Isabella Bank reported net income of $6.61 million

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For the quarterly period ended June September 30, 2026

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The number of common shares outstanding of the registrant s Common Stock (no par value) was 7,628,873 7,651,045 as of August 6, October 28, 2026.

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Financial statements 775 changes

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(dollars in thousands) June September 30,

Cash and cash equivalents $ 41,774 138,540 $ 26,041

Marketable securities AFS (amortized cost of $ 450,111 431,257 and $ 507,689 , respectively)

Mortgage loans HFS 410 303 423

Loans held for investment 1,589,672 1,535,808 1,536,364

Allowance for credit losses ( 14,479 14,398 ) ( 13,727 )

Loans, net 1,575,193 1,521,410 1,522,637

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Premises and equipment 28,894 28,858 29,000

Cash surrender value of BOLI 46,603 51,253 46,133

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Other assets 33,596 33,541

Other assets 36,728 33,541

Total assets $ 2,219,641 2,240,515 $ 2,209,448

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Savings 300,867 280,429

Noninterest bearing demand deposits $ 414,018 409,729 $ 426,342

Interest bearing demand deposits 252,149 254,116 266,187

Money market deposits 453,478 578,454 436,631

Savings 291,508 280,429

Certificates of deposit 389,401 358,801 410,065

Total deposits 1,809,913 1,892,608 1,819,654

Short-term borrowings 116,012 57,874 68,000

1 unchanged paragraph

Other liabilities 15,453 15,884

Retained earnings 119,844 113,849

Subordinated debt, net of unamortized issuance costs 29,559 29,581 29,514

Other liabilities 14,867 15,884

Total liabilities 1,970,937 1,994,930 1,978,052

Common stock no par value, 15,000,000 shares authorized: issued and outstanding 7,628,809 7,653,498 shares at June September 30, 2026 and 7,322,207 shares at December 31, 2025

Shares to be issued for deferred compensation obligations 2,532 2,494 2,366

Retained earnings 124,341 113,849

Accumulated other comprehensive loss ( 8,751 17,365 ) ( 8,023 )

Total shareholders equity 248,704 245,585 231,396

Total liabilities and shareholders equity $ 2,219,641 2,240,515 $ 2,209,448

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June 30 Six Months Ended

September 30 Nine Months Ended

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Loans, including fees $ 22,607 $ 19,832 $ 44,071 $ 39,180

Taxable 2,902 2,513 5,391 4,616

Nontaxable 470 519 969 1,059

FHLB stock 64 125 139 285

Federal funds sold and other 173 253 775 735

Total interest income 26,216 23,242 51,345 45,875

Deposits 6,778 7,391 13,890 14,854

Short-term borrowings 1,007 324 1,743 665

Subordinated debt 304 266 570 532

Total interest expense 8,132 8,113 16,379 16,221

Net interest income 18,084 15,129 34,966 29,654

Provision for (reversal of) credit losses 895 ( 1,099 ) 1,499 ( 1,206 )

Service charges and fees 2,440 1,936 4,717 3,810

Wealth management fees 1,216 1,084 2,324 2,063

Other 270 319 765 592

Total noninterest income 4,375 3,686 8,736 7,214

Loans, including fees $ 22,986 $ 20,583 $ 67,057 $ 59,763

Taxable 2,939 2,478 8,330 7,094

Nontaxable 452 516 1,421 1,575

FHLB stock 58 70 197 355

Federal funds sold and other 1,082 1,235 1,857 1,970

Total interest income 27,517 24,882 78,862 70,757

Deposits 6,835 8,012 20,725 22,866

Short-term borrowings 806 441 2,549 1,106

FHLB advances 43 132 176 170

Subordinated debt 503 267 1,073 799

Total interest expense 8,144 8,720 24,523 24,941

Net interest income 19,373 16,162 54,339 45,816

Provision for (reversal of) credit losses 50 209 1,549 ( 997 )

Net interest income after provision for credit losses 17,189 16,228 33,467 30,860 19,323 15,953 52,790 46,813

