Exhibit 99.1

Mercantile Bank Corporation Announces Robust Third Quarter 2026 Results

Net interest income growth, loan portfolio expansion, strong local deposit generation, and continued strength in asset quality metrics and capital levels highlight the quarter

GRAND RAPIDS, Mich., October 20, 2026 – Mercantile Bank Corporation (NASDAQ: MBWM) ("Mercantile") reported net income of $24.1 million, or $1.39 per diluted share, for the third quarter of 2026, compared with net income of $23.8 million, or $1.46 per diluted share, for the third quarter of 2025.  Net income during the first nine months of 2026 totaled $72.7 million, or $4.21 per diluted share, compared with net income of $65.9 million, or $4.06 per diluted share, during the first nine months of 2025.  Excluding non-recurring costs associated with the acquisition of Eastern Michigan Financial Corporation and core and digital banking system conversion and the impacts of other one-time items (non-GAAP measurements), adjusted net income was $24.5 million, or $1.42 per diluted share, for the third quarter of 2026, $24.3 million, or $1.50 per diluted share, for the third quarter of 2025, $76.1 million, or $4.41 per diluted share, for the first nine months of 2026, and $66.4 million, or $4.09 per diluted share, for the first nine months of 2025.  Using these non-GAAP measures, adjusted earnings per diluted share increased $0.32, or 7.8 percent, in the first nine months of 2026 compared to the respective 2025 period.

“Our financial performance metrics remained strong during the third quarter of 2026,” said Ray Reitsma, President and Chief Executive Officer of Mercantile.  “The robust operating results were fueled by net interest income expansion, reflecting solid earning asset growth and a higher net interest margin, a significant increase in treasury management fees, strong local deposit growth, a relatively low level of provision expense stemming from ongoing strength in asset quality measures, and the maintenance of a sound regulatory capital profile.  As evidenced by the growth in the loan and local deposit portfolios, our team members have continued to meet the needs of existing customers and secure new client relationships.  At the same time, we have devoted significant efforts and resources on core and digital banking system conversion-related activities to ensure a smooth transition that is expected to occur in the first quarter of 2027, which we believe will provide for a superior experience and a more durable platform for us and our customers.  The notable net growth in local deposits provided for a further reduction in our loan-to-deposit ratio.  We believe ample opportunities are available to us to expand our presence in Southeast Michigan, and as such, we have made meaningful investments in talented individuals to serve that area and gain market share.”  

Third quarter highlights include:

Operating Results

Net revenue, consisting of net interest income and noninterest income, was $73.2 million during the third quarter of 2026, an increase of $10.8 million, or 17.3 percent, from $62.4 million during the prior-year third quarter.  Net interest income during the third quarter of 2026 was $60.9 million, up $8.9 million, or 17.1 percent, from $52.0 million during the respective 2025 period mainly due to growth in earning assets and a higher net interest margin.  Eastern Michigan Bank’s net interest income totaled $5.8 million during the third quarter of 2026.  Noninterest income totaled $12.3 million during the current-year third quarter, up $1.9 million, or 18.4 percent, from $10.4 million during the third quarter of 2025 primarily due to increases in treasury management fees, interest rate swap income, and mortgage banking income.  Eastern Michigan Bank generated $0.5 million in noninterest income during the third quarter of 2026, mainly consisting of deposit service charges.

The net interest margin was 3.73 percent in the third quarter of 2026, up from 3.49 percent in the prior-year third quarter.  The yield on average earning assets was 5.52 percent during the third quarter of 2026, a decrease from 5.74 percent during the respective 2025 period.  The lower yield largely resulted from a reduced yield on loans, which more than offset an improved yield on securities resulting from the reinvestment of relatively low-yielding bonds and investment portfolio expansion activities, along with the positive impact stemming from the addition of Eastern Michigan Bank’s securities portfolio.  The yield on loans was 6.12 percent during the third quarter of 2026, down from 6.35 percent during the third quarter of 2025, mainly due to lower interest rates on variable-rate commercial loans resulting from the Federal Open Market Committee (“FOMC”) reducing the targeted federal funds rate.  The FOMC decreased the targeted federal funds rate by 25 basis points in each of September, October, and December of 2025, during which time average variable-rate commercial loans represented approximately 77 percent of average total commercial loans.  The yield on securities equaled 3.43 percent during the third quarter of 2026, up from 2.90 percent during the prior-year third quarter.  A change in earning asset mix, consisting of a decrease in higher-yielding loans as a percentage of earning assets and an increase in relatively lower-yielding securities as a percentage of earning assets and reflecting a strategic initiative to reduce the loan-to-deposit ratio and the onboarding of Eastern Michigan Bank’s liquid balance sheet, and a lower yield on other interest-earning assets, reflecting the aforementioned decreased interest rate environment, negatively impacted the yield on average earning assets during the third quarter of 2026.

