Regulation FD Disclosure. On September 1, 2026, Banner Corporation (“Banner”) issued a press release announcing the closing of the merger described below. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference. The information furnished pursuant to this Item and the related exhibits are being “furnished” and will not, except to the extent required by applicable law or regulation, be deemed “filed” by Banner for purposes of Section 18 of the Exch…

Other Events. As previously reported, Banner Corporation (“Banner”) and Pacific Financial Corporation (“Pacific Financial”) entered into that certain Agreement and Plan of Merger, dated as of April 30, 2026 (the “Merger Agreement”), pursuant to which Pacific Financial will merge with and into Banner (the “Merger”). On August 14, 2026, Banner received a letter from the Federal Reserve stating it does not object to Banner’s previously requested waiver of the application requirement for the Merg…

Other Events. As previously reported, Banner Corporation (“Banner”) and Pacific Financial Corporation (“Pacific Financial”) entered into that certain Agreement and Plan of Merger, dated as of April 30, 2026 (the “Merger Agreement”), pursuant to which Pacific Financial will merge with and into Banner (the “Merger”). On August 11, 2026, the Washington State Department of Financial Institutions-Division of Banks granted approval of the Merger subject to approval by the Federal Deposit Insurance…

Other Events. On August 3, 2026, Banner Corporation (“Company”) announced that the Company’s Board of Directors had authorized the repurchase of up to 1.7 million shares of its common stock, or approximately 5% of the Company’s issued and outstanding common stock. The news release announcing the stock repurchase program is attached as Exhibit 99.1 and incorporated by reference herein.

Other Events. On July 22, 2026, Banner Corporation announced its Board of Directors declared a regular quarterly cash dividend on Banner Corporation c ommon stock of $0.52 per share, payable on August 14, 2 026 to stockholders of record as of the close of business on August 4, 2026.

Results of Operations and Financial Condition. * On July 22, 2026, Banner Corporation issued its earnings release for the quarter ended June 30, 2026. A copy of the earnings release is furnished herewith as Exhibit 99.1, and is incorporated herein by reference.

Regulation FD Disclosure. On April 30, 2026, Banner and Pacific Financial issued a joint press release announcing the execution of the Merger Agreement. A copy of the press release is attached to this report as Exhibit 99.1, which is incorporated herein by reference. On April 30, 2026, Banner posted on its investor relations website, https://investor.bannerbank.com, under “Events and Presentations” an investor presentation relating to the Merger. A copy of the investor presentation is attache…

Entry into a Material Definitive Agreement. On April 30, 2026, Banner Corporation, a Washington corporation (“Banner”), entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Pacific Financial Corporation, a Washington corporation (“Pacific Financial”), pursuant to which Pacific Financial will merge with and into Banner (the “Merger”), with Banner as the surviving corporation in the Merger. The Merger Agreement was unanimously approved and adopted by the Board of Directors…

Results of Operations and Financial Condition. * On April 22, 2026, Banner Corporation issued its earnings release for the quarter ended March 31, 2026. A copy of the earnings release is furnished herewith as Exhibit 99.1, and is incorporated herein by reference.

Other Events. On April 22, 2026, Banner Corporation announced its Board of Directors declared a regular quarterly cash dividend on Banner Corporation c ommon stock of $0.52 per share, payable on May 15, 2026 to stockholders of record as of the close of business on May 5, 2026.

Director — Monica B. O'Reilly and Judith A. Steiner: Two new directors were appointed to the Board of Directors.

Results of Operations and Financial Condition. * On January 21, 2026, Banner Corporation issued its earnings release for the quarter and year ended December 31, 2025. A copy of the earnings release is furnished herewith as Exhibit 99.1, and is incorporated herein by reference.

Other Events. On January 21, 2026, Banner Corporation announced its Board of Directors declared a regular quarterly cash dividend on Banner Corporation c ommon stock of $0.50 per share, payable on February 13, 2026 to stockholders of record as of the close of business on February 03, 2026.

Results of Operations and Financial Condition. * On October 15, 2025, Banner Corporation issued its earnings release for the quarter ended September 30, 2025. A copy of the earnings release is furnished herewith as Exhibit 99.1, and is incorporated herein by reference.

Other Events. On October 15, 2025, Banner Corporation announced its Board of Directors declared a regular quarterly cash dividend on Banner Corporation common stock of $0.50 per share, payable on November 14, 2025 to stockholders of record as of the close of business on November 4, 2025.

Director — Millicent Tracey: The filing discloses the routine election of a new independent director to the board, which is a standard governance event rather than an executive departure.

Chief Operating Officer — James M. Costa: The filing discloses the fulfillment of a compensatory award for an internal promotion to Chief Operating Officer, which is a positive signal of retention and advancement rather than a departure.

Other Events. On July 24, 2025, Banner Corporation (“Company”) announced that the Company’s Board of Directors had authorized the repurchase of up to 1,729,199 shares of its common stock, or approximately 5% of the Company’s issued and outstanding common stock. The news release announcing the stock repurchase program is attached as Exhibit 99.1 and incorporated by reference herein.

Results of Operations and Financial Condition. * On July 16, 2025, Banner Corporation issued its earnings release for the quarter ended June 30, 2025. A copy of the earnings release is furnished herewith as Exhibit 99.1, and is incorporated herein by reference.

Other Events. On July 16, 2025, Banner Corporation announced its Board of Directors declared a regular quarterly cash dividend on Banner Corporation common stock of $0.48 per share, payable on August 15, 2025 to stockholders of record as of the close of business on August 5, 2025.

Changes in Registrant's Certifying Accountant On June 9, 2025, Banner Corporation, (the "Company") was notified that Moss Adams LLP ("Moss Adams"), the Company's independent registered public accounting firm, merged with Baker Tilly US, LLP effective on June 3, 2025. The combined audit practices operate as Baker Tilly US, LLP ("Baker Tilly"). In connection with the notification of the merger, Moss Adams has resigned as the auditors of the Company and the Audit Committee of the Company's Board…

Other Events. On April 16, 2025, Banner Corporation announced its Board of Directors declared a regular quarterly cash dividend on Banner Corporation common stock of $0.48 per share, payable on May 9, 2025 to stockholders of record as of the close of business on April 29, 2025.

Results of Operations and Financial Condition. * On April 16, 2025, Banner Corporation issued its earnings release for the quarter ended March 31, 2025. A copy of the earnings release is furnished herewith as Exhibit 99.1, and is incorporated herein by reference.

Results of Operations and Financial Condition. * On January 22, 2025, Banner Corporation issued its earnings release for the quarter ended December 31, 2024. A copy of the earnings release is furnished herewith as Exhibit 99.1, and is incorporated herein by reference.

Other Events. On January 22, 2025, Banner Corporation announced its Board of Directors declared a regular quarterly cash dividend on Banner Corporation common stock of $0.48 per share, payable on February 14, 2025 to stockholders of record as of the close of business on February 4, 2025.