{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T08:47:53Z","timestamp":1791794873171,"version":"4.3.4"},"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>Comparisons of portfolio methods often report a single best-performing method from a fixed out-of-sample evaluation window. We use terminal-date perturbations to distinguish changes in the certainty-equivalent return (CEQ) winner from the economic loss incurred by retaining the initial winner, thereby separating ordinal ranking instability from cardinal economic loss. Using 17 U.S. industry portfolios and 14 developed-country market portfolios from the Kenneth R. French Data Library, we find that a 12-month terminal-date shift changes the winner in 21.4% and 16.7% of endpoint comparisons, respectively. In contrast, endpoint loss exceeds 25 annualized basis points (bp) in 6.0% and 11.1%. A separate prospective analysis asks how often the preceding-window winner is also the best method in the subsequent window; the corresponding rates are 38.7% for the U.S. sample and 25.9% for the international sample. Taken together, the results show that changes in the historical winner need not correspond to large economic losses, while past winner status does not consistently identify the method that performs best in the subsequent window.<\/jats:p>","DOI":"10.2139\/ssrn.7594441","type":"posted-content","created":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T08:22:12Z","timestamp":1791793332000},"source":"Crossref","is-referenced-by-count":0,"title":["Reproducibility of Portfolio Method Comparisons: Terminal-Date Sensitivity and Endpoint Loss"],"prefix":"10.2139","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-5763-8802","authenticated-orcid":true,"given":"Jan","family":"Zasadil","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"78","container-title":[],"original-title":[],"deposited":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T08:22:12Z","timestamp":1791793332000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.ssrn.com\/abstract=7594441"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026]]},"references-count":0,"URL":"https:\/\/doi.org\/10.2139\/ssrn.7594441","relation":{},"subject":[],"published":{"date-parts":[[2026]]},"subtype":"preprint"}}