Service charges and fees 2,429 2,227 7,146 6,037

Wealth management fees 1,168 1,074 3,492 3,137

Increase in the cash surrender value of BOLI 434 300 882 672 478 468 1,360 1,140

Net gain on sale of mortgage loans 15 47 48 77 65 38 113 115

Other 426 501 1,191 1,093

Total noninterest income 4,566 4,308 13,302 11,522

1 unchanged paragraph

Compensation and benefits 8,147 7,496 16,075 14,879

Occupancy and equipment 2,890 2,650 5,730 5,250

Other professional services 807 863 1,822 1,574

ATM and debit card fees 629 555 1,187 1,041

Marketing 514 469 1,020 928

FDIC insurance premiums 288 267 594 570

Merger-related expenses 505 505

Other 1,606 1,445 3,115 2,802

Total noninterest expenses 15,386 13,745 30,048 27,044

Income before income tax expense 6,178 6,169 12,155 11,030

Income tax expense 1,137 1,138 2,122 2,050

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and 695 more changes in the filing

MD&A 4 changes

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Upon the terms and subject to the conditions of the Merger Agreement, at the effective time of the Merger, each voting and non-voting share of common stock of Grand River issued and outstanding immediately prior to the Effective Time, other than certain shares held by Grand River or the Corporation or dissenting shares, will be converted into the right to receive, at the election of the holder thereof, and subject to adjustment and proration, as applicable, (i) an amount of cash equal to the quotient of (A) $18,262,391, divided by (B) the product obtained by multiplying (x) the number of shares of Grand River Common Stock issued and outstanding as of the Effective Time by (y) 0.35, rounded to the nearest cent, or (ii) the number of shares of common stock of the Corporation, no par value, multiplied by the Exchange Ratio.

The Exchange Ratio is defined in the Merger Agreement as a number, as adjusted, of shares of Isabella Common Stock equal to the quotient of (A) 839,003 shares of Isabella Common Stock, divided by (B) the difference of (1) the aggregate number of shares of Grand River Common Stock issued and outstanding immediately prior to the Effective Time, other than certain shares held by Grand River or the Corporation or dissenting shares, minus (2) the Cash Conversion Number, rounded to the nearest ten thousandth.

Merger Consideration elections by Grand River shareholders will be subject to proration procedures whereby 65% of the shares of Grand River Common Stock will be exchanged for the Per Share Stock Consideration and 35% of the shares of Grand River common stock will be exchanged for the Per Share Cash Consideration. Based on the assumption of 9,136,529 shares of Grand River Common Stock issued and outstanding as of the Effective Time, the Per Share Cash Consideration to be paid is estimated to be approximately $5.71 and the Exchange Ratio is estimated to be approximately 0.1413. At March 31, 2026, Grand River had approximately $511.7 million in total assets, $433.0 million in total loans and $438.9 million in total deposits. The pro forma company is projected to have approximately $2.7 billion in total assets.

As previously disclosed, on June 11, 2026, the Corporation, 401 Merger Sub, Inc., a Michigan corporation and a wholly owned subsidiary of the Corporation ( Merger Sub ), and Grand River Commerce, Inc. ( Grand River ), entered into an Agreement and Plan of Merger (the Merger Agreement provides that, upon the terms and subject to ), providing for the conditions set forth therein, merger of Merger Sub will merge with and into Grand River, with Grand River as the surviving entity, and immediately following followed by the merger of Grand River will merge with and into the Corporation, with the Corporation as the surviving entity. The Merger Agreement further provides that immediately following the Second Step Merger, Grand River Bank, a Michigan state-chartered member bank and wholly owned subsidiary of Grand River, will merge with and into the Bank, with the Bank as the surviving bank. We expect to complete the Merger in the fourth quarter of 2026, subject Refer to satisfaction of closing conditions, including receipt of customary required regulatory approvals and the approval of the Agreement by the shareholders of Grand River. Note 9 above for additional information.

Forward-looking statements 225 changes

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risks related to rising interest rates;

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risks relating to the proposed Merger including, without limitation: the timing of consummation of the proposed transaction between the Corporation and Grand River; the risk that any condition to closing of the proposed Merger may not be satisfied or waived; the risk that the Merger may not be completed at all; the diversion of management time on issues related to the proposed Merger; the expected impact of the proposed Merger and on the combined entities operations, financial condition, and financial results; the businesses of Corporation and Grand River may not be combined successfully, or such combination may take longer to accomplish than expected; the cost savings from the proposed Merger may not be fully realized or may take longer to realize than expected; operating costs, customer loss and business disruption following the proposed Merger, including adverse effects on relationships with employees, may be greater than expected; the risk of deposit and customer attrition; and increased competitive pressures on solicitations of customers by competitors; regulatory approvals of the proposed Merger may not be obtained, or adverse conditions may be imposed in connection with regulatory approvals of the proposed Merger; and the risk that the Grand River shareholders may not approve the proposed Merger;

22 unchanged paragraphs

The provision for credit losses was $895,000 for the three months ended June 30, 2026, driven by a $465,000 increase in the ACL on loans and net charge offs totaling $384,000. The provision for credit losses for the three months ended June 30, 2025 was a credit of $1.1 million, which reflects $1.4 million in net recoveries, offset by a $242,000 increase in the ACL on loans and an increase in the reserve for unfunded commitments. Recoveries of $1.6 million during second quarter 2025 were related to overdrawn deposit accounts from a single customer that were charged off during the third quarter of 2024.

Financial Condition (June (September 30, 2026 to December 31, 2025 comparison)

Total assets increased $10.2 $31.1 million, or 0.5%, 1.4%, to $2.2 billion as of June September 30, 2026. This increase was primarily due to an increase of $53.3 million in loans and an increase of $15.7 $112.5 million in cash and cash equivalents, These increases were offset by a $58.5 an $88.3 million decline in AFS securities.

The AFS securities portfolio decreased $58.5 $88.3 million, or 11.8%, 17.7%, to $439.3 $409.5 million as of June September 30, 2026. The decrease was a result of maturities and principal paydowns of $121.8 $177.1 million, offset by $64.4 $100.7 million in purchases. Net unrealized losses on AFS securities were $10.8 $21.7 million as of June September 30, 2026, compared to $9.9 million at December 31, 2025. Net unrealized losses as a percentage of the amortized cost of AFS securities were consistent increased to 5.0%, compared to 1.9% at December 31, 2025. at 2%.

Loans increased $53.3 million, or 3.5%, decreased $556,000 to $1.6 $1.5 billion as of June September 30, 2026. primarily by growth in The commercial real estate and residential real estate loan portfolios grew $29.9 million and $29.7 million, respectively, but were offset by declines in advances to mortgage brokers and consumer loans of $33.5 $39.0 million and $22.1 $10.6 million, respectively. Most residential originations were adjustable rate adjustable-rate products, which are retained on the balance sheet rather than sold in the secondary market. The consumer loan portfolio continues to decrease amid declining demand, continued competition, and our disciplined adherence to credit quality standards.

The ACL increased $752,000, $671,000, or 5.5%, 4.9%, to $14.5 $14.4 million as of June September 30, 2026. The increase is due to commercial and residential real estate loan growth and an increase in loss rates driven by loans charged off during the year. Nonaccrual loans were $7.8 $7.5 million as of June September 30, 2026 compared to $4.6 million at December 31, 2025. Past due and accruing accounts between 30 to 89 days as a percentage of total loans was 0.06% 0.10% at June September 30, 2026, compared to 0.44% at year-end 2025.

Total deposits decreased $9.7 increased $73.0 million, or 0.5%, 4.0%, to $1.8 $1.9 billion as of June September 30, 2026. The decline increase was a result of a $20.7 $141.8 million increase in money market accounts and a $11.1 million increase in savings deposits. These increases were offset by a $51.3 million decline in certificates of deposit, a $14.0 $16.6 million decline in interest noninterest bearing demand deposits, and a $12.3 $12.1 million decline in noninterest interest bearing demand deposits. These declines were offset by a $20.4 million increase in savings deposits and a $16.8 million increase in money market accounts.

Total equity was $248.7 $245.6 million, or $32.60 $32.09 per share, at June September 30, 2026 compared to $231.4 million, or $31.60 per share, as of December 31, 2025. The increase in total equity is primarily due to the issuance of 303,371 322,685 shares of common stock as part of the previously announced Corporation s ongoing at-the-market stock offering, increasing total equity by $11.7 $12.5 million, net of estimated offering-related expenses. Tangible book value per share (non-GAAP) was $26.27 $25.78 as of June September 30, 2026, compared to $25.01 as of December 31, 2025. Net unrealized losses in the AFS securities portfolio reduced tangible book value per share (non-GAAP) by $1.14 $2.26 and $1.09 for the respective periods.

As of June September 30, 2026, we had $754.8 $850.5 million of unencumbered sources of liquidity and strong consolidated capital ratios. The Tier 1 Leverage Ratio was 9.59%, 9.71%, Tier 1 risk-based capital was 12.34%, 12.96%, and Total risk-based capital was 14.63%. 15.29%.

Comparison of Operating Results for the three and six nine months ended June September 30, 2026, and 2025, unless otherwise noted

Net income for the three months ended June September 30, 2026 was $5.0 $6.6 million, or $0.69 $0.86 per diluted share, compared with $5.0 $5.2 million, or $0.68 $0.71 per diluted share, for the three months ended June September 30, 2025. Net income for the six nine months ended June September 30, 2026 was $10.0 $16.6 million, or $1.37 $2.24 per diluted share, compared with $9.0 $14.2 million, or $1.21 $1.92 per diluted share, for the six nine months ended June September 30, 2025.

Net interest income was $18.1 $19.4 million for the three months ended June September 30, 2026 and $15.1 $16.2 million for the three months ended June September 30, 2025, representing 3.54% 3.71% and 3.14% 3.15% of interest earning assets, or NIM on an a FTE basis (non-GAAP), respectively. The book yield from securities was 2.82% 3.20% and 2.38% 2.42% for the three months ended June September 30, 2026 and 2025, respectively. The yield on loans increased to 5.86% 5.95% for the three months ended June September 30, 2026 from 5.71% 5.78% for the three months ended June September 30, 2025. The increase in loan yields was primarily due to higher rates on new loans and variable rate commercial loans that continue to reprice. The cost of interest-bearing liabilities for the three months ended June September 30, 2026 decreased to 2.09% 2.08% from 2.24% 2.25% for the three months ended June September 30, 2025 primarily due to lower rates on money market and certificate of deposit products.

Net interest income was $35.0 $54.3 million for the six nine months ended June September 30, 2026 and $29.7 $45.8 million for the six nine months ended June September 30, 2025, representing 3.43% 3.53% and 3.10% 3.12% of earning assets, or NIM on an a FTE basis (non-GAAP), respectively. The book yield from securities was 2.67% 2.83% and 2.31% 2.34% for the six nine months ended June September 30, 2026 and 2025, respectively. The yield on loans increased to 5.82% 5.88% for the six nine months ended June September 30, 2026 from 5.72% 5.75% for the six nine months ended June September 30, 2025. The increase in loan yields was primarily due to higher rates on new loans and variable rate commercial loans that continue to reprice. The cost of interest-bearing liabilities for the six nine months ended June September 30, 2026 decreased to 2.12% 2.10% from 2.25% for the six nine months ended June September 30, 2025, primarily due to lower rates on money market and certificate of deposit products.

The provision for credit losses was $50,000 for the three months ended September 30, 2026, as a result of net charge offs totaling $207,000, offset by an $81,000 decrease in the ACL on loans and a decrease in the reserve for unfunded commitments. The provision for credit losses for the three months ended September 30, 2025 was $209,000, which reflects a $172,000 increase in the ACL and net charge offs totaling $74,000, offset by a decrease in the reserve for unfunded commitments.

The provision for credit losses was $1.5 million for the six nine months ended June September 30, 2026, as compared to a credit of $1.2 million $997,000 for the six nine months ended June September 30, 2025. Net charge offs for the six nine months ended June September 30, 2026 totaled $637,000, $844,000, while there were net recoveries of $1.5 $1.4 million for the six nine months ended June September 30, 2025.

Noninterest income for the three months ended June September 30, 2026 and 2025 was $4.4 $4.6 million and $3.7 $4.3 million, respectively. Service charges and fees increased $504,000 as a result of internal initiatives designed to align our fees with the market. Earnings on BOLI policies increased $134,000 compared to second quarter 2025 due to additional investments in a separate account BOLI in 2025. $202,000 and wealth management fees grew $132,000 increased $94,000 due to growth in assets under management since second quarter 2025.

Noninterest income for the six nine months ended June September 30, 2026 and 2025 was $8.7 $13.3 million and $7.2 $11.5 million, respectively. Service charges and fees increased $907,000 as a result of internal initiatives designed to align our fees with the market. $1.1 million, wealth management fees grew $261,000 increased $355,000 due to growth in assets under management, and earnings on BOLI policies increased $210,000 $220,000 due to additional investments in a separate account BOLI. in 2025. Other noninterest income in 2026 includes a included gains of $137,000 gain and $163,000 related to a death benefit benefits from a BOLI policy. policies for the nine months ended September 30, 2026 and 2025, respectively.

Noninterest expenses for the three months ended June September 30, 2026 and 2025 were $15.4 $15.6 million and $13.7 $14.0 million, respectively. Compensation and benefit expenses increased $651,000, $867,000, reflecting annual merit increases, incentives, and higher medical insurance claims. Occupancy and equipment increased $240,000 $156,000 and merger-related expenses of $505,000 were included in noninterest expenses in second quarter 2026. $672,000.

Noninterest expenses for the six nine months ended June September 30, 2026 and 2025 were $30.0 $45.7 million and $27.0 $41.0 million, respectively. Compensation and benefit expenses increased $1.2 $2.1 million for the same reasons as the quarterly comparison. Occupancy and equipment expenses increased $480,000 $636,000 and merger-related expenses during second quarter 2026 totaled $505,000. were $1.2 million.

Income tax expense for both of the three months ended June September 30, 2026 and 2025 was $1.1 $1.6 million while and $1.0 million, respectively. The ETR was 18% for both the same periods was 20% and 17%, respectively. Income tax expense for both of the six nine months ended June September 30, 2026 and 2025 was $2.1 $3.8 million while and $3.1 million, respectively. The ETR was 17% 18% for both the six nine months ended June September 30, 2026 and 19% for 2025. The six ETR in the first nine months ended June 30, 2025. of 2026 included the impact of certain non-deductible merger-related expenses. The ETR in the first six nine months of 2025 included a one-time tax expense totaling $166,000 due related to the taxes owed from the lifetime earnings on BOLI policies that were surrendered. during first quarter 2025. Excluding the one-time charge, the ETR was 17% for the first six months of 2025.

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Tangible book value (1) (2)

Three Months Ended Six Nine Months Ended

(dollars in thousands, except per share amounts) June September 30,

Basic earnings $ 0.86 $ 0.69 $ 0.68 $ 0.64 $ 0.71 $ 0.68 $ 1.37 2.24 $ 1.21 1.93

Diluted earnings 0.86 0.69 0.68 0.64 0.71 0.68 1.37 1.21 2.24 1.92

Dividends 0.28 0.28 0.28 0.28 0.28 0.56 0.56 0.84 0.84

Return on average total assets 1.17 % 0.91 % 0.91 % 0.85 % 0.94 % 0.96 % 0.91 1.00 % 0.87 0.89 %

Return on average shareholders equity 10.43 % 8.50 % 8.58 % 8.04 % 9.28 % 9.19 % 8.54 9.20 % 8.35 8.67 %

1 unchanged paragraph

Net interest margin yield (FTE) 3.71 % 3.54 % 3.33 % 3.28 % 3.15 % 3.14 % 3.43 3.53 % 3.10 3.12 %

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Tangible shareholders equity to tangible assets (1) (2)

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Net income 6,605 5,041 4,992 4,690 5,240 5,031 10,033 8,980 16,638 14,220

Interest income 27,517 26,216 25,129 25,278 24,882 23,242 51,345 45,875 78,862 70,757

Interest expense 8,144 8,132 8,247 8,550 8,720 8,113 16,379 16,221 24,523 24,941

Net interest income 19,373 18,084 16,882 16,728 16,162 15,129 34,966 29,654 54,339 45,816

Provision for (reversal of) credit losses 50 895 604 434 209 (1,099) 1,499 (1,206) 1,549 (997)

Noninterest income 4,566 4,375 4,361 4,444 4,308 3,686 8,736 7,214 13,302 11,522

Noninterest expenses 15,648 15,386 14,662 13,921 13,985 13,745 30,048 27,044 45,696 41,029 (1) At end of period.

3 unchanged paragraphs

June September 30, 2026 March 31, 2026 June 30, 2026 September 30, 2025

2 unchanged paragraphs

Taxable 432,520 2,902 2.69 % 430,376 2,489 2.35 % 461,483 2,513 2.18 %

Federal funds sold 2 3.67 % 7 3.54 % 6 3.83 %

Taxable 378,202 2,939 3.08 % 432,520 2,902 2.69 % 448,112 2,478 2.19 %

FHLB stock 5,600 64 4.55 58 4.18 % 5,600 75 5.36 64 4.55 % 5,600 125 8.94 70 4.95 %

Federal funds sold 3 3.91 % 2 3.67 % 186 2 4.35 %

1 unchanged paragraph

Premises and equipment 29,086 29,110 28,306

Other assets 116,913 116,639 106,595

Allowance for credit losses (14,471) (14,078) (13,680) (13,369) (13,057)

Cash and demand deposits due from banks 24,854 22,544 23,113 22,026 25,591

Premises and equipment 28,802 29,086 28,313

Other assets 120,411 116,913 109,692

Total assets $ 2,218,596 2,246,818 $ 2,224,887 2,218,596 $ 2,092,687 2,206,722

1 unchanged paragraph

Interest bearing demand deposits $ 257,088 205 0.32 % $ 266,101 294 0.45 % $ 236,076 220 0.37 %

Money market deposits 452,737 2,625 2.33 % 464,438 2,719 2.37 % 449,110 2,857 2.55 %

Savings 302,375 503 0.67 % 291,413 488 0.68 % 286,434 544 0.76 %

Certificates of deposit 396,481 3,445 3.49 % 407,483 3,611 3.59 % 395,450 3,770 3.82 %

Short-term borrowings 115,713 1,007 3.49 % 86,885 736 3.44 % 41,661 324 3.11 %

FHLB advances 4,396 43 3.86 % 13,444 133 3.96 % 11,539 132 4.53 %

Interest bearing demand deposits $ 264,269 199 0.30 % $ 257,088 205 0.32 % $ 234,105 144 0.24 %

Money market deposits 503,054 3,030 2.39 % 452,737 2,625 2.33 % 534,127 3,533 2.63 %

Savings 288,515 456 0.63 % 302,375 503 0.67 % 289,442 560 0.77 %

Certificates of deposit 374,370 3,150 3.34 % 396,481 3,445 3.49 % 399,781 3,775 3.75 %

Short-term borrowings 94,938 806 3.37 % 115,713 1,007 3.49 % 52,700 441 3.32 %

FHLB advances 0.00 % 4,396 43 3.86 % 0.00 %

1 unchanged paragraph

Total interest bearing liabilities 1,558,335 8,132 2.09 % 1,559,286 8,247 2.14 % 1,449,725 8,113 2.24 %

Total interest bearing liabilities 1,554,713 8,144 2.08 % 1,558,335 8,132 2.09 % 1,539,632 8,720 2.25 %

1 unchanged paragraph

Demand deposits 404,805 411,011 409,262

Other liabilities 17,462 18,653 14,158

Shareholders equity 237,994 235,937 219,542

Demand deposits 420,649 404,805 428,144

Other liabilities 20,103 17,462 14,976

Shareholders equity 251,353 237,994 223,970

Total liabilities and shareholders equity $ 2,218,596 2,246,818 $ 2,224,887 2,218,596 $ 2,092,687 2,206,722

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(3) Includes FTE adjustments of $126,000, $130,000, $138,000, and $178,000, $144,000, respectively.

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June September 30, 2026 June September 30, 2025

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Taxable 431,452 5,391 2.52 % 449,919 4,616 2.07 %

Nontaxable 65,731 1,237 3.80 % 74,551 1,421 3.84 %

FHLB stock 5,600 139 4.95 % 8,291 285 6.89 %

Federal funds sold 5 3.57 % 5 4.03 %

Taxable 413,508 8,330 2.69 % 449,310 7,094 2.11 %

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Controls and procedures 1 change

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We carried out an evaluation, under the supervision and with the participation of the Principal Executive Officer and Principal Financial Officer, of the effectiveness of the design and operation of our disclosure controls and procedures (as such term is defined in Rules 13a-15(e) and 15(d)-15(e) under the Exchange Act) as of June September 30, 2026, pursuant to Exchange Act Rule 13a-15. Based upon that evaluation, the Principal Executive Officer and Principal Financial Officer concluded that our disclosure controls and procedures as of June September 30, 2026, were effective to ensure that information required to be disclosed in reports that we file or submit under the Exchange Act are recorded, processed, summarized and reported within the time periods specified in SEC rules and forms.

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Risk factors 36 changes

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. Management believes there have been no material changes in the risk factors disclosed by the Corporation in Part I, Item 1A, Risk Factors, of the 2025 Annual Report on Form 10-K. 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.

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 finance an acquisition and possible dilution to our existing shareholders;

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

the diversion of our management s attention to the negotiation of a transaction, and the integration of the operations and personnel of the combining businesses;

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;

exposure to potential asset quality issues with acquired institutions;

the introduction of new products and services into our business;

the possibility of unknown or contingent liabilities;

the incurrence and possible impairment of goodwill associated with an acquisition and possible adverse short-term effects on our results of operations;

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.

Unregistered sales of stock 10 changes

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The following table provides information for the three-month three month period ended June September 30, 2026, with respect to our common stock repurchase plan:

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March 31, 2026 453,210

April 1 - 30 1,810 $ 48.07 1,810 451,400

May 1 - 31 1,423 41.46 1,423 449,977

June 1 - 30 1,871 41.15 1,871 448,106

June 30, 2026 5,104 $ 43.69 5,104 448,106

July 1 - 31 989 $ 39.43 989 447,117

August 1 - 31 1,246 40.13 1,246 445,871

September 1 - 30 1,199 39.20 1,199 444,672

September 30, 2026 3,434 $ 39.60 3,434 444,672

Other information 1 change

1 unchanged paragraph

During the fiscal quarter ended June September 30, 2026, none of the Corporation s directors or officers adopted , modified or terminated a Rule 10b5-1 trading arrangement or a non-Rule 10b5-1 trading arrangement, in each case as defined in Item 408 of Regulation S-K.

Exhibits 5 changes

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Participation Agreement, dated August 11, 2026, by and between Isabella Bank Corporation and Gerald J. Ritzert (10)

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* Management Contract or Compensatory Plan or Arrangement.

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(10) Previously filed as an Exhibit to the Isabella Bank Corporation Form 8-K, filed August 14, 2026, and incorporated herein by reference.

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Date: August 10, October 30, 2026 /s/ Jerome E. Schwind

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Date: August 10, October 30, 2026 /s/ Gerald J. Ritzert

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