Note 1 – Description of Plan –

The following brief description of b1BANK Employee Retirement Plan and Trust (the “Plan” or “Plan Sponsor”) provides only general information. Participants should refer to the plan agreement for more complete information.

Description of Plan

The Plan is a defined contribution plan which covers all eligible employees of b1BANK (the “Bank” or “Plan Sponsor”) who are at least 21 years of age and meet the service requirements as defined in the Plan. The Plan includes an automatic enrollment and deferral provision in which, upon meeting the eligibility requirements, an employee is automatically enrolled in the Plan to defer 4% of compensation. The Plan is subject to the provisions of the Employee Retirement Income Security Act of 1974 (“ERISA”).

On October 1, 2024, Business First Bancshares, Inc., parent bank holding company of b1BANK, the plan sponsor completed the acquisition of Oakwood Bancshares, Inc. (“Oakwood”), the holding company for Oakwood Bank, located in the Dallas, Texas region. Effective May 6, 2025, $4,274,381 of plan assets including $130,596 of participant loans from Oakwood’s retirement plan, Oakwood Bank 401(k) Plan, were transferred to and merged into the Plan.

Management and the Employee Retirement and Trust Committee of b1BANK oversee governance of the Plan, determine the appropriateness of the Plan’s investment offerings, and monitor investment performance.

Contributions

Participants may contribute an amount equal to a percentage of their compensation earned during the plan year not to exceed the limits imposed by Section 401(k) of the Internal Revenue Code. Participants who have attained age 50 before the end of the Plan year are eligible to make catch-up contributions. Participants may also contribute amounts representing distributions from other qualified defined benefit or contribution plans.

The Bank will make a safe harbor matching contribution to participants of the Plan equal to 100% of the participant’s elective deferral that does not exceed 4% of the participant’s compensation. The Bank may also make discretionary matching and profit-sharing contributions to all eligible participants of the Plan. For the year ended December 31, 2025, the Bank made safe harbor matching contributions which totaled $3,100,503. No discretionary matching or profit-sharing contributions were made for the year ended December 31, 2025.

Participant Accounts

Each participant’s account is charged or credited with the participant’s contribution and the allocation of the Bank’s contribution, the Plan’s investment earnings or losses and charged with certain Plan administrative expenses. Allocations are based upon participant earnings or account balances, as defined by the Plan document. The benefit to which a participant is entitled is the benefit that can be provided from the participant’s vested account.

Vesting

Participants are immediately vested in their voluntary contributions plus actual earnings thereon and in the Bank’s safe harbor matching contributions. Additionally, for plans merged as the result of an acquisition by the Bank, participants of the acquired company who transfer contributions into the Plan retain the vesting schedule of their prior plan.

Notes Receivable from Participants

Participants may borrow from their fund accounts a minimum of $1,000 up to a maximum of $50,000, or 50%, of their vested account balance, whichever is less. The loans are secured by the balance in the participant’s account. The loan interest rate is determined at two percent above the prime rate, as defined by the loan policy. Principal and interest are paid ratably through payroll deductions.

Payment of Benefits

Upon retirement or termination of service, participants are entitled to receive a lump sum payment equal to the value of their vested account balance. Benefits are recorded when paid.

Forfeited Accounts

At December 31, 2025 and 2024, forfeited non-vested accounts totaled $9,229 and $3,213, respectively, and are included in Investments, at Contract Value in the Statements of Net Assets Available for Benefits. These accounts may be used to reduce employer contributions or to pay plan expenses. During the year ended December 31, 2025, the forfeited non-vested accounts of $9,414 were used to pay plan expenses.

Revenue Sharing

At December 31, 2025 and 2024 there were $31,827 and $21,060 of revenue sharing account balances available, respectively. For the year ended December 31, 2025, $10,398 was earned to pay future plan expenses. Revenue sharing accounts are used to pay plan expenses or are reallocated to participant's accounts.

Note 2 – Summary of Accounting Policies –

Note 3 – Plan Termination –

Although they have not expressed any intent to do so, the Bank has the right to discontinue its contributions at any time and to terminate the Plan subject to the provisions of ERISA. In the event of Plan termination, participants become fully vested in their accounts.

Note 4 – Tax Status –

The Plan has adopted a non-standardized pre-approved profit sharing plan with CODA which received a favorable determination from the Internal Revenue Service on June 30, 2020. The Plan itself has not separately applied for recognition of tax-exempt status. However, the Plan administrator believes the Plan is currently designed and being operated in compliance with applicable requirements of the Internal Revenue Code. Therefore, no provision for income taxes has been included in the Plan’s financial statements.

GAAP requires plan management to evaluate tax positions taken by the Plan and recognize a tax liability (or asset) if the Plan has taken an uncertain position that more likely than not would not be sustained upon examination by the Internal Revenue Service. The Plan is subject to routine audits by taxing jurisdictions; however, there are currently no audits for any tax periods in progress. With few exceptions, the Plan is no longer subject to income tax examinations for years prior to 2021.

Note 5 – Fair Value Measurements –

The fair value measurement accounting literature provides a framework for measuring fair value. That framework provides a fair value hierarchy that provides the inputs to valuation techniques used to measure fair value. This hierarchy consists of three broad levels. Level 1 inputs to the valuation methodology are based on unadjusted quoted prices for identical assets in active markets that the Plan has the ability to access. Level 2 inputs are based primarily on quoted prices for similar assets in active or inactive markets and/or based on inputs that are derived principally from or corroborated by observable market data by correlation or other means. Level 3 inputs are unobservable and are based on assumptions market participants would utilize in pricing the asset.

