The Butterfly Spread

Introduction

Most option strategies express a view on direction — up or down. The butterfly expresses a view on place: it profits when the underlying finishes near a specific central price and loses, in a strictly limited way, if it drifts too far in either direction. It is the classic pinning trade — cheap to open, defined in risk, and paying its best when the market goes quiet and settles right where you guessed.

The butterfly is also a family. The same tent-shaped payoff can be built from calls, from puts, or from a mix (the iron butterfly), and it can be deliberately skewed (the broken-wing butterfly). This lesson builds each one, shows the shared payoff, works the numbers, and points you to the Options Lab, where every version here can be set up on a real chart and revealed against history.

Quick Definition

A butterfly spread is a defined-risk strategy using three equally spaced strikes in a 1–2–1 ratio — long one, short two in the middle, long one — that profits when the underlying finishes near the middle strike at expiration.

The two short middle options are the engine of the trade; the two long outer options (the wings) cap the risk so the loss can never run away.

Building The Long Call Butterfly

Take a stock at £100 and pick three strikes: £95, £100 and £105. A long call butterfly is:

• Buy one £95 call (lower wing)
• Sell two £100 calls (the body)
• Buy one £105 call (upper wing)

You pay a small net debit — say £1.50 (£150 for the contract). That debit is the entire risk. The position profits most if the stock finishes at exactly £100, where the £95 call is worth £5, the two £100 calls expire worthless, and the £105 call expires worthless — a £5 value against a £1.50 cost, for £3.50 of profit per share.

The long put butterfly is the mirror image, built entirely from puts (buy £105 put, sell two £100 puts, buy £95 put) for the same tent-shaped result. Which you choose is usually a matter of liquidity and whether you prefer to work with calls or puts; the payoff is the same.

The Payoff: A Tent

Three numbers describe it:

• Maximum profit = the distance between adjacent strikes − the net debit, earned only if price finishes at the middle strike (£5 − £1.50 = £3.50 per share here).
• Maximum loss = the net debit (£1.50), suffered if price finishes beyond either outer strike.
• Two break-evens, one on each side of the middle strike, a debit's width in from the wings.

The Iron Butterfly: The Credit Cousin

The iron butterfly reaches the same tent a different way — and collects a credit to do it. Instead of calls only, you sell the body as a short straddle and buy the wings as protection:

• Sell one £100 call and one £100 put (the at-the-money body)
• Buy one £105 call and one £95 put (the wings)

You receive a net credit up front (say £3.50). You keep the most if price pins £100, where all four legs settle so that you retain the bulk of the credit; the long wings cap the loss if price runs away. It is the mirror of an iron condor with the two short strikes collapsed to the same central price — a sharper, higher-paying, narrower version of the same "stay near here" bet.

The practical difference from the call butterfly is mostly debit-versus-credit and how margin and assignment are handled; the shape of the bet — profit if price pins the centre, defined risk either side — is identical.

The Broken-Wing Butterfly: Skewing The Risk

A standard butterfly is symmetric. A broken-wing butterfly deliberately makes one wing wider than the other — for example £95 / £100 / £110 instead of £95 / £100 / £105. That asymmetry does two useful things:

• It reduces the cost, often turning the debit into a small credit.
• It shifts the risk to one side, so the trade can be built to have no loss at all on the near-wing side, at the cost of larger risk on the wide-wing side.

Traders use it to lean a pinning trade gently in one direction, or to open a butterfly for free in exchange for accepting more risk if the market moves strongly the "wrong" way. The payoff is no longer a neat tent — one side of the roof is longer than the other — so it demands a clear view of which direction is the safer one to be wrong about.

When A Butterfly Makes Sense — And When It Doesn't

A butterfly suits a specific, low-volatility view: you expect the underlying to sit near a particular price into expiration, and you want a cheap, defined-risk way to be paid if you are right. It shines when implied volatility is elevated (the short body is richly priced) and you expect calm.

It is the wrong tool when you have a strong directional view (a vertical spread or single option fits better), when you expect a large move (a straddle or reverse iron condor is the trade), or when you need a high probability of profit — the butterfly's full payoff sits in a narrow band, so its odds of the maximum outcome are low. It rewards precision, not conviction about direction.

Risks & Considerations

• The profit zone is narrow. Full profit requires price to finish near the middle strike; a modest miss sharply reduces the payoff.
• Defined but real loss. The debit (or the wing width minus the credit) is capped, but it is a genuine loss if price drifts beyond a wing.
• Multi-leg execution. Four legs mean more commission and more exposure to bid-ask spreads; open the whole structure as one order, not leg by leg.
• Pin risk and early assignment can complicate the short body near expiration, especially for the iron butterfly.
• Broken-wing asymmetry concentrates risk on one side — know which side that is before you open it.

Common Misconceptions

• "A butterfly is almost risk-free because it's cheap." It is defined-risk, but the whole debit can be lost, and that outcome is more likely than the maximum profit.
• "The iron butterfly is safer than the call butterfly." They are the same bet in different clothing; neither is inherently safer.
• "A broken-wing butterfly opened for a credit is free money." The credit is compensation for taking more risk on the wide-wing side.
• "Butterflies are directional." A standard butterfly is a bet on place, not direction — you want the market to sit still near the centre.

Real-World Application

A trader expects a £100 stock to drift sideways into expiration after a busy earnings season, with implied volatility elevated. Rather than sell a naked straddle (undefined risk), they open a £95 / £100 / £105 long call butterfly for a £1.50 debit — risking £150 to make up to £350 if the stock pins £100. Three weeks later the stock has barely moved, closing at £101; the butterfly is worth around £4, a healthy gain on a tiny, fully-defined stake. Had the stock instead broken out to £115, the trade would have lost only its £150 debit — a known, survivable cost. To feel this before risking capital, the same butterfly can be built in the Options Lab: pick the strikes, see the tent-shaped payoff, then look ahead on real history to watch how it would have resolved. That rehearsal — construction, payoff, outcome — is exactly how a precision strategy like the butterfly should be learned.

Key Takeaways

• A butterfly is a defined-risk, 1–2–1 three-strike strategy that profits when price finishes near the middle strike — a bet on place, not direction.
• Max profit = strike width − net debit (at the centre); max loss = the net debit (beyond a wing); with a break-even on each side.
• The iron butterfly reaches the same tent for a credit (short ATM straddle body + protective wings); the broken-wing butterfly skews one wing to cut cost and shift risk.
• Butterflies suit calm, precise views and elevated volatility; they are poor tools for strong directional or high-probability needs.
• Every version can be built and revealed on real history in the Options Lab — the ideal way to rehearse a narrow-zone strategy.