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Asset pricing theory originated from classical valuation methods, but its modern scientific basis was established by the Modern Portfolio Theory (MPT) school in the 1950s. Pioneered by Harry Markowitz, MPT introduced mean-variance optimization and formalized the trade-off between risk and return, providing a foundational framework for portfolio choice and equilibrium pricing. This paradigm set the stage for subsequent models that sought to explain asset prices in a systematic manner.
The Capital Asset Pricing Model (CAPM) school emerged in the 1960s as the dominant paradigm, developed by William Sharpe, John Lintner, and others. CAPM posited that an asset's expected return is linearly related to its exposure to market risk, captured by the beta coefficient. It became the standard model for assessing risk-adjusted returns and influenced both academic research and practical finance for decades, despite empirical shortcomings.
In response to CAPM's limitations, the Arbitrage Pricing Theory (APT) school arose in the 1970s, introduced by Stephen Ross. APT relied on arbitrage arguments rather than equilibrium assumptions, allowing for multiple risk factors and offering a more flexible multifactor approach. Simultaneously, the Consumption-Based Asset Pricing school gained prominence, linking asset prices to macroeconomic consumption through stochastic discount factors, as advanced by researchers like Robert Lucas and Douglas Breeden, integrating general equilibrium theory into finance.
Empirical challenges led to the Factor Model school, exemplified by the Fama-French three-factor model and its extensions, which identified size and value factors beyond market risk. Concurrently, the Behavioral Asset Pricing school developed as a rival paradigm, incorporating insights from psychology to explain anomalies such as excess volatility, momentum, and bubbles, drawing from work by scholars like Richard Thaler and Robert Shiller.
Contemporary asset pricing theory is characterized by the coexistence of these rival schools. Stochastic discount factor frameworks often synthesize elements from consumption-based and factor models, while behavioral approaches continue to inform empirical research. The field remains dynamic, with ongoing debates between neoclassical and behavioral perspectives, and innovations in data analysis and theoretical integration shaping its evolution.