8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): May 1, 2025

ISABELLA BANK CORPORATION

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (989) 772-9471

Not Applicable

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

| ☐ | Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) | | --- | --- || ☐ | Soliciting material pursuant to Rule l4a-12 under the Exchange Act (17 CFR 240.l4a-l2) | | --- | --- || ☐ | Pre-commencement communications pursuant to Rule l4d-2(b) under the Exchange Act (17 CFR 240.l4d-2(b)) | | --- | --- || ☐ | Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.l3e-4(c)) | | --- | --- |

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Section 8 - Other Events

Item 8.01 Other Events.

On May 1, 2025, Isabella Bank Corporation (the “Company”) issued a press release announcing that its Board of Directors has approved a share repurchase authorization of an additional five hundred thousand (500,000) common shares, pursuant to the Company's publicly announced common stock repurchase plan. Authorizations do not have expiration dates. As common shares are repurchased under this plan, they are retired and revert back to the status of authorized, but unissued common shares.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits:

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 hereunto duly authorized.

INDEX TO EXHIBITS

Document

Exhibit 99.1

Isabella Bank Corporation Announces Increase to Share Repurchase Program

MT. PLEASANT, MICHIGAN — May 1, 2025 — Isabella Bank Corporation (OTCQX:ISBA) (the "Company") announced today that the Board of Directors of the Company approved a resolution to increase its share repurchase program by an additional 500,000 shares, raising the current authorization available under the program to 538,448 shares. The Company has repurchased to date 2,554,126 shares under its share repurchase program since 2007.

The authorization does not have an expiration date. Stock repurchases under the program may be made from time to time as the Company deems appropriate, based on factors such as share price, market conditions, share availability, purchase needs under the Company's employee stock purchase and dividend reinvestment plan, and other relevant factors. There can be no assurance as to the number of shares the Company will purchase, if any, and the program may be modified, renewed, suspended or terminated by the Company at any time without prior notice.

About the Company

Isabella Bank Corporation (OTCQX: ISBA) is the parent holding company of Isabella Bank, a state-chartered community bank headquartered in Mt. Pleasant, Michigan. Isabella Bank was established in 1903 and has been committed to serving its customers' and communities' local banking needs for over 120 years. The Bank offers personal and commercial lending and deposit products, as well as investment, trust, and estate planning services. The Bank has locations throughout eight Mid-Michigan counties: Bay, Clare, Gratiot, Isabella, Mecosta, Midland, Montcalm, and Saginaw.

For more information about Isabella Bank Corporation, visit the Investor Relations link at www.isabellabank.com. Isabella Bank Corporation common stock is quoted on the OTCQX tier of the OTC Markets Group, Inc.’s electronic quotation system (www.otcmarkets.com) under the symbol “ISBA.” The Company’s investor relations firm is Stonegate Capital Partners, Inc. (www.stonegateinc.com).

Contact

Lori Peterson, Director of Marketing

Phone: 989-779-6333 Fax: 989-775-5501