Item 4.01 Changes in Registrant’s Certifying Accountant. (a) Dismissal of Previous Independent Registered Public Accounting Firm On April 5, 2024, the audit committee of the board of directors (the “ Audit Committee”) of Arcturus Therapeutics Holdings Inc.’s (the “ Company” or “ Arcturus”) authorized the dismissal of Ernst & Young LLP (“EY”) as the Company’s independent registered public accounting firm, and EY was dismissed as the Company’s independent registered public accounting firm as of such date. EY served as the Company’s independent registered public accounting firm for the fiscal years ended December 31, 2023 and 2022 and the subsequent periods through April 5, 2024.

Item 9.01 Financial Statements and Exhibits. (d) Exhibits Exhibit No. Description 16.1 Letter from Ernst & Young LLP to the Securities and Exchange Commission dated April 5, 2024 ──────────────────────────────────────────────────────────────────────────────────────────────────────────────── 104 Cover Page Interactive Data File (embedded within the Inline XBRL document) SIGNATURES