ESG Constraints in Portfolio Optimization

Over the past decade, the growing reference to Environmental, Social and Governance considerations into portfolio optimization has become a key trend of contemporary investment strategy. Environmental, Social, and Governance (ESG) criteria offer a constraint-based standard of assessing how sustainability factors influence the portfolio optimization and the feasible set of optimal solutions. Yet the impact of ESG constraints on portfolio efficiency remains contested. Using data from Bloomberg for a set of ten stocks across a similar sector, this paper aims to compare shifts in three portfolio regions: efficient frontiers, inefficient frontier and minimal variance frontier, under several different constraints. And ESG scores in this paper is treated as a quantitative constraint used to assess the balance in ESG scores in between ethical compliance and optimized portfolio efficiency. Both the Markowitz Model is used to calculate portfolio performance under these varying regulatory constraints. The findings provide actionable insights for investors seeking to align sustainability goals with financial performance, while highlighting avenues for future research on dynamic ESG constraint modeling.