NB Bancorp, Inc.

Notes to Unaudited Consolidated Financial Statements

Note 1 – Corporate Structure and Nature of Operations; Basis of Presentation

Corporate Structure and Nature of Operations

NB Bancorp, Inc., a Maryland corporation (the “Company”), is a bank holding company. Through its wholly-owned subsidiary, Needham Bank (the “Bank”), the Company provides a variety of banking services, through its full-service bank branches, located primarily in eastern Massachusetts and southern New Hampshire.

The activities of the Company and the Bank are subject to the regulatory supervision of the Board of Governors of the Federal Reserve System and the Massachusetts Commissioner of Banks. The Company and the activities of the Bank and its subsidiaries are also subject to various Massachusetts business and banking regulations.

Conversion

Effective December 27, 2023, NB Financial, MHC (the “MHC”), the Bank’s former mutual holding company and the predecessor of the Company, converted from a mutual holding company into a publicly traded stock form of organization. In connection with the conversion, the Company sold 40,997,500 shares of common stock in a public offering at $10.00 per share for net offering proceeds of approximately $400.4 million. Additionally, the Company donated $2.0 million of cash and 1,708,229 shares of common stock to the Needham Bank Charitable Foundation (the “Foundation”).

In connection with the conversion, liquidation accounts are established by the Company and the Bank in an aggregate amount equal to (i) the MHC’s ownership interest in the shareholders’ equity of NB Financial, Inc. as of the date of the latest statement of financial condition included in the Company’s definitive prospectus dated October 12, 2023, plus (ii) the value of the net assets of the MHC as of the date of the MHC’s latest statement of financial condition before the consummation of the Conversion (excluding the MHC’s ownership interest in NB Financial, Inc.). Each eligible account holder and supplemental eligible account holder is entitled to a proportionate share of the liquidation accounts in the event of a liquidation of (i) the Company and the Bank or (ii) the Bank, and only in such events. This share will be reduced if the eligible account holder’s or supplemental account holder’s deposit balance falls below the amounts on the date of record and will cease to exist if the account is closed. The liquidation account will never be increased despite any increase after conversion in the related deposit balance. The Bank may not pay a dividend on its capital stock if the effect thereof would cause retained earnings to be reduced below the liquidation account amount or regulatory capital requirements.

Basis of Presentation

The Company’s Consolidated Financial Statements have been prepared in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”) as set forth by the Financial Accounting Standards Board (“FASB”) and its Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) as well as the rules and interpretive releases of the U.S. Securities and Exchange Commission (“SEC”) under the authority of federal securities laws.

The Consolidated Financial Statements of the Company include the balances and results of operations of the Company and the Bank, its wholly-owned subsidiary, as well as the Bank’s wholly-owned subsidiaries, Needco-op Investment Corporation, Inc., 1892 Investments LLC and Eaton Square Realty LLC. All intercompany accounts and transactions have been eliminated in consolidation.

Certain amounts, previously reported, have been reclassified to state all periods on a comparable basis and had no effect on shareholders’ equity or net income.

The accompanying Consolidated Balance Sheet as of March 31, 2026, the Consolidated Statements of Income, of Comprehensive Income, of Changes in Shareholders’ Equity and of Cash Flows for the three months ended March 31, 2026 and 2025 are unaudited. The Consolidated Balance Sheet as of December 31, 2025 was derived from the Audited Consolidated Financial Statements as of that date. The interim Consolidated Financial Statements and the accompanying notes should be read in conjunction with the annual Consolidated Financial Statements and the accompanying notes contained within the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2025, as filed with the SEC. In the opinion of management, the Company’s Consolidated Financial Statements reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the results of operations for the periods presented. The results for the three months ended March 31, 2026 are not necessarily indicative of results to be expected for the year ending December 31, 2026, any other interim period, or any future year or period.

The Company qualifies as an emerging growth company (“EGC”) under the Jumpstart Our Business Startups Act of 2012 and has the ability to defer the adoption of new or revised accounting standards until the nonpublic company effective dates. As such, the Company will adopt standards on the nonpublic company effective dates until such time that we no longer qualify as an EGC.

