Michael Brennan is a prominent figure in the field of financial economics, best known for his contributions to asset pricing theory and portfolio management. His research has significantly influenced our understanding of how assets are valued in financial markets and how investors should construct optimal portfolios. Brennan’s early work focused on developing and testing models of asset pricing. He challenged the traditional Capital Asset Pricing Model (CAPM) by incorporating factors beyond market risk. He argued that investors care about consumption and that changes in consumption opportunities can influence asset prices. This led to his development of intertemporal asset pricing models, which consider how asset prices respond to changes in investment opportunities over time. One of his most influential papers, co-authored with Eduardo Schwartz, explored the valuation of natural resource investments. They showed how the value of a natural resource project, such as an oil well, depends not only on the expected future prices of the resource but also on the flexibility to delay or abandon the project. This work pioneered the application of option pricing theory to real assets and had a profound impact on corporate finance and investment decisions in resource-intensive industries. Brennan’s research also delved into the complexities of portfolio choice. He explored how investors should allocate their wealth across different assets, considering factors such as transaction costs, taxes, and private information. His work demonstrated that optimal portfolio strategies can be significantly affected by these real-world constraints. He developed models that allowed for the consideration of non-traded assets, such as human capital, in the portfolio optimization process, reflecting a more realistic investment landscape. Furthermore, Brennan made substantial contributions to the understanding of market microstructure and the impact of trading frictions on asset prices. He investigated how factors such as order flow, bid-ask spreads, and market depth influence price discovery and market efficiency. This research helped to explain some of the anomalies observed in financial markets and provided insights into how market design can be improved to enhance market quality. Throughout his career, Brennan has consistently advocated for a rigorous and empirical approach to financial economics. His work has been characterized by its theoretical depth, its practical relevance, and its careful attention to empirical testing. His research has been published in leading academic journals and has been widely cited by other researchers and practitioners. Michael Brennan’s contributions have profoundly shaped our understanding of finance and have had a lasting impact on the field. He has significantly contributed to the evolution of asset pricing, portfolio management, and market microstructure theory.