Bank First Corp 10-Q

ITEM 5. OTHER INFORMATION ​ Rule 10b5-1 Trading Arrangements For the quarter ended June 30, 2026, there were no trading arrangements for the sale or purchases of Company securities adopted, terminated or for which the amount, pricing or timing provisions were modified by our directors and officers that was either (1) a contract, instruction or written plan intended to satisfy the affirmative defense conditions of Rule 10b5-1 (c) (a “ Rule 10b5-1 trading arrangement”) or (2) a “ non-Rule 10b5-1 trading arrangement ” (as defined in Item 408(c) of Regulation S-K). ​ ​ 58 Table of Contents ​ ITEM 6. EXHIBITS ​ Exhibit Index ​ Exhibit Number ​ ​ ​ Description ​ ​ ​ 2.1 ​ Agreement and Plan of Merger, dated May 19, 2026, by and between Bank First Corporation and PSB Holdings, Inc. (filed as Exhibit 2.1 to the Company’s Current Report on Form 8-K filed with the SEC on May 19, 2026 and incorporated herein by reference). 10.1 ​ Side Letter Agreement, dated May 19, 2026, by and between Bank First Corporation and PSB Holdings, Inc. (filed as Exhibit 10.1 to the Company’s Current Report on Form 8-K filed with the SEC on May 19, 2026 and incorporated herein by reference). 31.1 ​ Rule 13a-14(a) Certification of Chief Executive Officer* 31.2 ​ Rules 13a-14(a) Certification of Chief Financial Officer* 32.1 ​ Section 1350 Certification of Chief Executive Officer and Chief Financial Officer** 101 INS ​ Inline XBRL Instance Document 101.SCH ​ Inline XBRL Taxonomy Extension Schema Document 101.CAL ​ Inline XBRL Taxonomy Extension Calculation Linkbase Document 101.DEF ​ Inline XBRL Taxonomy Extension Definition Linkbase Document 101.LAB ​ Inline XBRL Taxonomy Extension Label Linkbase Document 101.PRE ​ Inline XBRL Taxonomy Extension Presentation Linkbase Document 104 ​ Cover Page Interactive Data File (the cover page XBRL tags are embedded in the Inline XBRL document) * Filed herewith. ** Furnished herewith. ​ 59 Table of Contents ​ SIGNATURES ​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized. ​ ​ ​ ​ ​ ​ ​ BANK FIRST CORPORATION ​ ​ ​ ​ ​ ​ ​ DATE: August 7, 2026 BY: /s/Kevin M. LeMahieu ​ ​ ​ Kevin M. LeMahieu ​ ​ ​ Chief Financial Officer ​ ​ ​ (Principal Financial and Accounting Officer) ​ ​ ​ 60