Subsequent events are events or transactions that occur after the balance sheet date but before consolidated financial statements are issued. Recognized subsequent events are events or transactions that provide additional evidence about conditions that existed at the date of the consolidated balance sheet, including the estimates inherent in the process of preparing consolidated financial statements. Non-recognized subsequent events are events that provide evidence about conditions that did not exist at the date of the consolidated balance sheet but arose after that date.

Provident Bancorp, Inc. and BankProv Acquisition

On November 15, 2025, the Company completed its acquisition of Provident Bancorp, Inc. and BankProv (“Provident”). The total consideration paid in the acquisition of Provident was $111.8 million in cash and the issuance of 5,943,682 shares of common stock valued at $114.7 million. The acquisition added $1.40 billion of total assets, $1.23 billion of total loans and $1.14 billion in total deposits, each at fair value, as of the date of closing.

The acquisition was accounted for under the acquisition method of accounting in accordance with ASC Topic 805,Business Combinations. Under this method of accounting, the respective assets acquired and liabilities assumed were recorded at their estimated fair values. The excess of consideration paid over the estimated fair value of the net assets acquired totaled $18.5 million and was recorded as goodwill. The results of Provident’s operations were included in the Company’s consolidated financial statements beginning on November 15, 2025.

The calculation of goodwill is subject to change for up to one year after the closing date of the transaction as additional information relative to closing date estimated and uncertainties becomes available. The Company madeno adjustments to Goodwill during the three months ended March 31, 2026.

Operating Segments

Reportable segments are those revenue producing components for which separate financial information is produced internally and which are subject to evaluation by the chief operating decision maker (“CODM”). The Company has determined that its CODM is its Chief Executive Officer. The Company hasone reportable segment: its banking business, which consists of a full range of banking lending, savings, and small business offerings. The CODM regularly assesses performance of the aggregated single operating and reporting segment and decides how to allocate resources based on net income calculated on the same basis as net income reported in the Company’s consolidated statements of income and other comprehensive income. The CODM is also regularly provided with expense information at a level consistent with that disclosed in the Company’s consolidated statements of income and other comprehensive income.

Note 2 – Summary of Significant Accounting Policies

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the reported amounts of revenues and expenses. Actual results could differ from those estimates.

Material estimates that are particularly susceptible to significant change in the near term relate to the determination of the Allowance for Credit Losses (“ACL”) on loans, fair value determination of acquired assets and liabilities and resulting accretion and amortization of purchase accounting premiums/discounts, the valuation of real estate acquired in connection with foreclosures or in satisfaction of loans, the valuation of deferred tax assets, actuarial estimates related to the Company’s retirement programs, the valuation of financial instruments and impairment of goodwill and other intangibles. In connection with the determination of the ACL and foreclosed real estate, management obtains independent appraisals for significant properties.

A majority of the Company's loan portfolio consists of one-to-four-family residential, commercial real estate and construction and land development loans in the metro-west area of Boston and its surrounding communities. Accordingly, the ultimate collectability of a substantial portion of the Company's loan portfolio and the recovery of the carrying amount of foreclosed real estate are susceptible to changes in local market conditions.** **

While management uses currently available information to recognize losses on loans and foreclosed real estate, future additions to the ACL and valuation reserves on foreclosed real estate may be necessary based on changes in local economic conditions. In addition, regulatory agencies, as an integral part of their examination process, periodically review the Company’s ACL on loans and valuation reserves on foreclosed real estate. Such agencies may require the Company to recognize additions to the ACL on loans and valuation reserves on foreclosed real estate based on their judgments about information available to them at the time of their examination. Because of these factors, it is reasonably possible that the ACL on loans and valuation reserves on foreclosed real estate may change in the near future.

Business Combinations – Acquisitions of businesses are accounted for using the acquisition method of accounting. In accordance with applicable accounting guidance, we recognize assets acquired and liabilities assumed at their respective fair values as of the date of acquisition, with the related transaction costs expensed in the period incurred. We use third party valuation specialists to assist in the determination of fair value of certain assets and liabilities at the merger date, including loans and core deposit intangibles. While we use our best estimates and assumptions to accurately value assets acquired and liabilities assumed on the acquisition date, the estimates are inherently uncertain.

