Iron Butterfly

What it is and when to use it

The iron butterfly sells the at-the-money straddle and buys a wider strangle to cap the loss. The two short legs share a strike, which is what distinguishes it from the iron condor, and because at-the-money options are the most expensive on the chain the credit is enormous: $1,481 against $285 for a 10-point condor.

That credit has an exact price. The profit band runs from 565.19 to 594.81 — 29.62 points, 5.1% of price — against the condor’s 60.70 points. And you only collect the maximum if SPY finishes pinned at 580, which almost never happens. In practice the butterfly is a bet that price stays VERY close to where it is, not simply that it does not explode.

You use it with implied volatility high and an expectation that it falls, like the condor, but with an added conviction about the level. If you have a reason to think SPY gravitates around 580 — a strong technical level, a concentration of open interest, an established range — the butterfly pays far better than the condor for the same thesis.

How it is built

• Sell 1 call at the strike closest to the current price.
• Sell 1 put at the SAME strike.
• Buy 1 call above — the upside wing.
• Buy 1 put below — the downside wing, at the same distance.

Both wings must sit the same distance from the centre. If they do not, the structure is a broken wing butterfly: a legitimate variant, but with a different profile and a directional bias worth taking on purpose rather than by mistyping a strike.

A full worked example

SPY at 580.00, 45 days to expiry. Centre at 580 and wings 20 points out, with the same model conditions as the other pages.

Net credit = 14.81 × 100 = $1,481, with $519 of maximum risk.

Look at the ratio: $519 risked to make up to $1,481, nearly 1 to 3 in your favour. It is the exact reverse of the iron condor, which risks $715 to make $285. The butterfly trades a narrow band for a far better ratio, which is why you need to be right far less often: break-even sits at 26% of the time.

Maximum profit, maximum loss and break-evens

The band is 29.62 points, 5.1% of price. Against the condor: half the width, five times the credit and a third of the risk. Which suits depends only on confidence in the level.

• Maximum profit = net credit = $1,481, only with price exactly at 580 at expiry.
• Maximum loss = (wing width − credit) × 100 = (20 − 14.81) × 100 = $519, at 560 or below and 600 or above.
• Downside break-even = centre strike − credit = 580 − 14.81 = 565.19.
• Upside break-even = centre strike + credit = 580 + 14.81 = 594.81.

The maximum profit is almost theoretical. What you actually collect is what the position is worth when you close it, and with price ten points off centre the butterfly already gives back a sizeable chunk of the credit. Management here is not optional: it is where the result lives.

The position Greeks

Theta and vega are practically identical to a 10-point iron condor’s, and yet the maximum risk is $519 against $715. The butterfly is more capital-efficient for the simple reason that it sells where there is more premium to collect.

Management: when to close, when to roll

Target 25-35% of the credit

Unlike the condor, you do not aim for 50% here: the credit is so large relative to the risk that capturing a quarter is already good business. Closing with $400 of profit on $519 of risk is an excellent trade that plenty of people dismiss for not having reached half.

Get out at 21 days

Same as the condor, and for the same reason: negative gamma concentrates at the centre and grows relentlessly in the final weeks. Here it is worse, because the short legs are at the money.

If price drifts away

With price at a break-even, the butterfly is worth roughly what you sold it for and the trade is flat. That is the moment to decide, not to wait: beyond it there is only the loss stretch.

Recentring the butterfly

Rolling the centre to the new price closes the previous trade with its result and opens another. It is legitimate, but it should be counted as two trades and not as "an adjustment", because the first one’s loss is real.

Common mistakes

Waiting to collect the maximum

It requires price to finish pinned at 580 on expiry day. The odds of that are close to nil, and chasing it means holding the position through the highest-gamma stretch of its life.

Choosing it purely for the credit

$1,481 against $285 looks like an obvious decision until you look at the bands: 29.62 points against 60.70. The credit is not the result; it is the premium on a more demanding bet.

Asymmetric wings by accident

Putting the call wing 20 points out and the put wing 15 creates a bearish bias and a different maximum loss on each side. It can be deliberate — that is a broken wing — but it almost never is.

Opening it with implied volatility low

The same mistake as in the condor, made worse: at-the-money options carry the most vega, so a short-vega position opened with volatility at lows is as exposed as it gets to a rise.