The central finding is that the optimisation costs little. Over the year to August 2026, the Co₂liseum portfolio maintained a lower – and therefore better – transition score of 1.75 compared to the index’s 2.96, while returning 1.59% gross, matching the benchmark to within a few basis points (before transaction costs).
We set both against a live market Paris-Aligned Benchmark (PAB) ETF, and the comparison showed the two portfolios are not simply greener or less green than each other, but optimised on different objectives. The PAB leads on current emissions, cutting the index’s intensity by 56%; the Co₂liseum book leads on forward commitments, carrying the lowest projected carbon intensity to 2050 and a heavier weight of issuers with validated net-zero targets.
The practical takeaway is that meaningful transition improvement does not require large sector exclusions or a material sacrifice in portfolio characteristics — the harder problem is selecting the right issuers within sectors, and deciding which transition data is worth paying to incorporate.