For further discussion of our methodology for estimating the fair value of acquired assets and assumed liabilities in connection with our Provident Acquisition, seeNote 1 – Corporate Structure and Nature of Operations; Basis of Presentation – Provident Bancorp, Inc. and BankProv Acquisition.

Recent Accounting Pronouncements

Relevant standards that were recently issued but not yet adopted as of March 31, 2026:

In November 2024, the FASB issued ASU 2024-03, “Income Statement – Reporting Comprehensive Income – Expense Disaggregation Disclosures (Sub Topic 220-40): Disaggregation of Income Statement Expenses”. ASU 2024-03 improves disclosures about a public business entity’s expenses and addresses requests from investors for more detailed information about the types of expenses (including purchases of inventory, employee compensation, depreciation, amortization, and depletion) in commonly presented expense captions (such as cost of sales, SG&A, and research and development). ASU 2024-03 is effective for annual reporting periods beginning after December 15, 2026 and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The adoption of ASU 2024-03 is not expected to have a material impact on the Company’s consolidated financial statements.

Other accounting standards that have been issued or proposed by the FASB or other standards-setting bodies are not expected to have a material impact on the Company’s financial position, results of operations or cash flows.

Note 3 – Securities

The Company's available-for-sale (“AFS”) securities are carried at fair value. For AFS securities in an unrealized loss position, management will first evaluate whether there is intent to sell, or if it is more likely than not that the Company will be required to sell a security prior to anticipated recovery of its amortized cost basis. If either of these criteria are met, the Company will record a write-down of the security's amortized cost basis to fair value through income. For those AFS securities which do not meet the intent or requirement to sell criteria, management will evaluate whether the decline in fair value is a result of credit related matters or other factors.

In performing this assessment, management considers the creditworthiness of the issuer including whether the security is guaranteed by the U.S. Federal Government or other government agency, the extent to which fair value is less than amortized cost, and changes in credit rating during the period, among other factors. If this assessment indicates the existence of credit losses, the security will be written down to fair value, as determined by a discounted cash flow analysis. To the extent the estimated cash flows do not support the amortized cost, the deficiency is considered to be due to credit loss and is recognized in earnings.

Changes in the allowance for credit losses are recorded as a provision for (or reversal of) credit loss expense. Losses are charged against the allowance when the uncollectibility of a security is confirmed, or when either of the aforementioned criteria surrounding intent or requirement to sell have been met.

Securities have been classified on the consolidated balance sheets according to management’s intent.

The following tables summarize the amortized cost, allowance for credit losses, and fair value of securities and their corresponding amounts of unrealized gains and losses at the dates indicated:

The Company did not record a provision for estimated credit losses on any AFS securities for the three months ended March 31, 2026 and 2025. Excluded from the table above is accrued interest on AFS securities of $2.1 million and $1.8 million at March 31, 2026 and December 31, 2025, respectively, which is included within accrued interest receivable on the consolidated balance sheets. Additionally, the Company didnot record any write-offs of accrued interest income on AFS securities for the three months ended March 31, 2026 and 2025. No securities held by the Company were delinquent on contractual payments at March 31, 2026 or December 31, 2025, nor were any securities placed on non-accrual status during the three months ended March 31, 2026 and 2025.

The following is a summary of actual maturities of certain AFS securities as of March 31, 2026. The amortized cost and fair values are based on the contractual maturity dates. Actual maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without penalty.

Agency mortgage-backed securities and collateralized mortgage obligations are presented as separate lines as paydowns are expected to occur before contractual maturity dates.

When securities are sold, the adjusted cost of the specific security sold is used to compute the gain or loss on the sale. There wereno sales of AFS securities during the three months ended March 31, 2026 and 2025.

The carrying value of AFS securities pledged to secure advances from the FHLB were $216.4 million and $111.5 million as of March 31, 2026 and December 31, 2025, respectively.

