Risks of Delta- and Gamma-Neutral Calendar Spreads for Vega Trading
Summary
The document examines whether a calendar spread can provide a stable way to trade changes in implied volatility while remaining delta- and gamma-neutral. The responses explain that neutrality holds only under particular market conditions and can deteriorate as spot, time, or implied volatility changes. Keeping the position neutral may require adjustments, which add transaction costs and operational complexity.
Calendar spreads also carry relative implied-volatility risk across expiries, and their vega exposures do not necessarily combine in a simple way. The responses identify further sensitivity to dividends and interest rates, and caution that a calendar spread is a time-spread position as well as a volatility trade. A gamma-neutral ratio spread is offered as an alternative with its own exposures, including skew and changing neutrality; butterflies and straddles are also mentioned for short-vega positions. These are qualitative observations, not a tested comparison, and the examples do not specify a complete trading or risk-management plan.
Key ideas
- A calendar spread’s delta and gamma neutrality applies only at a particular spot level and time.
- Spot moves, time passage, and volatility changes can disrupt neutrality and prompt rebalancing.
- Calendar spreads expose traders to volatility differences across expiries, as well as rate and dividend changes.
- A gamma-neutral ratio spread may be more stable but has skew exposure and can lose neutrality over time.
- Butterflies and straddles are also mentioned as structures for short-vega trades.
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# Delta Neutral / Gamma Neutral Positions # Delta Neutral / Gamma Neutral Positions I've been trying to find out more about options positions which are both delta neutral and gamma neutral--created with some kind of calendar spread. Supposedly, such a trade will be perfectly hedged with relation to the underlying so that the value of the position will change only through a change in vega and possibly a small amount of theta. This would seem to be a good way to trade reversions of implied volatility...creating a positive vega position when betting on increasing implied volatility and creating a negative vega position when betting on decreasing implied volatility. It sounds like this would be a superior way to trade volatility since being gamma neutral would remove the need for continuous delta hedging. However, I don't read much about people doing this. What am I missing? ## Answer by derenik (score 9) https://quant.stackexchange.com/a/10484 Calendar spreads have a number of disadvantages for trading Vega: - Vega in different months are generally not additive, some traders use root-time-Vega but it does not remove the additional risk. - You are trading time spread not just volatility, so be careful - Calendar spreads are affected by dividends and rate changes - another source of risk. - A gamma-neutral calendar spread is only neutral at a particular time and spot price. Options in different month have different Speed (DgammaDspot) and Color (dgammaDtime) which means that your position will be dis-balanced quickly. Take a look at gamma-neutral ratio spread. It is much more stable and does not require frequent adjustments. It will be close to Vega-neutral as well but it's long Vomma so the position makes money with any change in volatility. The position will also have some residual delta which you can neutralize by trading stock. E.g. - Short 10 puts at strike X - Long 12 puts at a lower strike Y Disadvantage will be the skew risk (relative changes in IV of strikes X and Y). It also loses neutrality over time so some adjustments will be necessary if you hold the position for days/weeks. Butterflies and straddles are also good for short Vega plays. Make sure you gave them enough consideration before moving over to more complex stuff. ## Answer by airguru (score 3) https://quant.stackexchange.com/a/10477 You can construct delta and gamma neutral option portfolio, but: - It won't generally stay neutral forever, so you would still have to constantly rebalance it by trading additional options (thus paying more transaction costs and creating mess in the portofolio). Anything will break the neutrality - underlying move, time passage, implied volatility change etc. - Since you are trading different options, you gain additional risk exposure in implied volatility spreads. If you want to have large vega but small gamma, you can always trade options with long time to expiry. And conversely by trading options with short time to expiry you can have large gamma while having only small vega exposure.
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