ISABELLA BANK CORP

In evaluating an investment in any of our securities, investors should consider carefully, among other things, information under the heading “Forward-Looking Statements” in Part I, Item 2, “Management's Discussion and Analysis of Financial Condition and Results of Operations,” of this Form 10-Q and the risk factors previously disclosed under the heading “Risk Factors” in Part I, Item 1A of our 2025 Annual Report on Form 10-K.

The Corporation is providing these additional risk factors to supplement the risk factors contained in Item 1A. of our Annual Report on Form 10-K for the year ended December 31, 2025. Additional risks and uncertainties not currently known to us or that we currently deem to be immaterial also may materially adversely affect our business, financial condition and/or operating results.

We may face risks with respect to future expansion, including our proposed acquisition of Grand River.

We have entered into the Merger Agreement with Grand River, and we may acquire other financial institutions or parts of those institutions in the future and engage in additional de novo branching. We may also consider and enter into or acquire new lines of business or offer new products or services. As part of our acquisition strategy, we seek companies that are culturally similar to us, have experienced management and are in markets in which we operate or close to those markets so we can achieve economies of scale. We also may receive future inquiries and have discussions with potential acquirers of us or potential companies in which we may engage in a so-called “merger of equals.” Acquisitions and mergers, including our proposed acquisition of Grand River, involve a number of risks, including:

•the time and costs associated with identifying and evaluating potential acquisitions and merger partners;

•inaccurate estimates and judgments regarding credit, operations, management and market risks of the target institution;

•the time and costs of evaluating new markets, hiring experienced local management and opening new offices, and the time lags between these activities and the generation of sufficient assets and deposits to support the costs of the expansion;

•our ability to receive regulatory approvals on the timeline and terms that are acceptable to us;

•the adverse consequences (including applicable termination fees and negative reactions from the financial markets and our customers and employees) we may experience if a merger is terminated under certain circumstances;

•the business uncertainties and contractual restrictions while a merger is pending;

•the limitation on our ability to pursue alternative acquisitions and mergers and the hindrance of other companies’ interest in trying to acquire us;

•our ability to manage the expanded business and operations post-merger;

•entry into new markets where we lack experience;

•the strain of growth on our infrastructure, staff, internal controls and management, which may require additional personnel, time and expenditures;

•the introduction of new products and services into our business;

•the possibility of unknown or contingent liabilities;

•the risk of loss of key employees and customers; and

•fluctuations in the market price of our common stock pre- and post-merger.

We also face litigation risks with respect to potential mergers and acquisitions, and such litigation is common.

We expect to continue to evaluate merger and acquisition opportunities that are presented to us in our current and expected markets and conduct due diligence related to those opportunities, as well as negotiate to acquire or merge with other institutions. If we announce a transaction, we may issue equity securities, including common stock and securities convertible into shares of our common stock in connection with future acquisitions. As a result, holders of our common stock may have a reduced ownership and voting interest in the Corporation after a transaction and may exercise less influence over management.

We also may issue debt to finance one or more transactions, including subordinated debt issuances. Generally, acquisitions of financial institutions involve the payment of a premium over book and market values, resulting in dilution of our book value and fully diluted earnings per share, as well as dilution to our existing shareholders. We may incur substantial costs to expand, and we can give no assurance such expansion will result in the levels of profits we seek. There is no assurance that, following any future mergers or acquisitions, including our proposed acquisition of Grand River, that our integration efforts will be successful or that the Corporation, after giving effect to the acquisition, will achieve increased revenues, and failure to realize such expected revenue increases, cost savings, increases in market presence or other benefits could have a material adverse effect on our financial conditions and results of operations.

We may not be able to successfully integrate Grand River or to realize the anticipated benefits of the merger with Grand River.

We entered into the Merger Agreement with Grand River on June 11, 2026. If the proposed acquisition of Grand River is completed, we will also integrate the systems and operations of Grand River.

A successful integration of Grand River’s operations with our operations so that the Corporation operates as one entity depends substantially on our ability to successfully consolidate operations, management teams, corporate cultures, systems and procedures and to eliminate redundancies and costs. While we have substantial experience in successfully integrating institutions we have acquired, we may encounter difficulties during integration, such as:

•the loss of key employees and customers;

•the disruption of operations and businesses;

•inability to maintain and increase competitive presence;

•loan, deposit, and revenue attrition;

•inconsistencies in standards, control procedures and policies;

•unexpected issues with costs, operations, personnel, and technology; and

•problems with the assimilation of new operations, sites or personnel.

Integration activities could divert resources from regular operations. In addition, general market and economic conditions, governmental actions, natural and human disasters or other international or domestic calamities affecting the financial industry generally may inhibit the Corporation’s successful integration of Grand River.

In addition, we have proposed to acquire Grand River with the expectation that this merger will result in various benefits including, among other things, benefits relating to enhanced revenues, a strengthened and expanded market position for the combined company, technology efficiencies, cost savings and operating efficiencies. Achieving the anticipated benefits of these mergers is subject to a number of uncertainties, including whether we integrate the institution in an efficient and effective manner, and general competitive factors in the marketplace. Failure to achieve these anticipated benefits could result in a reduction in the price of our shares as well as in increased costs, decreases in the amount of expected revenues and diversion of management's time and energy and could materially and adversely affect the Corporation’s financial condition, results of operations, business and prospects.