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Asset Pricing: Machine Learning

Paper Session

Sunday, Jan. 5, 2025 8:00 AM - 10:00 AM (PST)

San Francisco Marriott Marquis, Yerba Buena Salon 8
Hosted By: American Finance Association
  • Bryan Kelly, Yale University

Asset Embeddings

Xavier Gabaix
,
Harvard University
Ralph Koijen
,
University of Chicago
Robert Richmond
,
New York University
Motohiro Yogo
,
Princeton University

Abstract

Firm characteristics are ubiquitously used in economics. These characteristics are often
based on readily-available information such as accounting data, but those reflect only a part
of investors’ information set. We show that useful information about firm characteristics is
embedded in investors’ holdings data and, via market clearing, in prices, returns, and trading
data. Based on insights from the recent artificial intelligence (AI) and machine learning (ML)
literature, in which unstructured data (e.g., words or speech) are represented as continuous
vectors in a potentially high-dimensional space, we propose to learn asset embeddings from
investors’ holdings data. Indeed, just as documents arrange words that can be used to uncover
word structures via embeddings, investors organize assets in portfolios that can be used to
uncover firm characteristics that investors deem important via asset embeddings. This broad
theme provides a natural bridge to connect recent advances in the fields of AI and ML to finance
and economics. Specifically, we show how language models, including transformer models that
feature prominently in large language models such as BERT and GPT, can handle numerical
information, and in particular holdings data to estimate asset embeddings. We provide initial
evidence on the value added of asset embeddings through a series of applications in the con-
text of firm valuations, return comovement, and uncovering asset substitution patterns. As a
by-product, the models generate investor embeddings, which can be used to measure investor
similarity. We propose a programmatic list of potential applications of asset and investor em-
beddings to finance and economics more generally.

The Expected Returns on Machine-Learning Strategies

Vitor Azevedo
,
University of Kaiserslautern-Landau
Christopher Hoegner
,
Technical University of Munich
Mihail Velikov
,
Pennsylvania State University

Abstract

We estimate the expected returns of machine learning-based anomaly trading strategies, accounting for three factors often overlooked in the previous literature: transaction costs, post-publication decay, and the post-decimalization era of high liquidity. Despite a cumulative performance reduction averaging about 57% when accounting for these three factors, sophisticated machine learning strategies remain profitable, particularly those employing Long Short-Term Memory (LSTM) models. We estimate that our most effective strategy, the one based on an LSTM model with one hidden layer, has an expected gross (net) Sharpe Ratio of 0.94 (0.84). Our findings contrast with previous literature suggesting that machine learning strategies are unprofitable after accounting for economic constraints and demonstrate persistent return predictability that cannot be explained by common risk factors or limits to arbitrage.

What Drives Trading in Financial Markets? A Big Data Perspective

Anton Lines
,
Copenhagen Business School
Shikun (Barry) Ke
,
Yale University

Abstract

We use deep Bayesian neural networks to investigate the determinants of trading activity in a large sample of institutional equity portfolios. Our methodology allows us to evaluate hundreds of potentially relevant explanatory variables, estimate arbitrary nonlinear interactions among them, and aggregate them into interpretable categories. Deep learning models predict trading decisions with up to 86% accuracy out-of-sample, with macroeconomic conditions and market liquidity
together accounting for most (66 − 91%) of the explained variance. Stock fundamentals, firm-specific corporate news, and analyst forecasts have comparatively low explanatory power. Our results suggest that macroeconomic risk and market microstructure considerations are the most crucial factors in understanding institutional trading patterns.

Discussant(s)
Markus Pelger
,
Stanford University
Andrew Chen
,
Federal Reserve Board
Yinan Su
,
Johns Hopkins University
JEL Classifications
  • G1 - General Financial Markets