NB Bancorp, Inc.

Notes to Unaudited Consolidated Financial Statements

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

NB Bancorp, Inc., a Maryland corporation (the “Company”) (referred to herein as the “Company," “we,” “us,” or “our”), 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.

The activities of the Company are subject to the regulatory supervision of the Board of Governors of the Federal Reserve System. The activities of the Bank are subject to the regulatory supervision of the Massachusetts Commissioner of Banks and the Federal Deposit Insurance Corporation (“FDIC”). The Company and the activities of the Bank and its subsidiaries are also subject to various Massachusetts business and banking-related regulations.

On June 5, 2025, the Company announced the signing of a definitive merger agreement under which the Company will acquire Provident Bancorp, Inc., with the Company as the surviving entity, and the Bank will acquire BankProv, with the Bank as the surviving entity (the “Merger”). The transaction is valued at approximately $211.8 million. The closing of the Merger, which is expected to occur during the fourth quarter of 2025, is subject to the satisfaction of various conditions, including the affirmative vote by the holders of a majority of Provident Bancorp, Inc. common stock and the receipt of required regulatory approvals from applicable state and federal regulators.

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 June 30, 2025, the Consolidated Statements of Income, Consolidated Statements of Comprehensive Income, Consolidated Statements of Changes in Shareholders’ Equity and Consolidated Statements of Cash Flows for the three and six months ended June 30, 2025 and 2024 are unaudited. The Consolidated Balance Sheet as of December 31, 2024 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, 2024, 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 and six months ended June 30, 2025 are not necessarily indicative of results to be expected for the year ending December 31, 2025, 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 elected 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.

Operating Segments

The Company adopted FASB ASU 2023-07*“Segment Reporting (Topic 280) - Improvement to Reportable Segment Disclosures”* on January 1, 2024, which requires that information be reported about a company’s operating segments using a “management approach.” Reportable segments are identified in these standards as 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 is 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

In preparing the Consolidated Financial Statements in conformity with U.S. GAAP, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of the balance sheets and income and expenses for the periods reported. Actual results could differ from those estimates based on changing conditions, including economic conditions and future events. Material estimates that are particularly susceptible to change relate to the determination of the allowance for credit losses, valuation and fair value measurements, the liabilities for benefit obligations (particularly pensions) and the provision for income taxes.

Recent Accounting Pronouncements

Relevant standards that were recently issued but not yet adopted as of June 30, 2025:

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.

In December 2023, the FASB issued ASU 2023-09, “Income Taxes (Topic 740): Improvements to Income Tax Disclosures” to improve the transparency of income tax disclosures. The amendments are effective for annual periods beginning after December 15, 2024. Early adoption is permitted for annual financial statements that have not yet been issued or made available for issuance. The Company does not expect the adoption of ASU 2023-09 to have a material effect on its 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 securities are carried at fair value. For available-for-sale 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 available-for-sale 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, through an allowance for credit losses. 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 available-for-sale securities for the three and six months ended June 30, 2025 and 2024. Excluded from the table above is accrued interest on available-for-sale securities of $1.7 million and $1.6 million at June 30, 2025 and December 31, 2024, 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 available-for-sale securities for the three and six months ended June 30, 2025 and 2024. No securities held by the Company were delinquent on contractual payments at June 30, 2025 or December 31, 2024, nor were any securities placed on non-accrual status for the three and six months ended June 30, 2025 and 2024.

The following is a summary of actual maturities of certain available-for-sale securities as of June 30, 2025. 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 available-for-sale securities during the three and six months ended June 30, 2025 and 2024.

There wereno available-for-sale securities pledged to secure borrowings as of June 30, 2025 and December 31, 2024.

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 June 30, 2025, available-for-sale debt securities had unrealized losses with aggregate depreciation of 4.8% 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 available-for-sale debt securities until maturity or cost recovery, no allowance for credit losses on securities is deemed necessary as of June 30, 2025 and December 31, 2024.

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

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”). For originated loans, loan fees and certain direct origination costs are deferred and amortized or accreted into interest income over the contractual life of the loan using the level-yield method. When a loan is paid off, the unamortized portion is recognized in interest income.

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 and the borrower demonstrated the ability to pay and remain 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 Allowance for Credit Losses (“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. This determination is made based on management's review of specific facts and circumstances of the individual loan, including the expected cash flows to repay the loan, the value of the collateral and the ability and willingness of any guarantors to perform. Subsequent recoveries of previously charged-off amounts are recorded as increases to the ACL. The provision for credit losses on loans 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 underFinancial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 326 – Financial Instruments – Credit Losses 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 Current Expected Credit Loss (“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 weighted average life.

In applying future economic forecasts, the Company utilizes a forecast period of up to two years. Historical loss rates used in the quantitative model are primarily derived using both the Bank’s data, supplemented with peer bank data obtained from publicly available sources. Management also considers qualitative adjustments when estimating credit losses in consideration of the model’s quantitative limitations.

Qualitative adjustments to quantitative loss factors, either negative or positive, may include considerations of economic conditions, 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 and six months ended June 30, 2025 and 2024.

For those loans that do not share similar risk characteristics, the Company estimates the ACL 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 and a balance exceeding $500,000, 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 individually evaluated loans.

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.

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 $441.9 million and $459.6 million in loans to borrowers in the cannabis industry at June 30, 2025 and December 31, 2024, respectively. Of that total, $268.3 million and $321.9 million were direct loans to cannabis companies and were collateralized by real estate at June 30, 2025 and December 31, 2024, respectively.

During the three months ended June 30, 2025, the Company didnot purchase any consumer loan pools. During the three months ended June 30, 2024, the Company purchased approximately $14.1 million of consumer loan pools. During the six months ended June 30, 2025 and 2024, the Company purchased approximately $14.4 million and $19.6 million of consumer loan pools, respectively. The loans purchased during the six months ended June 30, 2025 included loan pools collateralized by automobiles. The loans purchased during the three and six months ended June 30, 2024 included loan pools collateralized by boats, recreational vehicles, automobiles and solar panels.

The outstanding balances of these purchased consumer loan pools, 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 $1.24 billion as of June 30, 2025 and December 31, 2024, respectively.

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

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

During the three and six months ended June 30, 2025, the Company reversed$457,000 and$494,000 of interest income for loans that were placed on non-accrual respectively. During the three and six months ended June 30, 2024, the Company reversed$149,000 of interest income for loans that were placed on non-accrual.

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.

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 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 June 30, 2025. Also presented are current period gross charge-offs by loan type and vintage year for the three months ended June 30, 2025:

(1) Consumer loans are not formally risk rated and included $1.5 million of loans on non-accrual as of June 30, 2025.

The following table presents the amortized cost of loans receivable by internal risk grade by year of origination as of December 31, 2024. Also presented are current period gross charge-offs by loan type and vintage year for the three months ended December 31, 2024:

(1) Consumer loans are not formally risk rated and included $2.4 million of loans on non-accrual as of December 31, 2024.

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