Operator Deep Smoothing for Implied Volatility

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Operator Deep Smoothing for Implied Volatility

Ruben Wiedemann
Antoine Jacquier
Lukas Gonon
Published on 6/17/2024
Options
Equities
United States (US)
Machine learning
Deep learning
AI
Volatility effect

The paper introduces operator deep smoothing, a novel approach for implied volatility smoothing that leverages neural operators to directly map observed option data to smooth, no-arbitrage surfaces. Unlike traditional methods that require per-instance optimization (e.g., SVI calibration), this method trains a single graph neural operator (GNO) offline on historical data, enabling fast online inference. The key innovation is the use of neural operators, which are discretization-invariant and can handle the varying number and spatial arrangement of option quotes that occur naturally in markets. The authors adapt the GNO architecture to accept point clouds of implied volatilities with their coordinates (time-to-expiry and log-moneyness) and output a continuous surface. Training is performed on ten years of intraday S&P 500 options data, with a loss function that combines mean squared error against observed quotes and penalty terms for calendar and butterfly arbitrage violations. The trained model (with ~100k parameters) achieves state-of-the-art accuracy, outperforming the industry-standard SVI parametrization and matching the performance of per-surface neural networks, while being significantly faster at inference. The method also demonstrates robustness to input subsampling and generalizes well to other US indices without retraining. This work opens the door for using neural operators in financial engineering, particularly for tasks involving irregularly sampled spatial data, and provides a practical tool for practitioners needing fast, reliable implied volatility surfaces.

Highlights

  • 1Introduces operator deep smoothing, a novel method for implied volatility smoothing using neural operators, enabling discretization-invariant interpolation of raw option data.
  • 2Adapts the graph neural operator (GNO) architecture to map observed volatilities directly to smoothed surfaces, bypassing instance-by-instance optimization.
  • 3Demonstrates high accuracy on ten years of intraday S&P 500 options data with a single model instance (~100k parameters), outperforming SVI and competing with per-surface neural networks.
  • 4Ensures no-arbitrage constraints (calendar and butterfly) are satisfied and shows robustness to subsampling of inputs, mimicking outlier removal.
  • 5Generalizes to end-of-day data for S&P 500 and three other major US indices without retraining, highlighting transferability.

Methods

  • M
    Graph Neural Operator (GNO) architecture for discretization-invariant function approximation.
  • M
    Operator deep smoothing framework: trains a neural operator to map observed volatility points (with coordinates) to a smooth surface, using a loss function combining data fidelity and no-arbitrage penalties.
  • M
    Training on historical intraday S&P 500 options data with varying numbers and spatial arrangements of quotes, using mini-batch gradient descent.
  • M
    Evaluation against SVI (industry standard) and per-surface neural network baselines, with metrics including absolute error and no-arbitrage violation scores.

Results

  • R
    The trained operator achieves lower mean absolute error (MAE) on held-out S&P 500 data compared to SVI and is competitive with per-surface neural networks.
  • R
    No-arbitrage constraints (calendar and butterfly) are satisfied on the vast majority of test surfaces, with violation rates below 1%.
  • R
    The model is robust to random subsampling of input quotes, maintaining accuracy even when 50% of points are removed.
  • R
    Generalizes to out-of-sample indices (e.g., DJIA, NASDAQ, Russell 2000) without retraining, achieving MAE comparable to S&P 500 performance.
  • R
    A single model instance processes over 60 million volatility datapoints across ten years, demonstrating scalability and efficiency.
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