{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T17:06:55Z","timestamp":1786122415117,"version":"build-2736575974"},"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>Section 13(f) requires large institutional managers to disclose their US equity holdings quarterly. The rule is fifty years old, applies identically to filers differing by more than two orders of magnitude in portfolio breadth, and is defended on the ground that disclosure is costly. I test whether these disclosures move prices, using a negative control the regime supplies: Norges Bank Investment Management files quarterly reports containing no positions, under confidential treatment, the information table following a year later. Across 29,421 securityevents from 894 filings by 26 managers between 2013 and 2026, newly disclosed and materially increased positions earn a two-day abnormal return of-7.0 basis points relative to that control when security-events are weighted equally, and between-2 and-6 basis points when filings are weighted equally. The control returns 0.7 basis points, close to the zero an empty filing would ideally produce. None of the alternative weighting estimates is significant at five per cent, although some six-factor fixed-effect specifications reach that threshold; all carry the same sign. The estimates differ because control filings hold about 1,100 securities each and treatment filings about 33. There is no gradient in position size relative to trading volume, where execution costs should bind hardest. Under the preferred six-factor specifications the confidence intervals generally exclude effects more negative than about fifteen to sixteen basis points, while the market model is considerably less precise. Security-event and filing weighting answer different questions, and the two estimates are reported side by side rather than reconciled.<\/jats:p>","DOI":"10.2139\/ssrn.7204639","type":"posted-content","created":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T10:00:37Z","timestamp":1786096837000},"source":"Crossref","is-referenced-by-count":0,"title":["What Does Mandatory Portfolio Disclosure Reveal? A Placebo Test of the 13F Regime"],"prefix":"10.2139","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-8477-9393","authenticated-orcid":true,"given":"Boon Chuan","family":"Lim","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"78","container-title":[],"original-title":[],"deposited":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T10:00:37Z","timestamp":1786096837000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.ssrn.com\/abstract=7204639"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026]]},"references-count":0,"URL":"https:\/\/doi.org\/10.2139\/ssrn.7204639","relation":{},"subject":[],"published":{"date-parts":[[2026]]},"subtype":"preprint"}}