The following tables present fair value and gross unrealized losses, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, as of the dates stated.

Management evaluates securities for expected credit losses at least on a quarterly basis, and more frequently when economic or market concerns warrant such evaluation.

Included in corporate bonds are investments in senior and subordinated debt of banks and bank holding companies, some of which do not have investment ratings.

At March 31, 2026, AFS debt securities had unrealized losses with aggregate depreciation of 2.7% from the Company’s amortized cost basis. These unrealized losses relate to changes in market interest rates since acquiring the securities. As management has the intent and ability to hold these securities until maturity or cost recovery, no allowance for credit losses on securities is deemed necessary as of March 31, 2026 and December 31, 2025.

Note 4 – Loans Receivable, Allowance for Credit Losses and Credit Quality

Loans Held for Sale

Loans held for sale to the secondary market are carried at the lower of cost or estimated market value on an individual loan basis. Gains on sales of loans are recognized in the consolidated statements of income at the time of sale. Losses on sales of loans are recognized in the consolidated statements of income when incurred. Interest income is recognized on loans held for sale between the time the loan is funded and the loan is sold. Direct loan origination costs and fees are deferred upon origination and are recognized in the consolidated statements of income on the date of sale. As of March 31, 2026 and December 31, 2025, the Company had$64.0 million and$66.4 million of consumer loans held for sale, respectively.

Loans Receivable

Loans that management has the intent and ability to hold for the foreseeable future or until maturity or pay-off are reported as held for investment at their outstanding principal balance adjusted for any charge-offs and net of any deferred fees (including purchase accounting adjustments) and origination costs (collectively referred to as “amortized cost”). Loan origination fees and certain direct origination costs are deferred and amortized as an adjustment of yield using the payment terms required by the loan contract. When loans are sold or repaid, any unamortized fees and costs are recorded to interest income on loans. Interest income on loans is accrued based upon the daily principal amount outstanding except for loans on non-accrual status. For acquired loans with no signs of credit deterioration at acquisition, interest income is also accrued based upon the daily principal amount outstanding, adjusted further by the accretion of any discount or amortization of any premium associated with the loan.

Loans are generally placed into nonaccrual status when they are past due 90 days or more as to either principal or interest or when, in the opinion of management, the collection of principal and/or interest is in doubt. A loan remains in nonaccrual status until the loan is current as to payment of both principal and interest or past due less than 90 days and the borrower demonstrates the ability to pay and remain current. When cash payments are received, they are applied to principal first, then to accrued interest. It is the Company’s policy not to record interest income on nonaccrual loans until principal has become current. In certain instances, accruing loans that are past due 90 days or more as to principal or interest may not go on nonaccrual status if the Company determines that the loans are well-secured and are in the process of collection.

Allowance for Credit Losses

The ACL represents management’s best estimate of credit losses over the remaining life of the loan portfolio. Loans are charged-off against the ACL when management believes the loan balance is no longer collectible. Subsequent recoveries of previously charged-off amounts are recorded as increases to the ACL. The provision for credit losses is an amount sufficient to bring the ACL to an estimated balance that management considers adequate to absorb lifetime expected losses in the Company’s held-for-investment loan portfolio. The ACL is a valuation account that is deducted from the loans’ amortized cost basis to present the net amount expected to be collected on the loans.

Management’s determination of the adequacy of the ACL under FASB ASC 326 is based on an evaluation of the composition of the loan portfolio, current economic conditions, historical loan loss experience, reasonable and supportable forecasts, and other risk factors. The Company uses a third-party CECL model as part of its estimation of the ACL on a quarterly basis. Loans with similar risk characteristics are collectively assessed within pools (or segments). Loss estimates within the collectively assessed population are based on a combination of pooled assumptions and loan-level characteristics. The Company has determined that using federal call codes is an appropriate loan segmentation methodology, as it is generally based on risk characteristics of a loan’s underlying collateral.

Using federal call codes also allows the Company to utilize and assess publicly available external information when developing its estimate of the ACL. The weighted average remaining maturity (“WARM”) method is the primary credit loss estimation methodology used by the Company and involves estimating future cash flows and expected credit losses for pools of loans using their expected remaining WARM.

In applying future economic forecasts, the Company utilizes a forecast period of up to two years. The Company considers economic forecasts of inflation, national gross domestic product, and unemployment rates sourced from the Federal Open Market Committee’s “Summary of Economic Projections” to inform the model for future loss estimation.

Additionally, interest rate forecasts sourced from CME Group’s “FedWatch”, Wells Fargo’s “U.S. Economic Outlook,” and FHN Financial’s “Economic Forecast” publications are used for consideration of rate sensitivity in the model’s loan prepayment speed estimation. Historical loss rates used in the quantitative model are primarily derived using both the Bank’s data and peer bank data obtained from publicly available sources (i.e., federal call reports). The Bank’s peer group is comprised of financial institutions of relatively similar size and in similar markets (i.e., $10 billion or less of total assets and headquartered in New England). The peer group used for certain loan segments is a national peer group of financial institutions of relatively similar size, where appropriate. The changes did not have a material impact on the ACL during the year ended December 31, 2025.

Management also considers qualitative adjustments when estimating credit losses to take into account the model’s quantitative limitations.

Management continually assesses the peer group and related data used to inform the ACL calculation.

Qualitative adjustments to quantitative loss factors, either negative or positive, may include considerations of economic conditions including economic forecasts as detailed above, volume and severity of past due loans, value of underlying collateral, experience, depth, and ability of management, and concentrations of credit.

The Company made no significant changes to loss factors, assumptions nor qualitative factors within the CECL model during the three months ended March 31, 2026 and 2025.

For those loans that do not share similar risk characteristics, the Company evaluates the ACL needs on an individual (or loan by loan) basis. This population of individually evaluated loans (or loan relationships with the same primary source of repayment) is determined on a quarterly basis and consists of: loans with a risk rating of substandard or worse or loan terms differing significantly from other pooled loans. In accordance with the Company’s policy, non-accrual residential real estate loans that are below $500,000 and well secured (loan-to-value <60%) are excluded from being individually evaluated.

Measurement of credit loss is based on the expected future cash flows of an individually evaluated loan, discounted at the loan’s effective interest rate, or measured on an observable market value, if one exists, or the estimated market value of the collateral underlying the loan, discounted to consider estimated costs to sell the collateral for collateral-dependent loans. If the net value is less than the loan’s amortized cost, a specific reserve in the ACL is recorded, which is charged-off in the period when management believes the loan balance is no longer collectible.

The Company’s Troubled Asset Resolution Committee approves the key methodologies and assumptions, as well as the ACL on at least a quarterly basis. While management uses available information at the time of estimation to determine expected credit losses on loans, future changes in the ACL may be necessary based on changes in portfolio composition, portfolio credit quality, and/or economic conditions. In addition, bank regulatory agencies periodically review the Bank’s ACL and may require an increase in the provision for credit losses or the recognition of further loan charge-offs, based on judgments different than those of management.

**Collateral-dependent Loans –**The Company has certain loans for which repayment is dependent upon the operation or sale of collateral, as the borrower is experiencing financial difficulty. The underlying collateral can vary based upon the type of loan. The following provides more detail about the types of collateral that secure collateral-dependent loans:

Non-owner-occupied commercial real estate loans are generally secured by office buildings and complexes, retail facilities, multifamily complexes, land under development, industrial properties, as well as other commercial or industrial real estate.

**Purchased Credit-Deteriorated (“PCD”) Loans -**PCD loans are acquired individual loans (or acquired groups of loans with similar risk characteristics) that, as of the date of acquisition, have experienced a more-than-insignificant deterioration in credit quality, as determined by the Company’s analyses. A PCD loan is recorded at its purchase price plus the ACL expected at the time of acquisition, or “gross up” of the amortized cost basis, if any. Changes in the current estimate of the ACL subsequent to acquisition from the estimated allowance previously recorded are recognized in the income statement as provision for credit losses or recoveries of credit losses in subsequent periods as they arise.

