls below the middle strike, it becomes long delta.

Gamma

Gamma is the rate of change of delta. A long butterfly has negative gamma when the underlying is near the middle strike and positive gamma near the wings. This is intuitive: around the middle strike, you don't want the stock to move (negative gamma works against you if it does), while near the wings, movement toward the centre helps you. The gamma profile flips sign as you move across the strikes.

Theta

Theta is where the butterfly earns its keep. The position has positive theta when the underlying is near the middle strike, meaning it profits from the passage of time. The two short options at the middle strike decay faster than the two long options at the wings, generating net time decay in your favour. This theta accelerates as expiry approaches - making the final week or two the most profitable period if the stock remains range-bound.

Vega

A butterfly spread has negative vega near the middle strike. This means the position loses value if implied volatility rises and gains value if it falls. This is consistent with the trade's purpose: you're betting on low movement, so a drop in implied volatility benefits you. The vega exposure is modest compared to a naked short straddle because the long wings offset much of the short vega from the middle strikes.

Understanding how these Greeks interact is essential for managing butterfly positions. For a thorough treatment of the Greeks and their behaviour, see our dedicated guide.

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Butterfly Spread vs Other Strategies

The butterfly spread sits in a family of limited-risk strategies that profit from range-bound markets. Choosing between them depends on your view on the width of the expected range, the cost you're willing to pay, and how much risk you can tolerate.

Butterfly vs iron condor. An iron condor sells an OTM put spread and an OTM call spread simultaneously. It profits across a wider range than a butterfly but offers a lower maximum profit. Think of the iron condor as the butterfly's wider, flatter cousin - it's more forgiving on direction but pays less when you're right. If you have a precise price target, the butterfly is better. If you just think the stock will stay in a broad range, the iron condor is more appropriate.

Butterfly vs short straddle. A short straddle (sell ATM call and ATM put) collects the most premium and has the highest maximum profit at the middle strike. But the risk is theoretically unlimited if the stock moves sharply. The butterfly sacrifices some profit potential in exchange for capping the downside. For most retail traders and risk-conscious professionals in 2026, the butterfly's defined risk is worth the trade-off.

Butterfly vs short strangle. A short strangle sells OTM options on both sides. It has a wider profitable range than a straddle but still carries unlimited risk. The butterfly is the defined-risk alternative: you can think of it as a straddle with insurance purchased on both sides.

The pattern is clear: the butterfly trades maximum profit potential for maximum safety. Where the straddle and strangle leave you exposed to large moves, the butterfly puts a hard floor under your losses.

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Practical Tips and Common Mistakes

Setting up a butterfly spread correctly involves more than picking three strikes. Execution quality, timing, and position management all affect whether the trade works in practice.

Choose liquid options. A butterfly involves four contracts across three strikes. If any of those strikes has wide bid-ask spreads, slippage eats into your edge. Stick to highly liquid underlyings - major indices, large-cap stocks, and popular ETFs. In 2026, weekly options on indices like the S&P 500 and FTSE 100 offer excellent liquidity for butterfly trades.

Mind the transaction costs. Four contracts mean four commissions (or more, if you trade individual legs). On a trade that costs £1.20 to enter with a maximum profit of £3.80, even £0.20 in total commissions represents a meaningful drag. Use a broker with competitive options fees and consider entering the butterfly as a single multi-leg order rather than legging in.

Watch for early assignment risk. If you're trading American-style options and your short strikes go in-the-money before expiry, you face the possibility of early assignment. This is most common with short calls on stocks approaching an ex-dividend date. Early assignment doesn't necessarily hurt you - it just changes the position into something you need to manage. European-style index options (like FTSE 100 options) eliminate this risk entirely because they can only be exercised at expiry.

Choose your strike width carefully. Narrower wings (smaller spacing between strikes) produce a cheaper butterfly with a higher percentage return if you're exactly right, but the profitable range is also narrower. Wider wings cost more but give you a larger window for profit. Match the wing width to your conviction level: use narrow wings when you have a strong, precise view on the settlement price, and wider wings when you're less certain.

