Corporate Structure and Nature of Operations: Basis of Presentation	3 Months Ended
Mar. 31, 2026
Corporate Structure and Nature of Operations Basis of Presentation
Corporate Structure and Nature of Operations; Basis of Presentation	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 made no 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 has one 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.

Corporate Structure and Nature of Operations: Basis of Presentation

3 Months Ended

Mar. 31, 2026

Corporate Structure and Nature of Operations Basis of Presentation

Corporate Structure and Nature of Operations; Basis of Presentation

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 made no 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 has one 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.