Evidence that purchased loans, measured at amortized cost, have more-than-insignificant deterioration in credit quality and, therefore meet the PCD definition, may include past-due status, non-accrual status, risk rating and other standard indicators (i.e., modification due to financial difficulty, charge-offs, bankruptcy).

In the ordinary course of business, the Company enters into commitments to extend credit. Such financial instruments are recorded in the consolidated financial statements when they are funded. The credit risk associated with these commitments is evaluated in a manner similar to the ACL on loans. The reserve for unfunded commitments is included in other liabilities on the consolidated balance sheets.

Loans consist of the following as of the dates stated:

Included in the above are approximately $466.8 million and $404.8 million in loans to borrowers in the cannabis industry at March 31, 2026 and December 31, 2025, respectively. Of that total, $321.0 million and $228.8 million were direct loans to cannabis companies and were collateralized by real estate at March 31, 2026 and December 31, 2025, respectively.

During the three months ended March 31, 2026 and 2025, the Company purchased approximately $14.7 million and $14.4 million of consumer loan pools, respectively. The loans purchased during the three months ended March 31, 2026 and 2025 included loan pools collateralized by automobiles.

The outstanding balances of consumer purchased loans, shown net of premium (discount) are as follows as of the dates stated:

The carrying value of loans pledged to secure advances from the FHLB were $1.25 billion and $1.56 billion as of March 31, 2026 and December 31, 2025, respectively.

The following table presents the aging of the amortized cost of loans receivable by loan category as of the date stated:

As of March 31, 2026, the Company hadone commercial and industrial loan with an outstanding balance of $12.7 million that was ninety days past due and still accruing. The loan is well secured and in the process of collection, as the borrower has brought the loan current. The Company hadno loans ninety days past due and still accruing as of March 31, 2025.

The following table presents the amortized cost of nonaccrual loans receivable by loan category as of the dates stated:

During the three months ended March 31, 2026 and 2025, the Company reversed$483,000 and$378,000 of interest income for loans that were placed on non-accrual respectively.

Credit Quality Information

The Company utilizes a nine-grade internal rating system for all loans, except consumer loans, which are not risk rated, as follows:

Loans rated 1-5: Loans in these categories are considered “pass” rated loans with low to average risk.

Loans rated 6: Loans in this category are considered “special mention”. These loans are starting to show signs of potential weakness and are being closely monitored by management.

Loans rated 7: Loans in this category are considered “substandard”. Generally, a loan is considered substandard if it is inadequately protected by the current net worth and paying capacity of the obligors and/or the collateral pledged. There is a distinct possibility that the Company will sustain some loss if the weakness is not corrected. Non-accrual residential real estate and commercial loans are downgraded to a substandard risk rating.

Loans rated 8: Loans in this category are considered “doubtful”. Loans classified as doubtful have all the weaknesses inherent in those classified as substandard with the added characteristic that the weaknesses make collection or liquidation in full, on the basis of currently existing facts, highly questionable and improbable.

Loans rated 9: Loans in this category are considered uncollectible (“loss”) and of such little value that their continuance as loans is not warranted.

On an annual basis, or more often if needed, the Company reviews the accuracy of risk ratings for all commercial real estate, construction and land development loans, and commercial and industrial loans based on various ongoing performance characteristics and supporting information that is provided from time to time by commercial borrowers. Annually, the Company engages an independent third-party to review a significant portion of loans within these segments. Management uses the results of these reviews as part of its annual review process.

The following table presents the amortized cost of loans receivable by internal risk grade by year of origination as of March 31, 2026. Also presented are current period gross charge-offs by loan type and vintage year for the three months ended March 31, 2026:

(1) Consumer loans are not formally risk rated and included $2.8 million of loans on non-accrual as of March 31, 2026.

The following table presents the amortized cost of loans receivable by internal risk grade by year of origination as of December 31, 2025. Also presented are current period gross charge-offs by loan type and vintage year for the three months ended December 31, 2025:

(1) Consumer loans are not formally risk rated and included $2.2 million of loans on non-accrual as of December 31, 2025.

The following table presents an analysis of the change in the ACL by major loan segment for the periods stated: