Breaking the Dimensional Barrier: A Pontryagin-Guided Direct Policy Optimization for Continuous-Time Multi-Asset Portfolio Choice

ArXiv ID: 2504.11116 “View on arXiv”

Authors: Unknown

Abstract

We introduce the Pontryagin-Guided Direct Policy Optimization (PG-DPO) framework for high-dimensional continuous-time portfolio choice. Our approach combines Pontryagin’s Maximum Principle (PMP) with backpropagation through time (BPTT) to directly inform neural network-based policy learning, enabling accurate recovery of both myopic and intertemporal hedging demands–an aspect often missed by existing methods. Building on this, we develop the Projected PG-DPO (P-PGDPO) variant, which achieves nearoptimal policies with substantially improved efficiency. P-PGDPO leverages rapidly stabilizing costate estimates from BPTT and analytically projects them onto PMP’s first-order conditions, reducing training overhead while improving precision. Numerical experiments show that PG-DPO matches or exceeds the accuracy of Deep BSDE, while P-PGDPO delivers significantly higher precision and scalability. By explicitly incorporating time-to-maturity, our framework naturally applies to finite-horizon problems and captures horizon-dependent effects, with the long-horizon case emerging as a stationary special case.

Keywords: Pontryagin’s Maximum Principle (PMP), backpropagation through time (BPTT), neural network-based policy, Deep BSDE, projected PG-DPO, Equities (Portfolio choice)

Complexity vs Empirical Score

• Math Complexity: 9.5/10
• Empirical Rigor: 6.0/10
• Quadrant: Holy Grail
• Why: The paper relies heavily on advanced continuous-time mathematics like Pontryagin’s Maximum Principle and partial differential equations, warranting a high math score. It provides empirical comparisons and demonstrates the method on high-dimensional problems, though it lacks direct backtest code or live trading data, resulting in a moderate empirical score.

  flowchart TD
    A["Research Goal<br>High-dimensional<br>Continuous-time Portfolio Choice"] --> B["Methodology<br>Pontryagin-Guided Direct Policy Optimization<br>(PG-DPO)"]
    B --> C["Key Process<br>Combines Pontryagin's Maximum Principle (PMP)<br>with Backpropagation Through Time (BPTT)"]
    C --> D["Variant<br>Projected PG-DPO (P-PGDPO)<br>Projects costate estimates onto PMP conditions"]
    C --> E["Data/Inputs<br>Continuous-time multi-asset market data<br>Finite/Long-horizon constraints"]
    D --> F["Computation<br>Neural Network Policy Training<br>with reduced overhead & improved precision"]
    E --> F
    F --> G["Outcomes<br>1. Matches/Exceeds Deep BSDE accuracy<br>2. Recovers myopic & hedging demands<br>3. Scalable to high dimensions<br>4. Handles finite-horizon problems naturally"]