Deep Parametric Portfolio Policies

Deep Parametric Portfolio Policies
Author: Frederik Simon
Publisher:
Total Pages: 0
Release: 2023
Genre:
ISBN:

We directly optimize portfolio weights as a function of firm characteristics via deep neural networks by generalizing the parametric portfolio policy framework. Our results show that network-based portfolio policies result in an increase of investor utility of between 30 and 100 percent over a comparable linear portfolio policy, depending on whether portfolio restrictions on individual stock weights, short-selling or transaction costs are imposed, and depending on an investor's utility function. We provide extensive model interpretation and show that network-based policies better capture the non-linear relationship between investor utility and firm characteristics. Improvements can be traced to both variable interactions and non-linearity in functional form. Both the linear and the network-based approach agree on the same dominant predictors, namely past return-based firm characteristics.

Parametric Portfolio Policies

Parametric Portfolio Policies
Author: Michael W. Brandt
Publisher:
Total Pages: 50
Release: 2010
Genre:
ISBN:

We propose a novel approach to optimizing portfolios with large numbers of assets. We model directly the portfolio weight in each asset as a function of the asset's characteristics. The coefficients of this function are found by optimizing the investor's average utility of the portfolio's return over the sample period. Our approach is computationally simple, easily modified and extended, produces sensible portfolio weights, and offers robust performance in and out of sample. In contrast, the traditional approach of first modeling the joint distribution of returns and then solving for the corresponding optimal portfolio weights is not only difficult to implement for a large number of assets but also yields notoriously noisy and unstable results. Our approach also provides a new test of the portfolio choice implications of equilibrium asset pricing models. We present an empirical implementation for the universe of all stocks in the CRSP-Compustat dataset, exploiting the size, value, and momentum anomalies.

Online-Appendix to

Online-Appendix to
Author: Thomas Gehrig
Publisher:
Total Pages: 102
Release: 2019
Genre:
ISBN:

We provide examples of pitfalls for parametric portfolio policies as introduced by Brandt, Santa Clara and Valkanov. For the leading case of constant relative risk aversion (CRRA) strong assumptions on the properties of the returns, the variables used to implement the parametric portfolio policy and the parameter space are necessary to obtain a well defined optimization problem. As possible remedies for practical work various extensions of CRRA Bernoulli utility to the real line are discussed. Also prospect theory is suggested as an alternative approach. We observe that for low levels of relative risk aversion expected utility turns non-monotonic and an interior maximum need not exist. We provide economic conditions that overcome such empirical problems and that guarantee the effectiveness of the approach more broadly. We illustrate our concerns by applying parametric portfolio policies to a large universe of stocks.Full paper is available at: "https://ssrn.com/abstract=3081100" https://ssrn.com/abstract=3081100.

Dynamic Parametric Portfolio Policy

Dynamic Parametric Portfolio Policy
Author: Stefano Dova
Publisher:
Total Pages: 46
Release: 2018
Genre:
ISBN:

This paper extends the parametric portfolio approach by Brandt et al. (2009) to a continuous time setting. I model stocks as call options on firm assets and choose, as characteristics, the three main drivers of stock returns under the structural credit risk model approach: debt maturity, levered asset growth, and asset volatility. I then solve for the parametric portfolio weights to be assigned to these three characteristics in a dynamic setting. I make three contributions: 1) extract characteristics for portfolio allocation from a portfolio of credit-risky single stocks, 2) solve the dynamic programming problem for the parametric portfolio weights, and 3) show that, accounting for credit risk, in a multi-period framework, achieves better Sharpe ratios than naive strategies such as EW and VW as well as comparable Sharpe ratios to those of portfolios built on size, book-to-market, momentum and gross profitability characteristics.

Deep Reinforcement Learning-based Portfolio Management

Deep Reinforcement Learning-based Portfolio Management
Author: Nitin Kanwar
Publisher:
Total Pages: 71
Release: 2019
Genre:
ISBN:

Machine Learning is at the forefront of every field today. The subfields of Machine Learning called Reinforcement Learning and Deep Learning, when combined have given rise to advanced algorithms which have been successful at reaching or surpassing the human-level performance at playing Atari games to defeating multiple times champion at Go. These successes of Machine Learning have attracted the interest of the financial community and have raised the question if these techniques could also be applied in detecting patterns in the financial markets.Until recently, mathematical formulations of dynamical systems in the context of Signal Processing and Control Theory have attributed to the success of Financial Engineering. But because of Reinforcement Learning, there has been improved sequential decision making leading to the development of multistage stochastic optimization, a key component in sequential portfolio optimization (asset allocation) strategies.In this thesis, we explore how to optimally distribute a fixed set of stock assets from a given set of stocks in a portfolio to maximize the long term wealth of the Deep Learning trading agent using Reinforcement Learning. We treat the problem as context-independent, meaning the learning agent directly interacts with the environment, thus allowing us to apply model free Reinforcement Learning algorithms to get optimized results. In particular, we focus on Policy Gradient and Actor Critic Methods, a class of state-of-the-art techniques which constructs an estimate of the optimal policy for the control problem by iteratively improving a parametric policy.We perform a comparative analysis of the Reinforcement Learning based portfolio optimization strategy vs the more traditional "Follow the Winner", "Follow the Loser", and "Uniformly Balanced" strategies, and find that Reinforcement Learning based agents either far out perform all the other strategies, or behave as good as the best of them.The analysis provides conclusive support for the ability of model-free Policy Gradient based Reinforcement Learning methods to act as universal trading agents.

Portfolio Choice Under Local Factors

Portfolio Choice Under Local Factors
Author: Carlos Castro
Publisher:
Total Pages: 24
Release: 2009
Genre:
ISBN:

This paper extends the parametric portfolio policy approach to optimizing portfolios with large numbers of assets, derived by Brandt et al. (2007). The proposed approach incorporates unobserved effects into the portfolio policy function. These effects measure the importance of unobserved heterogeneity for exploiting the difference between groups of assets. The source of the heterogeneity is local priced factors such as industry or country. The statistical model derived allows to test the importance of such local factors in portfolio optimization. Preliminary evidence indicates no significant gains of tilting a benchmark assignment (value weighted or equal weighted portfolio) to a particular industry.