{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,22]],"date-time":"2026-10-22T17:40:02Z","timestamp":1792690802096,"version":"4.5.0"},"posted":{"date-parts":[[2026]]},"group-title":"SSRN","reference-count":0,"publisher":"Elsevier BV","license":[{"start":{"date-parts":[[2026,1,1]],"date-time":"2026-01-01T00:00:00Z","timestamp":1767225600000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/www.uspto.gov\/ip-policy\/copyright-policy\/copyright-basics"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:p>We ask when portfolio optimisation beats equal weighting for European sector portfolios that follow sector-level versions of the EU Climate Transition and Paris-aligned benchmark rules. Using 19 STOXX Europe 600 sector ETFs, Eurostat emission intensities and public regime indicators for 2013-2026, we find that the carbon rules are cheap: halving the carbon intensity of 1\/N costs 0.02 in Sharpe ratio, and the cost does not rise in stress. The value of optimisation depends on the market phase. Minimum-variance and mean-CVaR portfolios beat 1\/N in crisis months but trail it by 19-21% a year after the market falls 10% below its peak, mostly because their market beta is low; model-based stress signals show a weaker version of this pattern. Robust optimisation and regime switches do not exploit it.<\/jats:p>","DOI":"10.2139\/ssrn.7655498","type":"posted-content","created":{"date-parts":[[2026,10,22]],"date-time":"2026-10-22T16:45:51Z","timestamp":1792687551000},"source":"Crossref","is-referenced-by-count":0,"title":["When Does Portfolio Optimisation Pay under Carbon Constraints? Evidence from Paris-Aligned European Sector Portfolios"],"prefix":"10.2139","author":[{"ORCID":"https:\/\/orcid.org\/0009-0000-9681-5324","authenticated-orcid":true,"given":"Seyed Parsa","family":"Ehtesham Hoseini","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"78","container-title":[],"original-title":[],"deposited":{"date-parts":[[2026,10,22]],"date-time":"2026-10-22T16:45:51Z","timestamp":1792687551000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.ssrn.com\/abstract=7655498"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026]]},"references-count":0,"URL":"https:\/\/doi.org\/10.2139\/ssrn.7655498","relation":{},"subject":[],"published":{"date-parts":[[2026]]},"subtype":"preprint"}}