Nº 21-91: Building Benchmark Portfolios with Decreasing Carbon Footprints

In this paper, we build portfolios with decreasing carbon footprint, which passive investors can use as new Paris-consistent (PC) benchmarks and have the same risk- adjusted returns as business as usual (BAU) benchmarks. As the distribution of firms' carbon intensity is very skewed, excluding a small fraction of highly polluting firms can massively reduce the carbon footprint of a portfolio of corporate stocks. We identify the worst polluters globally, exclude them from the portfolio, and re- allocate the proceeds so as to keep sectoral and regional exposures similar to those of the business as usual (BAU) benchmark. This approach limits divestment from corporates in Emerging Countries that would result from implementing exclusions and reinvestment without the objective of preserving regional exposures. We show that reducing the carbon footprint of the portfolio by 64% in 10 years would be obtained by excluding sequentially up to 11% of the corporates, which together amount to less than 6% of the global market portfolio. While this reallocation preserves regional and sectoral exposures similar to those of the BAU benchmark, it does not change its risk-adjusted return. We define PC benchmark portfolios at the global level, for Emerging Countries, Europe, North America, and the Pacific.