During the third quarter of 2026, the cost of funds was 1.79 percent, down from 2.25 percent during the third quarter of 2025, primarily due to lower rates paid on money market accounts and time deposits, reflecting the decreased interest rate environment.  An increase in low-cost deposit products as a percentage of total funding sources, mainly resulting from the addition of Eastern Michigan Bank’s deposit base and successful client acquisition efforts, also contributed to the reduced cost of funds.  Furthermore, the expansion of existing deposit relationships and a reduction in brokered deposits positively impacted the cost of funds during the third quarter of 2026.  The latter reflects a strategy to refine the deposit base whereby the brokered deposit market will be accessed on a limited basis and reliance on other higher-priced deposit relationships will be lessened.

Mercantile recorded provisions for credit losses of $0.7 million and $0.2 million during the third quarters of 2026 and 2025, respectively.  The provision expense recorded during the current-year third quarter primarily reflected increases in specific and qualitative factor allocations of $1.7 million and $0.7 million, respectively, along with allocations of $0.6 million necessitated by net loan growth.  These factors were partially offset by decreases in the required reserve of $1.5 million and $0.7 million stemming from an increase in residential mortgage and consumer loan prepayment speeds and a decline in baseline loss allocations, respectively.  The recording of net loan recoveries and ongoing strength in loan quality metrics during both periods positively impacted necessary provision levels.

Noninterest income totaled $12.3 million during the third quarter of 2026, up $1.9 million, or 18.4 percent, from $10.4 million during the prior-year third quarter.  The increase primarily stemmed from growth in treasury management fees, interest rate swap income, and mortgage banking income.  The rise in treasury management fees largely resulted from new commercial customer acquisitions and clients’ expanded use of products and services.  The growth in interest rate swap income, which can vary from period to period due to the timing of closing transactions, mainly reflected a higher volume of new swap transactions.

Noninterest expense totaled $43.6 million during the third quarter of 2026, compared to $34.8 million during the third quarter of 2025.  Costs related to the core and digital banking system conversion aggregated $0.4 million during the third quarter of 2026, while costs associated with the acquisition of Eastern Michigan Financial Corporation totaled $0.2 million and $0.6 million during the current-year third quarter and third quarter of 2025, respectively.  Excluding these non-recurring costs, noninterest expense increased $8.8 million during the third quarter of 2026 compared to the prior-year third quarter.  Eastern Michigan Bank’s noninterest expense totaled $4.1 million during the third quarter of 2026, including salary and benefit costs of $1.7 million and core deposit intangible asset amortization of $0.9 million.  The remaining increase in noninterest expense largely stemmed from higher salary and benefit costs, mainly reflecting increased bonus accruals, annual merit pay increases, market adjustments, and talent acquisitions to assist with the core and digital banking system conversion and expand deposit and loan market share in Southeast Michigan, along with cost inflation and a larger balance sheet.

Federal income tax expense was $4.9 million during the third quarter of 2026, compared to $3.7 million during the prior-year third quarter.  The increase in federal income tax expense mainly resulted from a higher level of income before federal income tax and a lower level of net benefits from transferable energy tax credits.  Mercantile’s effective tax rate, which equaled 16.8 percent and 13.4 percent during the third quarters of 2026 and 2025, respectively, has been positively impacted by tax benefits derived from the acquisition of transferable energy tax credits and low-income housing and historic tax credit investments.

