Iron condors and iron butterflies: building, sizing and adjusting range-bound positions

What you will learn

• How to build an iron condor from two credit spreads and compute its credit, maximum loss, break-evens and POP.
• How an iron butterfly differs and when each structure fits.
• A sizing rule based on maximum loss and account size.
• A worked adjustment: rolling the untested side and the trade-off it creates.

Explanation

An iron condor is a put credit spread below the market plus a call credit spread above it, same expiry, usually the same width. You collect both credits and profit if the underlying stays between the short strikes. Only one side can lose at expiry, so the maximum loss is capped.

• Credit = put-spread credit + call-spread credit; maximum loss = width - total credit (equal wings).
• Break-evens = short put - total credit and short call + total credit; POP approximately 1 - total credit / width.

An iron butterfly puts both short strikes at the same (usually at-the-money) strike: a short straddle with wings. It collects a much larger credit, with a narrower profit zone, a smaller maximum loss relative to width and a lower POP. Choose the condor for a wide zone with a poor credit-to-risk ratio; choose the butterfly when IV is very elevated and you accept more frequent management.

Strike selection by delta

A common construction sells the 16-delta put and call (roughly one expected move away) with wings 5 or 10 points further out; a tighter version sells 20- to 30-delta strikes. Because of put skew (lesson 2), the short put at a given delta sits further from the price in points than the short call.

Sizing

Size by maximum loss, never by credit or margin: number of condors = (account x risk per position) / maximum loss per condor, rounded down. A typical budget per defined-risk position is 1 to 3 percent of the account; lesson 11 adds a cap across all positions.

Management rules of thumb

• Take profit at about 50 percent of the credit; the second half is earned slowly and carries most of the gamma risk.
• Close or roll at around 21 DTE regardless of profit.
• When a short strike is reached, the standard defence is to roll the untested side closer for more credit, which reduces maximum loss but narrows the zone.
• Define a maximum-loss exit in advance, for example at one or two times the original credit.

Worked example

Hypothetical example: an index ETF at $100, 45 DTE, IV 25 percent, interest and dividends ignored. Expected move: 100 x 0.25 x square root(45/365) = $8.78, so about 91 to 109.

Build the condor (model mid prices, rounded): sell 91 put at 0.60, buy 86 put at 0.15 (credit 0.45); sell 109 call at 0.80, buy 114 call at 0.30 (credit 0.50). Total credit 0.95 ($95). Width 5.00. Maximum loss 5.00 - 0.95 = 4.05 ($405). Break-evens 90.05 and 109.95. POP approximately 1 - 0.95 / 5 = 81 percent. Return on risk at a full win: 95 / 405 = 23.5 percent.

Size: account $25,000, risk per position 2 percent = $500. 500 / 405 = 1.23, so one condor. A $10,000 account could not fit even one at this budget, which is itself a warning.

Iron butterfly for comparison: sell the 100 put at 3.50 and the 100 call at 3.50, buy the 95 put at 1.50 and the 105 call at 1.65. Credit 7.00 - 3.15 = 3.85. Maximum loss 5.00 - 3.85 = 1.15 ($115). Break-evens 96.15 and 103.85. POP approximately 1 - 3.85 / 5 = 23 percent if held to expiry; in practice butterflies are closed early at a fraction of the credit.

Adjustment at 21 DTE: the ETF has risen to $107 and the short 109 call is tested. Model prices: 109 call 1.71, 114 call 0.49 (call spread worth 1.22, a loss of 0.72); the 91/86 put spread is worth about 0.01. Options:

1. Close everything: pay about 1.23 against 0.95 received: loss 0.28 ($28) plus costs. Small and clean.
2. Roll the put spread up: buy back 91/86 for about 0.05, sell the 99/94 put spread for about 0.25. Net new credit 0.20; total credit 1.15; maximum loss falls to 5.00 - 1.15 = 3.85; but the profit zone shrinks to 99 to 109 and a reversal to 98 would hurt the new puts.

Neither choice is "right"; the adjustment buys only 0.20 of relief for a much narrower range, and a continued move to 112 loses close to the full 3.85 either way. Exclusions: commissions, slippage on four-leg orders, taxes.

Common mistake

Practice activity

On paper: a stock at $50, 40 DTE. You sell the 45/42 put spread for 0.40 and the 55/58 call spread for 0.35. Calculate total credit, maximum loss, both break-evens, approximate POP and return on risk, and how many condors a $15,000 account can hold with a 2 percent risk budget per position.

Key takeaways

• An iron condor is two credit spreads; maximum loss is width minus total credit, and POP is high because the payoff ratio is poor.
• An iron butterfly sells at the money: more credit, narrower zone, lower POP.
• Size by maximum loss against a fixed percentage of the account; round down.
• Rolling the untested side buys a little credit for a narrower zone; decide the exit rule before entry.

Next step

The next lesson turns from strike structure to time structure: calendar and diagonal spreads that trade the difference in decay and implied volatility between two expiries.