PurposeThis study aims to examine the Securities and Exchange Commission’s final rule in Modernization of Beneficial Ownership Reporting, which reduced the time for significant public company shareholders to file Schedule 13D (effective February 5, 2024). The authors corroborate prior results under the historic 10-day maximum reporting regime and provide updated academic analysis regarding how the five-day deadline between the “triggering” event, accumulating 5% of the outstanding shares and public disclosure of that event will affect abnormal returns.Design/methodology/approachThis empirical archival study uses publicly available data.FindingsThe analyses show that changing from a 10-day to a 5-day Schedule 13 disclosure window will reduce activist investors’ opportunity to profit by legally delaying the filing of Schedule 13D. These excess returns for delay exist regardless of the profitability or size of the target firm or the shareholder’s disclosed reason for filing. The authors conclude that accelerating the timing of the disclosure window is an improvement that is in the best interest of the general investing public.Originality/valueTo the authors’ knowledge, this is the only academic study of Schedule 13D filings to include the postpandemic period. As such, the authors establish an updated “baseline projection” for expectations regarding how the Modernization final rule will impact activist investors and stock returns under a five-day reporting regime. In addition, the authors measure and test abnormal returns after considering differences between “triggering” events and filing dates of Schedule 13Ds in the sample rather than grouping all filings. This approach allows the authors to account for the time difference between the triggering event and the filing date.