Equity portfolios is a fundamental concept within financial economics and investment management, denoting a collection of equity securities assembled and managed to achieve specific investment objectives. As a research area, it systematically investigates the principles of portfolio construction, management strategies, performance evaluation, risk characteristics, and the impact of diverse portfolio structures—spanning from broadly diversified, index-tracking compositions to highly concentrated holdings with specific strategic focuses (e.g., sector, quality)—on investment outcomes. Understanding equity portfolios is central to developing effective investment strategies, managing risk, optimizing asset allocation, and analyzing the relationship between portfolio characteristics and financial performance.