Time your entry. Butterflies benefit from time decay, but they also need time for the trade to develop. Entering too early (say, 60 days before expiry) means you'll hold the position through a long period where theta is modest. Many traders prefer to enter butterflies with 15 to 30 days until expiry, when theta acceleration is beginning but there's still time for the underlying to settle into the target range.

Don't hold to expiry by default. The textbook butterfly shows maximum profit at expiry, but in practice many traders close the position before expiration. If the stock is near your middle strike and you've captured 50-70% of the maximum profit with several days still remaining, it often makes sense to close and remove the risk of a last-minute move. Pin risk - the uncertainty around whether short options expire in-the-money by a tiny amount - can cause unexpected outcomes on expiry day.

Understand the profit zone, not just max profit. Beginners sometimes focus on the maximum profit at the middle strike and forget that the trade needs the stock to finish within the breakeven range to make any money at all. Before entering, calculate your breakevens and assess whether a finish within that range is realistic given the stock's recent behaviour and upcoming catalysts.

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Frequently Asked Questions

What is the maximum loss on a butterfly spread?

The maximum loss on a butterfly spread is the net premium paid to enter the trade (for a long call or long put butterfly) or the wing width minus the credit received (for an iron butterfly). This loss occurs if the underlying finishes below the lowest strike or above the highest strike at expiry. For example, a butterfly entered for a £1.20 net debit has a maximum loss of exactly £1.20 per share, regardless of how far the stock moves. This defined-risk characteristic is one of the butterfly's main attractions compared to unlimited-risk strategies like naked straddles.

Is a butterfly spread bullish or bearish?

A standard at-the-money butterfly spread is neither bullish nor bearish - it's a neutral strategy that profits from the stock staying near the middle strike. However, you can create directional butterflies by shifting the centre strike above or below the current price. A butterfly centred at £110 on a £100 stock is a mildly bullish bet that the stock will rise to £110 by expiry. A butterfly centred at £90 is a bearish bet. The directional bias depends entirely on where you place the middle strike relative to the current price.

How does the iron butterfly differ from a regular butterfly?

The iron butterfly produces the same payoff at expiry as a long call or long put butterfly with the same strikes. The structural difference is that the iron butterfly combines puts and calls (selling an ATM straddle and buying protective wings), while a regular butterfly uses all calls or all puts. The practical difference is in how the trade is entered: an iron butterfly is entered for a net credit, while a long call or put butterfly is entered for a net debit. Many traders prefer the iron butterfly because collecting premium upfront feels more intuitive, and the margin treatment can be more favourable with some brokers. Functionally, they're equivalent trades.

When should I close a butterfly spread before expiry?

Consider closing a butterfly spread early when you've captured a significant portion of the maximum profit - typically 50% to 70% - and there's still time remaining until expiry. The reason is asymmetric risk: once you've captured most of the available profit, the remaining potential gain is small relative to the risk that the stock moves away from your target. Additionally, close early if the underlying has moved significantly away from the middle strike and the remaining value is minimal - there's little point holding a position that's already near maximum loss in the hope of a reversal. Pin risk around expiry is another reason to close early, especially with American-style options.

Can I use a butterfly spread around earnings announcements?

Yes, and it's a common application. The strategy works well when you believe implied volatility is overpriced relative to the actual move the stock will make post-earnings. Before earnings, implied volatility is typically elevated as the market prices in uncertainty. If the stock reacts less than expected, the post-earnings volatility crush benefits the butterfly's negative vega exposure. The key risk is that earnings surprises can produce large gaps that push the stock well outside the butterfly's profitable range. Because your loss is capped at the premium paid, earnings butterflies offer a defined-risk way to express a view that the market is overestimating the size of the earnings move.

How does the butterfly spread relate to the Black-Scholes model?

Under the Black-Scholes framework, a butterfly spread's fair value can be calculated by pricing each of the four option legs individually and summing them. The net theoretical value depends on the underlying price, time to expiry, risk-free rate, and implied volatility. Interestingly, a very narrow butterfly spread (with strikes close together) approximates a bet on the probability density at the middle strike - it's proportional to the second derivative of the option price with respect to strike. Quantitative researchers use butterfly quotes to extract information about the implied probability distribution. In practice, the Black-Scholes model is a starting point, but real butterfly pricing also reflects the volatility smile, skew, and term structure effects.