Aega, Sega & Rega

Contributor Image
Written By
Contributor Image
Written By
Dan Buckley
Dan Buckley is an US-based trader, consultant, and part-time writer with a background in macroeconomics and mathematical finance. He trades and writes about a variety of asset classes, including equities, fixed income, commodities, currencies, and interest rates. As a writer, his goal is to explain trading and finance concepts in levels of detail that could appeal to a range of audiences, from novice traders to those with more experienced backgrounds.

Aega, Sega, and Rega are advanced risk measures that go beyond traditional Greeks like Vega, Vanna, and Volga.


Key Takeaways – Aega, Sega, and Rega

  • Aega, Rega, and Sega provide more comprehensive risk analysis for options with volatility smiles.
  • They measure sensitivity to ATM volatility, risk reversal, and butterfly/strangle premium respectively.
  • These metrics offer better insights into exotic options and improve hedging strategies compared to traditional Greeks.



Aega, Sega, and Rega were introduced around 1997 to address limitations in conventional Black-Scholes Greeks – particularly when dealing with options smiles (i.e., implied volatility varies based on the strike price).

These measures provide a more thorough approach to quantifying and managing risk in options trading, especially for complex or exotic options.



Aega (∂V/∂σA)

Sensitivity of option value to changes in at-the-money (ATM) volatility.

Rega (∂V/∂α)

Sensitivity to changes in risk reversal, which represents the slope of the volatility smile.

Sega (∂V/∂β)

Sensitivity to changes in butterfly or strangle premium, which represents the curvature of the volatility smile.


Key Advantages of Using Aega, Rega, and Sega

  1. More accurate risk quantification
  2. Improved hedging capabilities
  3. Better intuition for trading and P&L generation
  4. Better understanding of exotic products
  5. More appropriate reserve holding
  6. Generalization of Vanna and Volga concepts to volatility smiles


Use for Knock Out and Reverse Knocket Out Options

These measures are handy for understanding the risk profile of exotic options.

For example:

  • A regular Knock Out (KO) option might show near-zero Vega but significant Rega exposure.
  • A Reverse Knock Out (RKO) option might display zero Vega but substantial Sega exposure.

Aega, Rega, and Sega relate to important aspects of the volatility smile:

  1. (σA, α, β) represent the level, slope, and curvature of the smile, respectively.
  2. They also correspond to the standard deviation, skew, and kurtosis of the implied probability distribution (to first order).

In practice, traders often use finite differences rather than ratios to calculate these measures, as it provides more tangible results in terms of monetary impact.

These concepts aren’t just academic or theoretical.

They’ve gained widespread adoption in the financial industry since around 2005, proving valuable for risk management, pricing, and trading strategies in options markets.

They have been implemented in various proprietary models and have been used in high-stakes situations, such as analyzing complex equity derivatives in major lawsuits.



By incorporating Aega, Rega, and Sega into their analysis, options traders and risk managers can gain a more nuanced understanding of their positions’ sensitivity to changes in volatility smile parameters, which can lead to more informed decision-making and potentially improved performance.