Mr. Reitsma commented, “The notable increase in net interest income during the third quarter of 2026 resulted from robust earning asset growth and a higher net interest margin, primarily reflecting a lower cost of funds and the upward repricing of matured fixed-rate loans and securities.  We are pleased with the significant increase in treasury management fees, reflecting customers’ expanded use of products and services and our ongoing success in cultivating new client relationships.  Meeting asset growth objectives in a cost-effective manner while remaining focused on providing customers with excellent service and market-leading products and services remain important strategic objectives.  Excluding costs related to the core and digital banking system conversion and acquisition of Eastern Michigan Financial Corporation, overhead costs as a percentage of net revenue during the third quarter of 2026 increased slightly compared to the third quarter of 2025, in part reflecting investments in personnel to assist with the core and digital banking system conversion and expansion activities in Southeast Michigan.”

Balance Sheet

Total assets were $7.16 billion as of September 30, 2026, up $328 million from December 31, 2025.  Total loans increased $37.4 million, or an annualized 3.0 percent, during the third quarter of 2026, and $131 million, or an annualized 3.6 percent, during the first nine months of 2026, primarily reflecting commercial loan portfolio expansion of $20.4 million, or an annualized 2.0 percent, and $152 million, or an annualized 5.2 percent, during the respective periods.  Commercial loans grew in both 2026 periods notwithstanding the full payoffs and partial paydowns of certain larger relationships, which aggregated $147 million during the third quarter of 2026, and $448 million during the first nine months of 2026.  The payoffs and paydowns, reflecting sales of assets, secondary market refinancings, and customers using excess cash flows generated within their operations to make line of credit reductions, remained above the historical average of approximately $50 million per quarter during the third quarter of 2026.  Payoffs and paydowns during 2025 were also well above historical levels, totaling approximately $363 million and averaging about $91 million per quarter.  Commercial loan originations, consisting of loans to new customers and growth in existing credit relationships, stayed strong across all segments during the first nine months of 2026.  Residential mortgage loans increased $13.2 million during the third quarter of 2026 and declined $27.1 million during the first nine months of 2026, while other consumer loans were up $3.8 million and $6.1 million during the respective periods.

During the first nine months of 2026, interest-earning deposits grew $151 million, and securities available for sale were down $4.2 million.  The increase in interest-earning deposits primarily resulted from strong local deposit growth during the third quarter of 2026, while the reduction in securities available for sale mainly reflected an increase in the net unrealized loss on these securities stemming from the recent higher interest rate environment. 

As of September 30, 2026, unfunded commitments on commercial construction and development loans, which are expected to be funded over the next 12 to 18 months, and residential construction loans, which are expected to be largely funded over the next 12 months, totaled $266 million and $43.9 million, respectively.  The unused balance on construction loans remains relatively stable as new construction loan opportunities are identified and as construction loans shift to term real estate loans upon completion of the projects.

Commercial and industrial loans and owner-occupied commercial real estate loans combined represented approximately 55 percent of total commercial loans as of September 30, 2026, a level that has remained relatively consistent with prior periods and in line with our expectations.

Total deposits equaled $5.61 billion as of September 30, 2026, compared to $5.28 billion as of December 31, 2025.  Local deposits grew $438 million, or an annualized 11.4 percent, during the first nine months of 2026, while brokered deposits decreased $110 million.  The growth in local deposits, which occurred despite the customary level of seasonal noninterest-bearing deposit withdrawals by customers to make bonus and tax payments and partnership distributions, reflected successful customer acquisition efforts and net growth in various existing deposit relationships.  The loan-to-deposit ratio equaled 88.3 percent as of September 30, 2026, down from 92.8 percent and 91.2 percent as of June 30, 2026, and December 31, 2025, respectively, largely due to local deposit portfolio expansion.  As of September 30, 2026, wholesale funds, consisting of Federal Home Loan Bank of Indianapolis advances and brokered deposits, were $325 million, or approximately 5 percent of total funds, compared to $457 million, or approximately 8 percent of total funds, as of December 31, 2025.  Noninterest-bearing checking accounts represented approximately 26 percent of total deposits as of September 30, 2026, compared to about 25 percent as of year-end 2025.

