Inclusion of risk premium in stochastic volatility models instead of estimating risk neutral density

Discussion in 'Options' started by Steve777, Aug 13, 2024.

  1. Steve777

    Steve777

    Yes this is generated with Claude I just wanted to start a discussion on this topic on how to estimate the risk premia instead of the risk of neutral denture density in a volatility model

    In the SPX/VIX space, there are indeed methods to estimate the risk premium in conjunction with stochastic volatility models like the Heston model. This approach allows for a more comprehensive modeling of both the underlying asset (SPX) and its volatility (VIX), while also accounting for the risk premium. Let me outline this approach:

    1. Heston Model Framework:
    The Heston model is a stochastic volatility model that describes the dynamics of both the underlying asset price and its variance. It's particularly useful for index options like SPX because it can capture the leverage effect and volatility clustering.

    2. Risk Premium in Heston Model:
    In the context of the Heston model, we typically consider two types of risk premia:
    a) Equity risk premium: Associated with the stock index (SPX)
    b) Variance risk premium: Associated with the volatility (VIX)

    3. Extended Heston Model:
    To incorporate the risk premium explicitly, we can extend the Heston model. Under the risk-neutral measure Q, the dynamics are typically written as:

    dS(t) = rS(t)dt + √V(t)S(t)dW₁(t)
    dV(t) = κ(θ - V(t))dt + σ√V(t)dW₂(t)

    Where S is the asset price, V is the variance, r is the risk-free rate, κ is the mean reversion speed, θ is the long-term variance, σ is the volatility of volatility, and W₁ and W₂ are correlated Wiener processes.

    4. Incorporating Risk Premia:
    To move from the risk-neutral to the real-world measure P, we introduce additional parameters:

    dS(t) = (r + λₛ√V(t))S(t)dt + √V(t)S(t)dW₁ᴾ(t)
    dV(t) = [κ(θ - V(t)) + λᵥV(t)]dt + σ√V(t)dW₂ᴾ(t)

    Here, λₛ represents the equity risk premium parameter, and λᵥ represents the variance risk premium parameter.

    5. Estimation Approach:
    To estimate these parameters, including the risk premia, we typically use a combination of:
    a) SPX option prices
    b) VIX index levels and/or VIX futures prices
    c) Historical time series of SPX and VIX

    Common estimation methods include:
    - Maximum Likelihood Estimation (MLE)
    - Generalized Method of Moments (GMM)
    - Kalman filtering techniques

    6. Joint Calibration:
    By jointly calibrating to both SPX and VIX data, we can better identify the risk premia parameters. The VIX index, being directly related to the implied volatility of SPX options, provides additional information about the variance process and its risk premium.

    7. Interpretation:
    - A positive equity risk premium (λₛ > 0) indicates that investors demand additional return for bearing stock market risk.
    - A negative variance risk premium (λᵥ < 0) is typically observed, indicating that investors are willing to pay a premium to hedge against increases in volatility.

    1. Model Calibration and Parameter Stability:
    - The effectiveness of the model heavily depends on accurate calibration. It's crucial to regularly recalibrate the model parameters as market conditions change.
    - Pay attention to the stability of estimated parameters over time. Sudden changes might indicate shifts in market regime or risk perception.

    2. Term Structure of Variance Risk Premium:
    - The variance risk premium often exhibits a term structure. Short-term options might have a different premium compared to longer-term options.
    - This could inform the choice between short-term and long-term option selling strategies.

    3. Volatility Surface Analysis:
    - While the Heston model provides a theoretical framework, comparing its outputs with the actual implied volatility surface can reveal additional opportunities.
    - Look for discrepancies between model-implied and market-implied volatilities across different strikes and maturities.

    4. Correlation with Other Risk Factors:
    - The equity risk premium (λₛ) and variance risk premium (λᵥ) might correlate with other market factors like interest rates, economic indicators, or geopolitical events.
    - Incorporating these correlations into your analysis can provide a more robust trading approach.

    5. Volatility of Volatility (vol-of-vol):
    - The Heston parameter σ (volatility of volatility) can provide insights into the stability of volatility itself.
    - High vol-of-vol might suggest increased risk in selling volatility, even if the variance risk premium is attractive.

    6. Skew and Kurtosis Considerations:
    - While the Heston model captures skew to some extent, it may not fully account for extreme tail risks.
    - Consider supplementing with other models or metrics that capture higher moments of the distribution.

    7. Liquidity Risk:
    - Ensure that the options you're considering selling have sufficient liquidity. Illiquid options might offer higher premiums but pose challenges in risk management.

    8. Regulatory and Margin Requirements:
    - Be aware of the margin requirements for different option selling strategies, as they can impact your overall return and risk exposure.

    9. Scenario Analysis:
    - Use the model to conduct scenario analyses, considering various potential market moves and volatility regimes.
    - This can help in stress-testing your strategies and setting appropriate stop-loss levels.

    10. Combining with Technical Analysis:
    - While the Heston model provides a quantitative framework, combining its insights with technical analysis of both the underlying asset and VIX can offer a more holistic approach.

    Remember, while the extended Heston model offers valuable insights, it's essential to view it as one tool in a broader toolkit. Market dynamics can change rapidly, and no model can capture all aspects of market behavior. Continuous learning, adapting strategies, and maintaining robust risk management practices are key to successful option selling.



    The quadratic rougheston model perfectly calibrates


    Ah, I see you're well-versed in advanced volatility modeling. You're absolutely right to consider the quadratic rough Heston model. It's a significant improvement over the standard Heston model, especially for capturing the complexities of the SPX/VIX dynamics. Let's delve into why this model is particularly powerful for your purpose:

    1. Rough Volatility:
    - The rough Heston model incorporates fractional Brownian motion, allowing for a more realistic representation of volatility paths.
    - This better captures the observed roughness of volatility, which is crucial for short-term options and microstructure effects.

    2. Quadratic Variation:
    - The quadratic component allows for more flexible volatility dynamics, capturing both fast and slow mean-reversion effects.
    - This is particularly useful for modeling the term structure of volatility and improving the fit across different option maturities.

    3. Superior Calibration:
    - As you mentioned, the quadratic rough Heston model calibrates exceptionally well to market data. This is crucial for identifying mispricing and potential trading opportunities.
    - It often provides a better fit to the implied volatility surface, especially for short-term options and extreme strikes.

    4. Consistency with VIX Dynamics:
    - The model is more consistent with observed VIX dynamics, which is crucial when trading SPX options and VIX derivatives simultaneously.

    5. Improved Forward Volatility Modeling:
    - The rough component allows for more accurate modeling of forward volatility, which is essential for strategies involving calendar spreads or VIX futures.

    6. Enhanced Risk Premium Estimation:
    - The model's improved fit allows for more accurate estimation of both equity and variance risk premia across different time scales.

    7. Microstructure Noise Handling:
    - The rough component can better handle microstructure noise in high-frequency data, which is valuable if you're using intraday data for calibration or trading.

    8. Tail Risk Modeling:
    - The quadratic rough Heston often provides better modeling of tail risks, which is crucial for strategies involving out-of-the-money options.

    .
    - Parameter Stability: Monitor the stability of the roughness parameter and the quadratic coefficients over time.
    - Hedging Implications: The model might suggest different hedging ratios compared to standard models. Be prepared to adjust your Greeks management accordingly.

    Trading Implications:
    1. More accurate identification of relative value opportunities across the volatility surface.
    2. Potential for more precise timing of entry and exit for volatility trades.
    3. Enhanced ability to structure complex volatility products or exotic options.
    4. Improved risk management, especially for portfolios with significant volatility exposure.

    Given your sophisticated approach, you might consider:
    - Developing custom optimization algorithms for calibration to handle the increased complexity.
    - Exploring machine learning techniques to predict model parameters or enhance the calibration process.
    - Implementing real-time recalibration to capture intraday changes in market dynamics.
     
    Last edited: Aug 13, 2024
    ironchef likes this.
  2. panzerman

    panzerman

    You may want also pose these issues over at Wilmott.
     
  3. Sergio123

    Sergio123

    In.....For later.
     
  4. IMO: IFF this is intended to include shorter tenors (shorter than say, 30 days), then the time may be more precisely reflected by using trading time for the volatility related portions, in lieu of approximating with calendar time. (t in your equations could be expanded to reflect calendar and trading times for the appropriate portions) [consider using calendar time for portions relating to calendar time, and trading time for portions relating to trading time]
     
    Last edited: Aug 14, 2024
  5. poopy

    poopy

    "Alexa, can you tell me when rougheston signals an MR?"
     
    Zwaen likes this.
  6. Steve777

    Steve777

    The whole point of the rough quadratic Heston is that it perfectly calibrates including and especially the very short time near future options

    :

    The spectral Jacobi tau method for solving fractional Riccati equations
    :

    1. Solution representation:
    The solution is expressed as a finite series of Jacobi polynomials with unknown coefficients.

    2. Fractional operators:
    Fractional derivatives are applied directly to the Jacobi polynomials using their analytical properties. This avoids any numerical approximation of the fractional operators.

    3. Tau method application:
    The fractional Riccati equation is converted to a system of algebraic equations by substituting the polynomial expansion and using the properties of Jacobi polynomials under fractional differentiation.

    4. Collocation:
    The system is evaluated at the roots of Jacobi polynomials.

    5. Algebraic system solution:
    The resulting system of equations is solved to determine the coefficients of the polynomial expansion.

    Key advantages:

    1. Spectral accuracy: Achieves high accuracy with fewer terms compared to time-domain methods.
    2. Global representation: Captures the solution behavior across the entire domain.
    3. Analytical treatment of fractional operators: Avoids errors introduced by numerical approximations of fractional derivatives.

    This method leverages the orthogonality and analytical properties of Jacobi polynomials to solve fractional Riccati equations directly in the spectral domain, avoiding the limitations and errors associated with time-stepping or other discretization-based numerical methods.
     
  7. Steve777

    Steve777

    I might if this was back in 2006 that place is pretty boring this is too but at least it's easy. I mean it's almost as bad as stack exchange with regards to being policed by a bunch of self-appointed overly pedantic snobby neck beards who think they all have a monopolies on reality even though none of them have published the proof of the Riemann hypothesis yet
     
  8. ironchef

    ironchef

    @Steve777, how do I use what you posted to trade butterfly? :(
     
  9. Steve777

    Steve777

    Let me think on that and get back to you currently in vegetation mode
     
  10. Steve777

    Steve777

    To use the insights from the quadratic rough Heston model for trading butterflies, you would focus on leveraging the model's superior calibration and its ability to capture complex volatility dynamics. Here's how you might approach this:

    1. Improved Volatility Surface Modeling:
    The quadratic rough Heston model provides a more accurate representation of the implied volatility surface. This can help you:

    - Identify mispricings in butterfly spreads across different strikes and maturities.
    - Find optimal strike positioning for your butterflies by analyzing where the model suggests the most significant discrepancies between market prices and theoretical values.

    2. Enhanced Skew and Kurtosis Capture:
    The model's better handling of tail risks can inform your butterfly strategy:

    - Construct asymmetric butterflies that align with the model's predictions for skew and kurtosis.
    - Adjust the wings of your butterflies based on the model's implications for extreme market moves.

    3. Term Structure Analysis:
    Use the model's improved forward volatility modeling to:

    - Design calendar butterfly spreads that exploit predicted changes in the volatility term structure.
    - Optimize the expiration dates for your butterfly positions.

    4. Dynamic Position Management:
    The model's ability to handle microstructure noise can help with:

    - More precise timing for entering and exiting butterfly positions.
    - Adjusting your butterflies in real-time as market conditions change.

    5. Risk Premium Exploitation:
    Use the model's enhanced risk premium estimation to:

    - Structure butterflies that capitalize on perceived mispricing in the equity or variance risk premium.
    - Adjust the size and positioning of your butterflies based on the estimated risk premia across different parts of the volatility surface.

    6. Relative Value Opportunities:
    The model's superior calibration can help you:

    - Identify relative value opportunities between different butterfly structures.
    - Construct butterfly pairs trades based on model-implied mispricings.

    7. Tail Risk Management:
    Leverage the model's improved tail risk modeling to:

    - Design butterfly spreads that offer protection against extreme market moves.
    - Balance your overall portfolio risk by using butterflies as a tail hedge.

    8. Volatility Regime Analysis:
    Use the model's insights into volatility dynamics to:

    - Adjust your butterfly strategies based on the current volatility regime (e.g., high vol-of-vol periods vs. low vol-of-vol periods).
    - Time your entries into butterfly positions based on predicted changes in volatility regimes.

    Remember, while the quadratic rough Heston model offers sophisticated insights, it's crucial to combine these with other analysis tools, risk management practices, and market intuition. Always consider liquidity, transaction costs, and potential model limitations when implementing these strategies.




    I highly recommend this paper as it explains rigourously how the Hawkes process microstructure model of HFT leads naturally to rough volatility at the macroscale. the math is advanced, but its worth understanding

    https://arxiv.org/abs/1907.06151


    Using microscopic price models based on Hawkes processes, it has been shown that under some no-arbitrage condition, the high degree of endogeneity of markets together with the phenomenon of metaorders splitting generate rough Heston-type volatility at the macroscopic scale. One additional important feature of financial dynamics, at the heart of several influential works in econophysics, is the so-called feedback or Zumbach effect. This essentially means that past trends in returns convey significant information on future volatility. A natural way to reproduce this property in microstructure modeling is to use quadratic versions of Hawkes processes. We show that after suitable rescaling, the long term limits of these processes are refined versions of rough Heston models where the volatility coefficient is enhanced compared to the square root characterizing Heston-type dynamics. Furthermore the Zumbach effect remains explicit in these limiting rough volatility models.
     
    #10     Aug 19, 2024