The Plan uses appropriate valuation techniques based on the available inputs to measure the fair value of its investments. The asset’s fair value measurement level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Valuation techniques maximize the use of observable inputs and minimize the use of unobservable inputs.

Following is a description of the valuation methodologies used for assets measured at fair value. There have been no changes in the valuation methodologies used at December 31, 2025 and 2024.

Registered Investment Company Accounts: The registered investment company accounts (“RIAs”) are valued at the net asset value (“NAV”) of shares held by the Plan at year-end, based upon quoted market prices.

Common and Collective Trusts: The Common and Collective Trust accounts (“CCTs”) are valued at the NAV held by the Plan at year-end, based upon quoted market prices, when available. Due to the unique investments that may be allowed in these funds, use of the NAV is a practical expedient for measuring these funds at fair value and the accounts are excluded from the Fair Value disclosure table below.

Employer Stock: The employer stock is an account comprised of common stock of Business First Bancshares, Inc and short term investments. The fair value of the fund is derived from the fair value of the common stock based on quoted market prices in an active market.

Although the Plan believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date.

b1BANK EMPLOYEE RETIREMENT PLAN AND TRUST

The following table sets forth the level, within the fair value hierarchy, the Plan’s assets at fair value as of December 31, 2025 and 2024:

*Certain investments that were measured at net asset value per share (“NAV”) practical expedient of the fund have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Statements of Net Assets Available for Benefits.

b1BANK EMPLOYEE RETIREMENT PLAN AND TRUST

The following tables summarize investments measured at fair value based on NAV per share practical expedient as of December 31, 2025 and 2024.

NOTE 6 - Fully Benefit-Responsive Investment Contract -

In October 2020, the Plan entered into a benefit-responsive investment contract with Great-West Life & Annuity Insurance Company (GWI), specifically the Group Unallocated Fixed Deferred Annuity contract (the “Contract”). The Contract, a traditional guaranteed investment contract, maintains the contributions in a general account. The account is credited with earnings on the underlying investments and charged for participant withdrawals and administrative expenses. The contract is included in the financial statements at contract value as reported to the Plan by GWI. Contract value represents contributions made under the contract, plus earnings, less participant withdrawals and administrative expenses. Participants may ordinarily direct the withdrawal or transfer of all or a portion of their investment at contract value.

The guaranteed interest contract issuer is contractually obligated to repay the principal and interest earned at a specified interest rate that is guaranteed to the Plan.

The guaranteed investment contract is fully benefit-responsive, and as such contract value is the relevant measurement attribute for that portion of the net assets available for benefits attributable to the guaranteed interest contract. There are no reserves against contract value for credit risk of the contract issuer or otherwise.

b1BANK EMPLOYEE RETIREMENT PLAN AND TRUST

The fair value of the investment contract was $2,977,251 and $2,295,942 at December 31, 2025 and 2024, respectively. The average crediting interest rate is calculated by dividing the annual interest credited to the participants during the plan year by the average annual fair value of the investment. The separate account guaranteed interest contract does not allow the crediting interest rate below zero percent.

Certain events limit the ability of the Plan to transact at contract value with the issuer. Such events include the following: (1) complete or partial termination of the Plan, (2) the establishment or activation of, or material change in, any Plan investment fund, or an amendment to the Plan or a change in the administration or operation of the Plan, including offering a competing fund (a fund with similar investment strategies and assets as the Contract) without the approval of GWI. The guaranteed interest contract permits contract termination with sufficient notice or with other violations of the contractual terms. The Plan administrator does not believe that any events have occurred which would limit the Plan’s ability to transact at contract.

Note 7 – Party-In-Interest Transactions –

A portion of the Plan’s assets are invested in Business First Bancshares, Inc. stock, the parent company of the Plan Sponsor, for which Reliance Trust serves as the independent fiduciary for the common stock fund. The Plan also holds notes receivable representing participant loans. Empower Advised Group, LLC & Empower Annuity Insurance Company of America (“Empower”) serves as investment manager for the Plan and Empower is also the Plan’s recordkeeper, respectively. Gallagher Benefits Services serves as investment advisor for the Plan. Sentinel Pension and Payroll provides administration and accounting services to the Plan. The Plan Sponsor also pays directly, certain administrative expenses of the Plan. All of these transactions qualify as party-in-interest transactions. The Plan Sponsor believes that all of these party-in-interest transactions are exempt from the prohibited transaction rules of ERISA.

Note 8 – Subsequent Events –

On January 1, 2026, Business First Bancshares, Inc., parent bank holding company of b1BANK, the plan sponsor completed the acquisition of Progressive Bancorp, Inc. (“Progressive”), the holding company for Progressive Bank, located in the northeast Louisiana region. Effective June 23, 2026, $3,850,607 of plan assets from Progressive’s retirement plan, Progressive Bank 401(k) Plan, were transferred to the Plan.

b1BANK EMPLOYEE RETIREMENT PLAN AND TRUST

EIN: 20-3977125 PN: 001

FORM 5500 SCHEDULE H LINE 4(i) – SCHEDULE OF ASSETS HELD (HELD AT END OF YEAR)

AS OF DECEMBER 31, 2025

See report of independent registered public accounting firm.