Horizon Technology Finance Corporation

Item 4.01. Changes in Registrant ’ s Certifying Accountant (a) Dismissal of independent registered public accounting firm On May 13, 2026, the Board of Directors (the “Board”) of Horizon Technology Finance Corporation (the “Company”) dismissed RSM US LLP (“RSM”) as the Company’s independent registered public accounting firm. RSM served as the Company’s independent registered public accounting firm since 2008. The audit reports of RSM on the Company’s financial statements for the fiscal years ended December 31, 2024 and December 31, 2025, did not contain an adverse opinion or disclaimer of opinion and were not qualified or modified as to uncertainty, audit scope or accounting principles. During the two most recent fiscal years and through May 13, 2026, there were no disagreements with RSM on any matter of accounting principles or practices, financial statement disclosure or auditing scope or procedure, which disagreements, if not resolved to the satisfaction of RSM, would have caused it to make reference to the subject matter of such disagreements in connection with its reports, nor were there any “reportable events”, as such term is described in Item 304(a)(1)(v) of Regulation S-K promulgated under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). The Company provided RSM with a copy of this Form 8-K prior to its filing with the Securities and Exchange Commission (the “SEC”) and requested that RSM provide the Company with a letter addressed to the SEC stating whether it agrees with the above statements. A copy of RSM’s letter, dated May 14, 2026, is attached as Exhibit 16.1 to this Current Report on Form 8-K. (b) Appointment of new independent registered public accounting firm On May 13, 2026, upon the recommendation of the Audit Committee of the Board, the Board approved the appointment of Grant Thorton LLP (“GT”) to serve as the Company’s independent registered accounting firm to audit the Company’s consolidated financial statements for the fiscal year ended December 31, 2026. During the two most recent fiscal years and through May 13, 2026, the date of the appointment of GT, neither the Company nor any person on its behalf has consulted with GT with respect to either (i) the application of accounting principles to a specified transaction, either completed or proposed, or the type of audit opinion that might be rendered on the Company’s consolidated financial statements or (ii) any matter that was either the subject of a “disagreement” or a “reportable event” as such terms are defined in Items 304(a)(1)(iv) or 304(a)(1)(v), respectively, of Regulation S-K promulgated under the Exchange Act. Item 9.01. Financial Statements and Exhibits. (d) Exhibits: Exhibit Description Number ──────────────────────────────────────────────────────────────────────────────────────────── 16.1 Letter of RSM US LLP, dated May 14, 2026 104 Cover Page Interactive Data File (embedded within the Inline XBRL document)