Mr. Reitsma noted, “The commercial loan portfolio grew during the third quarter and first nine months of 2026 despite elevated levels of payoffs and line of credit paydowns, reflecting ongoing strength in loan originations.  Based on our current pipeline and continuing discussions with existing and prospective borrowers, we believe ample opportunities to book commercial loans will exist in upcoming periods.  We are pleased with the noteworthy increase in local deposits during the third quarter of 2026 and related decline in our loan-to-deposit ratio and remain focused on funding loan originations and investment purchases through local deposit generation.”

Asset Quality

Nonperforming assets totaled $9.8 million, or 0.1 percent of total assets, as of September 30, 2026, compared to $7.9 million, or 0.1 percent of total assets, as of December 31, 2025, and $9.8 million, or 0.2 percent of total assets, as of September 30, 2025.  The level of past due loans remains nominal.  During the third quarter of 2026, loan charge-offs were less than $0.1 million, while recoveries of prior period loan charge-offs equaled $0.3 million, providing for net loan recoveries of $0.3 million, or an annualized 0.02 percent of average total loans.

Mr. Reitsma remarked, “Our asset quality measures remained strong during the third quarter of 2026 as evidenced by ongoing low levels of nonperforming assets, past due loans, and loan charge-offs.  We remain steadfast in our commitment to underwrite loans across all portfolio segments cautiously and in adherence with internal policy guidelines and identify any weakening commercial loan relationships or emerging sector-specific or systemic credit issues as early as possible to minimize the impact of such on our overall financial condition.  Our commercial borrowers have generally continued to operate effectively during the extended and continuing period of uncertain macro-economic conditions, and our residential mortgage loan and consumer loan portfolios have also continued to perform well.”

Capital Position

Shareholders’ equity totaled $744 million as of September 30, 2026, up $19.0 million from December 31, 2025.  Positively impacting shareholders’ equity during the first nine months of 2026 was net income of $72.7 million and activity related to the issuance and sale of common stock through various stock-based compensation programs and our dividend reinvestment plan totaling $4.1 million, which was partially offset by a $37.8 million after-tax decrease in the market value of our available for sale securities portfolio, generally reflecting the recent increase in market interest rates, and the payment of cash dividends totaling $20.1 million.  Mercantile Bank and Eastern Michigan Bank each maintained “well-capitalized” positions as of September 30, 2026, with total risk-based capital ratios of 13.4 percent and 23.9 percent, respectively.  As of September 30, 2026, Mercantile Bank and Eastern Michigan Bank had approximately $200 million and $39 million, respectively, in excess of the 10 percent minimum regulatory threshold required to be categorized as a “well-capitalized” institution.

Mercantile reported 17,288,352 total shares outstanding as of September 30, 2026.

Mr. Reitsma concluded, “Our ongoing financial strength enabled us to continue our regular cash dividend program and once again provide shareholders with meaningful cash returns on their investments.  We believe we are well positioned to effectively address any issues emerging from the extended period of unstable economic and operating conditions as a result of sustained strength in our operating results, asset quality metrics, capital levels, and commercial loan funding opportunities, along with the anticipated attainment of solid financial performance in future periods.  Our firm commitment to meeting clients’ needs has been successful in retaining existing and fostering new relationships, and we believe the continuation of this commitment will present us with abundant opportunities to originate loans and generate local deposits in upcoming periods.  Due to the outstanding efforts of our team members, we are making steady progress regarding the core and digital banking system conversion and expect it to be completed in the first quarter of 2027 as originally planned.”

Investor Presentation

Mercantile has prepared presentation materials that management intends to use during its previously announced third quarter 2026 conference call on Tuesday, October 20, 2026, at 10:00 a.m. Eastern Time, and from time to time thereafter in presentations about the company’s operations and performance.  These materials, which are available for viewing in the Investor Relations section of Mercantile’s website at www.mercbank.com, have been furnished to the U.S. Securities and Exchange Commission concurrently with this press release.

About Mercantile Bank Corporation

Based in Grand Rapids, Michigan, Mercantile Bank Corporation is the bank holding company for Mercantile Bank and Eastern Michigan Bank.  Mercantile Bank and Eastern Michigan Bank provide financial products and services in a professional and personalized manner designed to make banking easier for businesses, individuals, and governmental units.  Distinguished by exceptional service, knowledgeable staff, and a commitment to the communities they serve, Mercantile Bank and Eastern Michigan Bank together comprise one of the largest Michigan-based banking organizations with total combined assets of approximately $7.2 billion.  Mercantile Bank Corporation's common stock is listed on the NASDAQ Global Select Market under the symbol "MBWM." For more information about Mercantile, visit www.mercbank.com, and follow us on Facebook, Instagram, X (formerly Twitter) @MercBank, and LinkedIn @merc-bank.

Reconciliation of U.S. GAAP to Non-GAAP Financial Measures

This news release contains certain non-GAAP financial measures, including adjusted net income and adjusted diluted earnings per share, each of which excludes costs associated with (i) Mercantile’s acquisition of Eastern Michigan Financial Corporation that was completed during the fourth quarter of 2025 ($0.2 million and $0.5 million during the third quarter and first nine months of 2026, respectively), and (ii) the previously announced core and digital banking system conversion ($0.4 million and $3.9 million during the third quarter and first nine months of 2026, respectively), on an after-tax basis. These non-GAAP financial measures are identified in this news release where they appear.  We believe that presenting these non-GAAP financial measures provides investors, analysts, and other interested parties with meaningful supplementary information to assess Mercantile’s underlying operational performance by removing the effect of costs we consider to be non-recurring in nature and not reflective of Mercantile’s core operating results.  These non-GAAP financial measures are used by management to evaluate Mercantile’s ongoing operations, for internal planning and forecasting purposes, and to assess period-over-period comparability.  Management believes it is useful for the reader to review these non-GAAP adjusted measures alongside the GAAP measures.  Our definition of these adjusted financial measures may differ from similarly named measures used by others.  These non-GAAP measures have limitations as an analytical tool and should not be considered in isolation or as a substitute for our GAAP measures.  Our net income and diluted earnings per share are presented on a GAAP-basis in the first paragraph of this release.

Forward-Looking Statements

This news release contains statements and information that may constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995.  Forward-looking statements can be identified by words such as: “anticipate,” “intend,” “plan,” “goal,” “seek,” “believe,” “project,” “estimate,” “expect,” “endeavor,” “strategy,” “future,” “likely,” “may,” “should,” “will,” and similar references to future periods.  Any such statements are based on current expectations that involve a number of risks and uncertainties.  Actual results may differ materially from the results expressed in forward-looking statements.  Factors that might cause such a difference include difficulties and delays in the ongoing integration of Mercantile Bank and Eastern Michigan Bank and achieving anticipated synergies, cost savings and other benefits from the transaction; delays, cost overruns, disruptions, or other difficulties in completing the core and digital banking system conversion, or failure to realize its anticipated benefits; changes in interest rates and interest rate relationships; increasing rates of inflation and slower growth rates or recession; significant declines in the value of commercial real estate; market volatility; demand for products and services; climate impacts; labor markets; the degree of competition by traditional and nontraditional financial services companies; changes in banking regulation or actions by bank regulators; changes in tax laws and other laws and regulations applicable to us; changes in prices, levies, and assessments; the impact of technological advances; potential cyber-attacks, information security breaches and other criminal activities; litigation liabilities; governmental and regulatory policy changes; the outcomes of existing or future contingencies; trends in customer behavior as well as their ability to repay loans; changes in local real estate values; damage to our reputation resulting from adverse publicity, regulatory actions, litigation, operational failures, and the failure to meet client expectations and other factors; changes in the national and local economies; unstable political and economic environments; disease outbreaks, such as the COVID-19 pandemic or similar public health threats, and measures implemented to combat them; and other factors, including those expressed as risk factors, disclosed from time to time in filings made by Mercantile with the Securities and Exchange Commission.  Mercantile undertakes no obligation to update or clarify forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.  Investors are cautioned not to place undue reliance on any forward-looking statements contained herein.

FOR FURTHER INFORMATION: