NBBK / NB Bancorp, Inc. - Pengajuan SECLaporan Tahunan, Pernyataan Proksi

SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant To Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended June 30, 2025 OR ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to Commission File No. 001-41899 NB Bancorp, Inc. (Exa

PROXY STATEMENT/PROSPECTUS

TABLE OF CONTENTS  Filed pursuant to Rule 424(b)(3)  Registration No. 333-288494 PROXY STATEMENT/PROSPECTUS Dear Provident Stockholders: On behalf of Provident Bancorp, Inc. (“Provident”), we are pleased to enclose the accompanying proxy statement/prospectus relating to the acquisition of Provident by NB Bancorp, Inc. (“Needham”). We are requesting that you take certain actions as a Provident stoc

3 NB Bancorp, Inc. Overview 4 Overview of NB Bancorp, Inc. NASDAQCM: NBBK Headquartered: Needham, MA IPO: December 2023; Raised ~$410M in gross proceeds Sixth largest public community bank headquartered in Massachusetts The “Builder’s Bank” with deep

Exhibit 99.1 1 July 29, 2025 KBW Investor Conference 2 Forward Looking Statements Statements in this press release that are not historical facts are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and are intended to be covered by the safe harbor provisions of the Private Sec

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): July 29, 2025 NB BANCORP, INC. (E

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): July 29, 2025 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer of

As filed with the Securities and Exchange Commission on July 28, 2025

TABLE OF CONTENTS As filed with the Securities and Exchange Commission on July 28, 2025 Registration No.

Consent of Piper Sandler & Co.

Exhibit 99.2 CONSENT OF PIPER SANDLER & CO. We hereby consent to the inclusion of our opinion letter to the Board of Directors of Provident Bancorp, Inc. (the “Company”) as an Annex B to the Proxy Statement/Prospectus relating to the proposed merger of the Company with NB Bancorp, Inc. contained in Amendment No. 1 to the Registration Statement on Form S-4, as filed with the Securities and Exchange

As of and for the three months ended

Exhibit 99.1 NB Bancorp, Inc. Reports Second Quarter 2025 Financial Results, Initiates Quarterly Cash Dividend Investor Contact JP Lapointe, EVP and CFO [email protected] 781-474-5408 Needham, MA, July 23, 2025 – NB Bancorp, Inc. (the “Company”) (Nasdaq Capital Market: NBBK), the holding company of Needham Bank (the “Bank”), today announced its second quarter 2025 financial results. The Company r

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): July 23, 2025 NB BANCORP, INC. (E

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): July 23, 2025 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer of

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): July 15, 2025 NB BANCORP, INC. (E

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): July 15, 2025 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer of

Consent of Piper Sandler & Co.

Exhibit 99.2 1251 AVENUE OF THE AMERICAS, 6TH FLOOR NEW YORK, NY 10020 P 212 466-7800 | TF 800 635-6851 Piper Sandler & Co. Since 1885. Member SIPC and NYSE. CONSENT OF PIPER SANDLER & CO. We hereby consent to the inclusion of our opinion letter to the Board of Directors of Provident Bancorp, Inc. (the “Company”) as an Annex B to the Proxy Statement/Prospectus relating to the proposed merger of th

Consent of Joseph B. Reilly (as a proposed director of NB Bancorp, Inc.)

Exhibit 99.4 CONSENT OF PROSPECTIVE DIRECTOR In accordance with Rule 438 promulgated under the Securities Act of 1933, as amended, I hereby consent to my being named in this Registration Statement on Form S-4, to which this consent is an exhibit, filed by NB Bancorp, Inc. (the “Registrant”) with the Securities and Exchange Commission, and all amendments (including post-effective amendments) theret

Form of Proxy Card of Provident Bancorp, Inc.

Exhibit 99.3 2025 1. The approval of the Agreement and Plan of Merger (the “merger agreement”), dated as of June 5, 2025, by and among NB Bancorp, Inc. (“NB Bancorp”), Needam Bank, 1828 MS, Inc., Provident Bancorp, Inc., and BankProv, and to approve the transactions contemplated by the merger agreement, including the merger (the “merger”) of 1828 MS, Inc. with and into Provident Bancorp, Inc., wit

Filing Fee Table

Exhibit 107 CALCULATION OF REGISTRATION FEE Proposed Proposed Amount Maximum Maximum Title of Each Class of to Be Offering Price Aggregate Amount of Securities to Be Registered Registered(1) per Unit Offering Price(2) Registration Fee(3) Common Stock, par value $0.

As filed with the Securities and Exchange Commission on July 2, 2025

TABLE OF CONTENTS As filed with the Securities and Exchange Commission on July 2, 2025 Registration No.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 11-K FOR ANNUAL REPORTS OF EMPLOYEE STOCK PURCHASE, SAVINGS AND SIMILAR PLANS PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 11-K FOR ANNUAL REPORTS OF EMPLOYEE STOCK PURCHASE, SAVINGS AND SIMILAR PLANS PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 [X] ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934. For the fiscal year ended December 31, 2024 OR [ ] TRANSITION REPORT PURSUANT TO SECTION 15(d) O

Agreement and Plan of Merger by and among NB Bancorp, Inc., Needham Bank, 1828 MS, Inc., Provident Bancorp, Inc., and BankProv, dated as of June 5, 2025

Exhibit 2.1 AGREEMENT AND PLAN OF MERGER DATED AS OF JUNE 5, 2025 BY AND AMONG NB BANCORP. INC., NEEDHAM BANK, 1828 MS, INC., PROVIDENT BANCORP, INC., AND BANKPROV TABLE OF CONTENTS Article I THE TRANSACTIONS‌1 Section 1.01 The Merger‌1 Section 1.02 The Holdco Merger‌2 Section 1.03 The Bank Merger‌2 Section 1.04 Closing‌2 Section 1.05 Effective Times.‌2 Section 1.06 Organizational Documents, Buyer

Change in Control Agreement with Jean-Pierre Lapointe

Exhibit 10.1 Exhibit 10.1 JP Lapointe Page 1 CHANGE IN CONTROL AGREEMENT THIS CHANGE IN CONTROL AGREEMENT (this “Agreement”) is dated this June 5, 2025, between Needham Bank, with its principal place of business in Needham, Massachusetts (the “Bank”) and Jean-Pierre Lapointe (the “Executive”). When used in this Agreement, the term “Company” shall refer to NB Bancorp, Inc., the holding company of t

NB Bancorp, Inc. and Provident Bancorp, Inc. Enter Into Definitive Merger Agreement

Exhibit 99.3 NB Bancorp, Inc. and Provident Bancorp, Inc. Enter Into Definitive Merger Agreement Key Highlights: ● Merger expands Needham Bank’s branch footprint into the North Shore of Massachusetts and New Hampshire ● The merger is expected to be approximately 19% accretive to NB Bancorp, Inc.’s earnings per share in 2026, the first full year of combined operations, assuming full phase-in of cos

VOTING AGREEMENT

Exhibit 99.1 VOTING AGREEMENT VOTING AGREEMENT (“Agreement”), dated as of June 5, 2025, by and between NB Bancorp, Inc., a Maryland corporation (“Buyer”), and the undersigned holder (the “Shareholder”) of Common Stock, par value $0.01 per share (the “Common Stock”), of Provident Bancorp., Inc., a Maryland corporation (“Company”). BACKGROUND STATEMENTS: A.Concurrently with the execution of this Agr

2 reflected in the final report that the Parties expect to be delivered to Seller prior to the Closing under the Merger Agreement (the “Final Valuation Report”), will likely be greater, and may be materially greater, than the Non-Competition Payment,

Exhibit 99.2 Exhibit 99.2 7273403 CONSULTING AGREEMENT THIS CONSULTING AGREEMENT (this “Agreement”) is made and entered into by and among NB Bancorp, Inc., Inc. (“NBBK”), Needham Bank, a wholly owned subsidiary of NBBK (“the “Bank” and, together with NBBK, the “Company”), and Joseph B. Reilly (the “Consultant”) (collectively referred to as the “Parties”), as of the 5th day of June, 2025, to become

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K/A CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): June 5, 2025 NB BANCORP, INC. (

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K/A CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): June 5, 2025 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer o

2 Disclaimer and Caution About Forward-Looking Statements CAUTION REGARDING FORWARD-LOOKING STATEMENTS This communication may contain forward-looking statements, including, but not limited to, certain plans, expectations, goals, projections, and stat

Exhibit 99.4 June 5, 2025 Merger Investor Presentation + 2 Disclaimer and Caution About Forward-Looking Statements CAUTION REGARDING FORWARD-LOOKING STATEMENTS This communication may contain forward-looking statements, including, but not limited to, certain plans, expectations, goals, projections, and statements about the benefits of the proposed transaction, the plans, objectives, expectations an

2 reflected in the final report that the Parties expect to be delivered to Seller prior to the Closing under the Merger Agreement (the “Final Valuation Report”), will likely be greater, and may be materially greater, than the Non-Competition Payment,

Exhibit 99.2 Exhibit 99.2 7273403 CONSULTING AGREEMENT THIS CONSULTING AGREEMENT (this “Agreement”) is made and entered into by and among NB Bancorp, Inc., Inc. (“NBBK”), Needham Bank, a wholly owned subsidiary of NBBK (“the “Bank” and, together with NBBK, the “Company”), and Joseph B. Reilly (the “Consultant”) (collectively referred to as the “Parties”), as of the 5th day of June, 2025, to become

Change in Control Agreement with Jean-Pierre Lapointe

Exhibit 10.1 Exhibit 10.1 JP Lapointe Page 1 CHANGE IN CONTROL AGREEMENT THIS CHANGE IN CONTROL AGREEMENT (this “Agreement”) is dated this June 5, 2025, between Needham Bank, with its principal place of business in Needham, Massachusetts (the “Bank”) and Jean-Pierre Lapointe (the “Executive”). When used in this Agreement, the term “Company” shall refer to NB Bancorp, Inc., the holding company of t

2 Disclaimer and Caution About Forward-Looking Statements CAUTION REGARDING FORWARD-LOOKING STATEMENTS This communication may contain forward-looking statements, including, but not limited to, certain plans, expectations, goals, projections, and stat

Exhibit 99.4 June 5, 2025 Merger Investor Presentation + 2 Disclaimer and Caution About Forward-Looking Statements CAUTION REGARDING FORWARD-LOOKING STATEMENTS This communication may contain forward-looking statements, including, but not limited to, certain plans, expectations, goals, projections, and statements about the benefits of the proposed transaction, the plans, objectives, expectations an

Agreement and Plan of Merger by and among NB Bancorp, Inc., Needham Bank, 1828 MS, Inc., Provident Bancorp, Inc., and BankProv, dated as of June 5, 2025

Exhibit 2.1 AGREEMENT AND PLAN OF MERGER DATED AS OF JUNE 5, 2025 BY AND AMONG NB BANCORP. INC., NEEDHAM BANK, 1828 MS, INC., PROVIDENT BANCORP, INC., AND BANKPROV TABLE OF CONTENTS Article I THE TRANSACTIONS‌1 Section 1.01 The Merger‌1 Section 1.02 The Holdco Merger‌2 Section 1.03 The Bank Merger‌2 Section 1.04 Closing‌2 Section 1.05 Effective Times.‌2 Section 1.06 Organizational Documents, Buyer

2 reflected in the final report that the Parties expect to be delivered to Seller prior to the Closing under the Merger Agreement (the “Final Valuation Report”), will likely be greater, and may be materially greater, than the Non-Competition Payment,

Exhibit 99.2 Exhibit 99.2 7273403 CONSULTING AGREEMENT THIS CONSULTING AGREEMENT (this “Agreement”) is made and entered into by and among NB Bancorp, Inc., Inc. (“NBBK”), Needham Bank, a wholly owned subsidiary of NBBK (“the “Bank” and, together with NBBK, the “Company”), and Joseph B. Reilly (the “Consultant”) (collectively referred to as the “Parties”), as of the 5th day of June, 2025, to become

Entry into a Material Definitive Agreement, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K/A CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): June 5, 2025 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer o

VOTING AGREEMENT

Exhibit 99.1 VOTING AGREEMENT VOTING AGREEMENT (“Agreement”), dated as of June 5, 2025, by and between NB Bancorp, Inc., a Maryland corporation (“Buyer”), and the undersigned holder (the “Shareholder”) of Common Stock, par value $0.01 per share (the “Common Stock”), of Provident Bancorp., Inc., a Maryland corporation (“Company”). BACKGROUND STATEMENTS: A.Concurrently with the execution of this Agr

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): June 5, 2025 NB BANCORP, INC. (Ex

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): June 5, 2025 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer of

2 Disclaimer and Caution About Forward-Looking Statements CAUTION REGARDING FORWARD-LOOKING STATEMENTS This communication may contain forward-looking statements, including, but not limited to, certain plans, expectations, goals, projections, and stat

Exhibit 99.4 June 5, 2025 Merger Investor Presentation + 2 Disclaimer and Caution About Forward-Looking Statements CAUTION REGARDING FORWARD-LOOKING STATEMENTS This communication may contain forward-looking statements, including, but not limited to, certain plans, expectations, goals, projections, and statements about the benefits of the proposed transaction, the plans, objectives, expectations an

NB Bancorp, Inc. and Provident Bancorp, Inc. Enter Into Definitive Merger Agreement

Exhibit 99.3 NB Bancorp, Inc. and Provident Bancorp, Inc. Enter Into Definitive Merger Agreement Key Highlights: ● Merger expands Needham Bank’s branch footprint into the North Shore of Massachusetts and New Hampshire ● The merger is expected to be approximately 19% accretive to NB Bancorp, Inc.’s earnings per share in 2026, the first full year of combined operations, assuming full phase-in of cos

NB Bancorp, Inc. and Provident Bancorp, Inc. Enter Into Definitive Merger Agreement

Exhibit 99.3 NB Bancorp, Inc. and Provident Bancorp, Inc. Enter Into Definitive Merger Agreement Key Highlights: ● Merger expands Needham Bank’s branch footprint into the North Shore of Massachusetts and New Hampshire ● The merger is expected to be approximately 19% accretive to NB Bancorp, Inc.’s earnings per share in 2026, the first full year of combined operations, assuming full phase-in of cos

VOTING AGREEMENT

Exhibit 99.1 VOTING AGREEMENT VOTING AGREEMENT (“Agreement”), dated as of June 5, 2025, by and between NB Bancorp, Inc., a Maryland corporation (“Buyer”), and the undersigned holder (the “Shareholder”) of Common Stock, par value $0.01 per share (the “Common Stock”), of Provident Bancorp., Inc., a Maryland corporation (“Company”). BACKGROUND STATEMENTS: A.Concurrently with the execution of this Agr

Change in Control Agreement with Jean-Pierre Lapointe

Exhibit 10.1 Exhibit 10.1 JP Lapointe Page 1 CHANGE IN CONTROL AGREEMENT THIS CHANGE IN CONTROL AGREEMENT (this “Agreement”) is dated this June 5, 2025, between Needham Bank, with its principal place of business in Needham, Massachusetts (the “Bank”) and Jean-Pierre Lapointe (the “Executive”). When used in this Agreement, the term “Company” shall refer to NB Bancorp, Inc., the holding company of t

Agreement and Plan of Merger by and among NB Bancorp, Inc., Needham Bank, 1828 MS, Inc., Provident Bancorp, Inc., and BankProv, dated as of June 5, 2025

Exhibit 2.1 AGREEMENT AND PLAN OF MERGER DATED AS OF JUNE 5, 2025 BY AND AMONG NB BANCORP. INC., NEEDHAM BANK, 1828 MS, INC., PROVIDENT BANCORP, INC., AND BANKPROV TABLE OF CONTENTS Article I THE TRANSACTIONS‌1 Section 1.01 The Merger‌1 Section 1.02 The Holdco Merger‌2 Section 1.03 The Bank Merger‌2 Section 1.04 Closing‌2 Section 1.05 Effective Times.‌2 Section 1.06 Organizational Documents, Buyer

SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant To Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended March 31, 2025 OR ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to Commission File No. 001-41899 NB Bancorp, Inc. (Ex

NB Bancorp, Inc. Announces Commencement of Additional Share Repurchase Plan

Exhibit 99.1 NB Bancorp, Inc. Announces Commencement of Additional Share Repurchase Plan Investor Contact JP Lapointe, EVP and CFO [email protected] 781-474-5408 Needham, MA, May 7, 2025 – NB Bancorp, Inc. (the “Company”) (Nasdaq Capital Market: NBBK), the holding company of Needham Bank (the “Bank”), today announced that it has adopted a stock repurchase plan for up to 2,028,522 shares of the Co

Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): May 7, 2025 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer of I

Form of Non-Qualified Stock Option Award Agreement

Exhibit 10.4 FORM OF NON-QUALIFIED STOCK OPTION AWARD AGREEMENT Granted by NB BANCORP, INC. under the NB BANCORP, INC. 2025 EQUITY INCENTIVE PLAN This Non-Qualified Stock Option Award Agreement (“Option” or “Agreement”) is and will be subject in every respect to the provisions of the NB Bancorp, Inc. 2025 Equity Incentive Plan (the “Plan”), which are incorporated herein by reference and made a par

As filed with the Securities and Exchange Commission on April 24, 2025 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-8 REGISTRATION STATEMENT THE SECURITIES ACT OF 1933 NB Bancorp, Inc. (Exact Name of Registrant as Sp

Registration No. 333- As filed with the Securities and Exchange Commission on April 24, 2025 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-8 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 NB Bancorp, Inc. (Exact Name of Registrant as Specified in its Charter) Maryland 93-2560883 (State or Other Jurisdiction of Incorporation or Organization) (I.R.S. Employe

Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): April 23, 2025 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer o

Form of Restricted Stock Award Agreement

Exhibit 10.2 FORM OF RESTRICTED STOCK AWARD AGREEMENT Granted by NB BANCORP, INC. under the NB BANCORP, INC. 2025 EQUITY INCENTIVE PLAN This Restricted Stock Award Agreement (“Restricted Stock Award” or “Agreement”) is and will be subject in every respect to the provisions of the NB Bancorp, Inc. 2025 Equity Incentive Plan (the “Plan”), which are incorporated herein by reference and made a part of

Form of Performance Restricted Stock Unit Award Agreement

Exhibit 10.5 FORM OF PERFORMANCE RESTRICTED STOCK UNIT AWARD AGREEMENT Granted by NB BANCORP, Inc. Under the NB BANCORP, INC. 2025 Equity Incentive Plan This Performance Restricted Stock Unit Award Agreement (“Performance RSUs” or “Agreement”) is and will be subject in every respect to the provisions of the NB Bancorp, Inc. 2025 Equity Incentive Plan (the “Plan”), which are incorporated herein by

Form of Incentive Stock Option Award Agreement

Exhibit 10.3 FORM OF INCENTIVE STOCK OPTION AWARD AGREEMENT Granted by NB BANCORP, INC. under the NB BANCORP, INC. 2025 EQUITY INCENTIVE PLAN This Incentive Stock Option Award Agreement (“Option” or “Agreement”) is and will be subject in every respect to the provisions of the NB Bancorp, Inc. 2025 Equity Incentive Plan (the “Plan”), which are incorporated herein by reference and made a part of thi

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-8 (Form Type) NB Bancorp, Inc.

As of and for the three months ended

Exhibit 99.1 NB Bancorp, Inc. Reports First Quarter 2025 Financial Results Investor Contact JP Lapointe, EVP and CFO [email protected] 781-474-5408 Needham, MA, April 22, 2025 – NB Bancorp, Inc. (the “Company”) (Nasdaq Capital Market: NBBK), the holding company of Needham Bank (the “Bank”), today announced its first quarter 2025 financial results. The Company reported net income of $12.7 million,

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): April 22, 2025 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer o

Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): March 28, 2025 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer o

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐Preliminary Proxy Statement ☐Confidential, for Use of the Commission Only (as permitted

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the year ended December 31, 2024. OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to . Commission file number: 001-41899 NB BANCORP,

Insider Trading Policy and Procedures

Exhibit 19 Policy Regarding Insider Trading Introduction NB Bancorp, Inc. (the “Company”) is a public company registered with the Securities and Exchange Commission (the “SEC”) that has issued common stock listed and traded on the Nasdaq exchange under the Nasdaq Capital Market as securities (collectively, the “Securities”). As a public company, the Company files annual, quarterly and periodic rep

JOINT FILING AGREEMENT

EX-99 2 d11604640ex-99a.htm Exhibit A JOINT FILING AGREEMENT The undersigned agree that this Schedule 13G Amendment No. 1 dated February 12, 2025 relating to the Common Stock, par value $0.01 per share, of NB Bancorp, Inc. shall be filed on behalf of the undersigned. PERTENTO PARTNERS LLP By: /s/ Eduardo Marques Name: Eduardo Marques Title: Managing Partner EDUARDO MARQUES By: /s/ Eduardo Marques

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): January 28, 2025 NB Bancorp, Inc. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction of Incorporation) (Commission File No.)

NEEDHAM BANK THIRD AMENDMENT TO SECOND AMENDED AND RESTATED DIRECTOR RETIREMENT PLAN

Exhibit 10.1 NEEDHAM BANK THIRD AMENDMENT TO SECOND AMENDED AND RESTATED DIRECTOR RETIREMENT PLAN WHEREAS, Needham Bank (hereinafter referred to as the “Bank”) previously established the Needham Bank Second Amended and Restated Director Retirement Plan, effective July 18, 2013 (the “Director Retirement Plan”), as amended by the First Amendment to the Second Amended and Restated Director Retirement

NEEDHAM BANK FIRST AMENDMENT TO NEEDHAM BANK NONQUALIFIED DEFERRED COMPENSATION PLAN FOR OFFICERS

Exhibit 10.2 NEEDHAM BANK FIRST AMENDMENT TO NEEDHAM BANK NONQUALIFIED DEFERRED COMPENSATION PLAN FOR OFFICERS WHEREAS, Needham Bank (hereinafter referred to as “Bank”) previously established the Needham Bank Nonqualified Deferred Compensation Plan for Officers, effective April 1, 2013 (the “Plan”), for a select group of management or highly compensated employees; and WHEREAS, the Bank desires to

3 NB Bancorp, Inc. Overview 4 Overview of NB Bancorp, Inc. NASDAQCM: NBBK Headquartered: Needham, MA IPO: December 2023; Raised ~$410M in gross proceeds Sixth largest public community bank headquartered in Massachusetts The “Builder’s Bank” with deep

Exhibit 99.1 1 January 29, 2025 Janney Investor Conference 2 Forward Looking Statements Statements in this presentation that are not historical facts are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and are intended to be covered by the safe harbor provisions of the Privat

Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): January 29, 2025 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer

As of and for the three months ended

NB Bancorp, Inc. Reports Fourth Quarter 2024 Financial Results and Announces Commencement of Share Repurchase Plan Investor Contact JP Lapointe, EVP and CFO [email protected] 781-474-5408 Needham, MA, January 22, 2025 – NB Bancorp, Inc. (the “Company”) (Nasdaq Capital Market: NBBK), the holding company of Needham Bank (the “Bank”), today announced its fourth quarter 2024 financial results. The Co

Financial Statements and Exhibits, Results of Operations and Financial Condition, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): January 22, 2025 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer

NB Bancorp, Inc. Names Christine Roberts Executive Vice President and Chief Operating Officer

FOR IMMEDIATE RELEASE Contact: Karen Marryat SVP/ Chief Marketing OfficerTelephone: (781) 474-5460 NB Bancorp, Inc.

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): January 3, 2025 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer

Change in Control Agreement with Christine Roberts

Exhibit 10.1 18 Months CHANGE IN CONTROL AGREEMENT THIS CHANGE IN CONTROL AGREEMENT (this “Agreement”) is dated this sixth of January 2025, between Needham Bank, with its principal place of business in Needham, Massachusetts (the “Bank”) and Christine Roberts (the “Executive”). When used in this Agreement, the term “Company” shall refer to NB Bancorp, Inc., the holding company of the Bank. WITNESS

NBBK / NB Bancorp, Inc. / PRINCIPAL FINANCIAL GROUP INC - 13G NB BANCORP INC. 093024 Passive Investment

SC 13G 1 a13gnbbancorpinc093024.htm 13G NB BANCORP INC. 093024 CUSIP No. 63945M107 13G Page 1 of 5 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G* Under the Securities Exchange Act of 1934 NB Bancorp Inc (Name of Issuer) Common Stock, par value $0.01 per share (Title of Class of Securities) 63945M107 (CUSIP Number) September 30, 2024 (Date of Event Which Requi

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): November 14, 2024 NB BANCORP, INC

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): November 14, 2024 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employe

3 NB Bancorp, Inc. Overview 4 Overview of NB Bancorp, Inc. NASDAQCM: NBBK Headquartered: Needham, MA IPO: December 2023; Raised ~$410M in gross proceeds Sixth largest public community bank headquartered in Massachusetts The “Builder’s Bank” with deep

Exhibit 99.1 1 November 14, 2024 Piper Sandler Investor Conference 2 Forward Looking Statements Statements in this presentation that are not historical facts are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and are intended to be covered by the safe harbor provisions of th

SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant To Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended September 30, 2024 OR ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to Commission File No. 001-41899 NB Bancorp, Inc.

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): October 30, 2024 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer

As of and for the three months ended

NB Bancorp, Inc. Reports Third Quarter 2024 Financial Results Investor Contact JP Lapointe, EVP and CFO [email protected] 781-474-5408 Needham, MA, October 30, 2024 – NB Bancorp, Inc. (the “Company”) (Nasdaq Capital Market: NBBK), the holding company of Needham Bank (the “Bank”), today announced its third quarter 2024 financial results. SELECTED FINANCIAL HIGHLIGHTS FOR THE THIRD QUARTER OF 2024

NB Bancorp, Inc. Appoints New Board Member and Lead Independent Director

Exhibit 99.1 Media Contact: Karen Marryat SVP/Chief Marketing Officer 781-474-5460 [email protected] FOR IMMEDIATE RELEASE: NB Bancorp, Inc. Appoints New Board Member and Lead Independent Director NEEDHAM, MA, September 12, 2024 – NB Bancorp, Inc. (the “Company”) is pleased to announce that Kenneth C. Montgomery has been elected to the Board of Directors of both the Company and its subsidia

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): September 12, 2024 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employ

SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant To Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended June 30, 2024 OR ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to Commission File No. 001-41899 NB Bancorp, Inc. (Exa

3 NB Bancorp, Inc. Overview 4 Overview of NB Bancorp, Inc. NASDAQCM: NBBK Headquartered: Needham, MA IPO: December 2023; Raised ~$410M in gross proceeds Seventh largest public bank headquartered in Massachusetts The “Builder’s Bank” with deep communi

Exhibit 99.1 1 KBW Investor Conference July 30, 2024 2 Forward Looking Statements Statements in this presentation that are not historical facts are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and are intended to be covered by the safe harbor provisions of the Private Secu

Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): July 30, 2024 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer of

As of and for the three months ended

NB Bancorp, Inc. Reports Second Quarter 2024 Financial Results Investor Contact JP Lapointe, EVP and CFO [email protected] 781-474-5408 Needham, MA, July 24, 2024 – NB Bancorp, Inc. (the “Company”) (Nasdaq Capital Market: NBBK), the holding company of Needham Bank, today announced its second quarter 2024 financial results. SELECTED FINANCIAL HIGHLIGHTS FOR THE SECOND QUARTER OF 2024 ● Net income

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): July 24, 2024 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer of

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 11-K FOR ANNUAL REPORTS OF EMPLOYEE STOCK PURCHASE, SAVINGS AND SIMILAR PLANS PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 11-K FOR ANNUAL REPORTS OF EMPLOYEE STOCK PURCHASE, SAVINGS AND SIMILAR PLANS PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 [X] ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934. For the fiscal year ended December 31, 2023 OR [ ] TRANSITION REPORT PURSUANT TO SECTION 15(d) O

Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): June 4, 2024 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer of

3 NB Bancorp, Inc. Overview 4 Overview of NB Bancorp, Inc. NASDAQCM: NBBK Headquartered: Needham, MA IPO: December 2023; Raised ~$410M in gross proceeds Seventh largest public bank headquartered in Massachusetts The “Builder’s Bank” with deep communi

Exhibit 99.1 1 Investor Presentation June 4, 2024 2 Forward Looking Statements Statements in this presentation that are not historical facts are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and are intended to be covered by the safe harbor provisions of the Private Securit

Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): May 22, 2024 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer of

NBBK / NB Bancorp, Inc. / Pertento Partners LLP Passive Investment

SC 13G 1 d1105320313g.htm UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )* NB Bancorp, Inc. (Name of Issuer) Common Stock, par value $0.01 per share (Title of Class of Securities) 63945M107 (CUSIP Number) May 14, 2024 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to des

SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant To Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended March 31, 2024 OR ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to Commission File No. 001-41899 NB Bancorp, Inc. (Ex

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): April 24, 2024 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer o

As of and for the three months ended

NB Bancorp, Inc. Reports First Quarter 2024 Financial Results Investor Contact JP Lapointe, EVP and CFO [email protected] 781-474-5408 Needham, MA, April 24, 2024 – NB Bancorp, Inc. (the “Company”) (Nasdaq Capital Market: NBBK), the holding company of Needham Bank, today announced its first quarter 2024 financial results. SELECTED FINANCIAL HIGHLIGHTS FOR THE FIRST QUARTER OF 2024 ● Net income of

SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.

SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.

NB Bancorp, Inc. Clawback Policy

Exhibit 97 NB BANCORP, INC. CLAWBACK POLICY The Board of Directors (the “Board”) of NB Bancorp, Inc. (the “Company”) believes that it is in the best interests of the Company and its shareholders to adopt this Clawback Policy (this “Policy”), which provides for the recovery of Erroneously Awarded Compensation in the event the Company is required to prepare an Accounting Restatement. This Policy sha

Change in Control Agreement between Needham Bank and Margaret Watson

CHANGE IN CONTROL AGREEMENT THIS CHANGE IN CONTROL AGREEMENT (this “Agreement”) is dated this fifth day of January, 2024, between Needham Bank, with its principal place of business in Needham, Massachusetts (the “Bank”) and Margaret Watson (the “Executive”).

Description of NB Bancorp, Inc. Common Stock

Exhibit 4.2 Description of NB Bancorp, Inc. Common Stock Unless otherwise indicated or the context otherwise requires, references in this Exhibit 4.2 to “we, “us” and “our” refer collectively to NB Bancorp, Inc. and Needham Bank or to any of those entities, depending on the context. General NB Bancorp, Inc. (“NB Bancorp”) is authorized to issue 120,000,000 shares of common stock, par value of $0.0

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the year ended December 31, 2023. OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to . Commission file number: 001-41899 NB BANCORP,

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): February 28, 2024 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employe

December 31, 2023

Exhibit 99.1 NB Bancorp, Inc. Reports Full Year 2023 Financial Results Investor Contact JP Lapointe, EVP and CFO [email protected] 781-474-5408 Needham, MA, February 28, 2024 – NB Bancorp, Inc. (the “Company”) (Nasdaq Capital Market: NBBK), the holding company of Needham Bank, today announced its 2023 financial results. Concurrent with its mutual-to-stock conversion and as described in the prospe

NB Bancorp, Inc. Names JP Lapointe Executive Vice President and Chief Financial Officer

Exhibit 99.1 FOR IMMEDIATE RELEASE Contact: Karen Marryat SVP/ Chief Marketing Officer Telephone: (781) 474-5460 NB Bancorp, Inc. Names JP Lapointe Executive Vice President and Chief Financial Officer Needham, Massachusetts, February 6, 2024. NB Bancorp, Inc., the holding company for Needham Bank, has announced that Jean-Pierre (“JP”) Lapointe has been named executive vice president and chief fina

Change in Control Agreement with JP Lapointe (2)

Exhibit 10.1 18 Months CHANGE IN CONTROL AGREEMENT THIS CHANGE IN CONTROL AGREEMENT (this “Agreement”) is dated this first day of February, 2024, between Needham Bank, with its principal place of business in Needham, Massachusetts (the “Bank”) and Jean-Pierre (JP) Lapointe (the “Executive”). When used in this Agreement, the term “Company” shall refer to NB Bancorp, Inc., the holding company of the

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): February 1, 2024 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employer

Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): December 27, 2023 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 001-41899 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employe

NB Bancorp, Inc. Completes Initial Public Offering

EXHIBIT 99 FOR IMMEDIATE RELEASE Contact: Karen Marryat SVP/Chief Marketing Officer Telephone: (781) 474-5460 NB Bancorp, Inc.

Filing Fee Table

EXHIBIT 107 Calculation of Filing Fee Tables Form S-8 (Form Type) NB Bancorp, Inc.

Registration Statement on Form 8-A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 NB Bancorp, Inc. (Exact Name of Registrant as Specified in Its Charter) Maryland 93-2560883 (State or other jurisdiction of incorporation or organization) (I.R.S. Employer Identification No.) 1063

As filed with the Securities and Exchange Commission on December 27, 2023 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-8 REGISTRATION STATEMENT THE SECURITIES ACT OF 1933 NB Bancorp, Inc. (Exact Name of Registrant as

Registration No. 333- As filed with the Securities and Exchange Commission on December 27, 2023 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-8 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 NB Bancorp, Inc. (Exact Name of Registrant as Specified in its Charter) Maryland 93-2560883 (State or Other Jurisdiction of Incorporation or Organization) (I.R.S. Empl

NB Bancorp, Inc. Announces Expected Conversion Closing Date and Stock Offering Results

Exhibit 99 FOR IMMEDIATE RELEASE Contact: Karen Marryat SVP/ Chief Marketing Officer Telephone: (781) 474-5460 NB Bancorp, Inc.

Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): December 21, 2023 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 333-272567 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employ

SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q

Table of Contents SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ Quarterly Report Pursuant To Section 13 or 15(d) of the Securities Exchange Act of 1934 For the quarterly period ended September 30, 2023 OR ☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 For the transition period from to Commission File No. 333-272567 NB Bancorp, Inc

(Proposed Holding Company for Needham Bank) Up to 35,650,000 shares of Common Stock (Subject to increase to up to 40,997,500 shares)

Filed Pursuant to Rule 424(b)(3) Registration No. 333-272567 SUBSCRIPTION AND COMMUNITY OFFERING PROSPECTUS (Proposed Holding Company for Needham Bank) Up to 35,650,000 shares of Common Stock (Subject to increase to up to 40,997,500 shares) NB Bancorp, Inc., a newly formed Maryland corporation, and the proposed holding company for Needham Bank, is offering shares of common stock for sale in connec

Interests in NEEDHAM BANK 401(k) PLAN Offering of Participation Interests of up to 4,960,975 Shares of NB BANCORP, INC. Common Stock

Filed Pursuant to Rule 424(b)(3) Registration No. 333-272567 Prospectus Supplement Interests in NEEDHAM BANK 401(k) PLAN Offering of Participation Interests of up to 4,960,975 Shares of NB BANCORP, INC. Common Stock In connection with the mutual to stock conversion of NB Financial, MHC, NB Bancorp, Inc., a newly-formed Maryland corporation and the to be holding company of Needham Bank, is offering

Agency Agreement dated October 12, 2023

Exhibit 1.1 Up to 35,650,000 Shares (Subject to increase to up to 40,997,500 shares) NB BANCORP, INC. (a Maryland corporation) Common Stock (par value $0.01 per share) AGENCY AGREEMENT October 12, 2023 Piper Sandler & Co. 1251 Avenue of the Americas, 6th Floor New York, New York 10020 Ladies and Gentlemen: NB Bancorp, Inc., a newly formed Maryland corporation (the “Company”), NB Financial, Inc., a

Entry into a Material Definitive Agreement, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): October 12, 2023 NB BANCORP, INC. (Exact Name of Registrant as Specified in Charter) Maryland 333- 272567 93-2560883 (State or Other Jurisdiction) (Commission File No.) (I.R.S. Employ

NB Bancorp, Inc. 1063 Great Plain Avenue Needham, Massachusetts 02492

NB Bancorp, Inc. 1063 Great Plain Avenue Needham, Massachusetts 02492 October 10, 2023 Via Edgar Securities and Exchange Commission 100 F Street, N.E. Washington, D.C. 20549 Re: NB Bancorp, Inc. Registration Statement on Form S-1 (Registration Number 333-272567) Request for Acceleration of Effectiveness Ladies and Gentlemen: NB Bancorp, Inc., a Maryland corporation (the “Company”), hereby requests

October 10, 2023

October 10, 2023 Via Edgar Securities and Exchange Commission 100 F Street, N.E. Washington, D.C. 20549 Re: NB Bancorp, Inc. Registration Statement on Form S-1 (Registration Number 333- 272567) Request for Acceleration of Effectiveness Ladies and Gentlemen: In accordance with Rule 461 of Regulation C promulgated under the Securities Act of 1933, we hereby join NB Bancorp, Inc. in requesting that t

Filing fees exhibit

Exhibit 107 Calculation of Filing Fee Tables Form S-1 (Form Type) NB Bancorp, Inc.

As filed with the Securities and Exchange Commission on October 10, 2023

As filed with the Securities and Exchange Commission on October 10, 2023 Registration No.

Filing fees exhibit

Exhibit 107 Calculation of Filing Fee Tables Form S-1 (Form Type) NB Bancorp, Inc.

As filed with the Securities and Exchange Commission on October 2, 2023

As filed with the Securities and Exchange Commission on October 2, 2023 Registration No.

Filing fees exhibit

Exhibit 107 Calculation of Filing Fee Tables Form S-1 (Form Type) NB Bancorp, Inc.

As filed with the Securities and Exchange Commission on September 29, 2023

As filed with the Securities and Exchange Commission on September 29, 2023 Registration No.

Update to Appraisal Report of RP Financial, LC.*

Exhibit 99.7 PRO FORMA VALUATION UPDATE REPORT STANDARD CONVERSION NB Bancorp, Inc. │Needham, Massachusetts HOLDING COMPANY FOR: Needham Bank │Needham, Massachusetts Dated as of August 25, 2023 1311-A Dolley Madison Boulevard, Suite 2A McLean, Virginia 22101 703.528.1700 rpfinancial.com August 25, 2023 Board of Directors NB Financial, MHC NB Financial, Inc. Needham Bank 1063 Great Plain Avenue Nee

Form of Agency Agreement among NB Bancorp, Inc., NB Financial, MHC, NB Financial, Inc., Needham Bank and Piper Sandler & Co.*

Exhibit 1.3 Up to 35,650,000 Shares (Subject to increase to up to 40,997,500 shares) NB BANCORP, INC. (a Maryland corporation) Common Stock (par value $0.01 per share) AGENCY AGREEMENT [], 2023 Piper Sandler & Co. 1251 Avenue of the Americas, 6th Floor New York, New York 10020 Ladies and Gentlemen: NB Bancorp, Inc., a newly formed Maryland corporation (the “Company”), NB Financial, Inc., a Massach

Filing fees exhibit

Exhibit 107 Calculation of Filing Fee Tables Form S-1 (Form Type) NB Bancorp, Inc.

As filed with the Securities and Exchange Commission on September 1, 2023

As filed with the Securities and Exchange Commission on September 1, 2023 Registration No.

As filed with the Securities and Exchange Commission on August 8, 2023

As filed with the Securities and Exchange Commission on August 8, 2023 Registration No.

Filing fees exhibit

EX-FILINGFEES Calculation of Filing Fee Tables Form S-1 (Form Type) NB Bancorp, Inc.

LUSE GORMAN, PC ATTORNEYS AT LAW 5335 WISCONSIN AVENUE, N.W., SUITE 780 WASHINGTON, D.C. 20015 TELEPHONE (202) 274-2000 FACSIMILE (202) 362-2902

LUSE GORMAN, PC ATTORNEYS AT LAW 5335 WISCONSIN AVENUE, N.W., SUITE 780 WASHINGTON, D.C. 20015 TELEPHONE (202) 274-2000 FACSIMILE (202) 362-2902 www.LuseLaw.com WRITER’S DIRECT DIAL NUMBER WRITER’S E-MAIL (202) 274-2004 [email protected] August 8, 2023 Via EDGAR Securities and Exchange Commission Division of Corporation Finance Washington, D.C. 20549-3561 Attn: Ms. Aisha Adegbuyi, Staff Attorney

Form of Agency Agreement among NB Bancorp, Inc., NB Financial, MHC, NB Financial, Inc., Needham Bank and Piper Sandler & Co.

Exhibit 1.3 Up to 34,500,000 Shares (Subject to increase to up to 39,675,000 shares) NB BANCORP, INC. (a Maryland corporation) Common Stock (par value $0.01 per share) AGENCY AGREEMENT August [], 2023 Piper Sandler & Co. 1251 Avenue of the Americas, 6th Floor New York, New York 10020 Ladies and Gentlemen: NB Bancorp, Inc., a newly formed Maryland corporation (the “Company”), NB Financial, Inc., a

Engagement Letter between NB Financial, Inc. and Piper Sandler & Co. (Marketing Agent Services)*

Exhibit 1.1 1251 AVENUE OF THE AMERICAS, 6TH FLOOR NEW YORK, NY 10020 P 212 466-7800 | TF 800 635-6851 Piper Sandler & Co. Since 1985. Member SIPC and NYSE. March 20, 2023 Board of Directors NB Financial, MHC NB Financial Inc. Needham Bank 1063 Great Plain Avenue Needham, MA 02492 Attention: Mr. Joseph P. Campanelli President and Chief Executive Officer Ladies and Gentlemen: Piper Sandler & Co. (“

Stock Order and Certification Form*

Exhibit 99.5 Subscription & Community Offering Stock Order Form STOCK ORDER DEADLINE day, [Expiration Date] at :00 p.m. Eastern Time (Received not postmarked) STOCK ORDER DELIVERY If By Hand Delivery (Drop Box) Needham Bank 1063 Great Plain Avenue, Needham, MA 02492 STOCK ORDER DELIVERY If By Overnight Delivery Needham Bank Stock Order Return 575 Jericho Tpke., Ste. 101, Jericho, NY 11753 (xxx) xx

Marketing Materials*

Exhibit 99.4 NBI-F Dear Depositors and Friends of Needham Bank: We are pleased to announce that the boards of directors of Needham Bank, NB Financial, Inc., NB Bancorp, Inc., and NB Financial, MHC and depositors of Needham Bank have approved a plan of conversion under which NB Financial, MHC will convert from a mutual holding company to a stock holding company form of organization. Upon completion

LUSE GORMAN, PC ATTORNEYS AT LAW 5335 WISCONSIN AVENUE, N.W., SUITE 780 WASHINGTON, D.C. 20015 TELEPHONE (202) 274-2000 FACSIMILE (202) 362-2902

LUSE GORMAN, PC ATTORNEYS AT LAW 5335 WISCONSIN AVENUE, N.W., SUITE 780 WASHINGTON, D.C. 20015 TELEPHONE (202) 274-2000 FACSIMILE (202) 362-2902 www.LuseLaw.com WRITER’S DIRECT DIAL NUMBER WRITER’S E-MAIL (202) 274-2004 [email protected] July 27, 2023 Via EDGAR Securities and Exchange Commission Division of Corporation Finance Washington, D.C. 20549-3561 Attn: Ms. Aisha Adegbuyi, Staff Attorney

Engagement Letter between NB Financial, Inc. and Piper Sandler & Co. (Stock Information Center Manager Services)*

Exhibit 1.2 1251 AVENUE OF THE AMERICAS, 6TH FLOOR NEW YORK, NY 10020 P 212 466-7800 | TF 800 635-6851 Piper Sandler & Co. Since 1985. Member SIPC and NYSE. March 20, 2023 Board of Directors NB Financial, MHC NB Financial Inc. Needham Bank 1063 Great Plain Avenue Needham, MA 02492 Attention: Mr. Joseph P. Campanelli President and Chief Executive Officer Ladies and Gentlemen: Piper Sandler & Co. (“

Filing fees exhibit

EX-FILINGFEES Calculation of Filing Fee Tables Form S-1 (Form Type) NB Bancorp, Inc.

As filed with the Securities and Exchange Commission on July 27, 2023

As filed with the Securities and Exchange Commission on July 27, 2023 Registration No.

Letter from G.T. Reilly with respect to change in accountants*

Exhibit 16 June 8, 2023 Office of the Chief Accountant SECPS Letter File Securities and Exchange Commission SECPSletters@sec.

As filed with the Securities and Exchange Commission on June 9, 2023

As filed with the Securities and Exchange Commission on June 9, 2023 Registration No.

Engagement Letter between NB Financial, Inc. and Piper Sandler & Co. (Marketing Agent Services)

Exhibit 1.1 March 20, 2023 1251 AVENUE OF THE AMERICAS, 6TH FLOOR NEW YORK, NY 10020 P 212 466-7800 | TF 800 635-6851 Piper Sandler & Co. Since 1985. Member SIPC and NYSE. Board of Directors NB Financial, MHC NB Financial Inc. Needham Bank 1063 Great Plain Avenue Needham, MA 02492 Attention: Mr. Joseph P. Campanelli President and Chief Executive Officer Ladies and Gentlemen: Piper Sandler & Co. (“

Plan of Conversion*

Exhibit 2 NB FINANCIAL, MHC PLAN OF CONVERSION Adopted by the Board of Directors on June 7, 2023 TABLE OF CONTENTS ARTICLE 1.

Articles of Incorporation of NB Bancorp, Inc.*

Exhibit 3.1 ARTICLES OF INCORPORATION NB BANCORP, INC. The undersigned, Joseph P. Campanelli, whose address is 1063 Great Plain Avenue, Needham, Massachusetts 02492, being at least eighteen years of age, acting as incorporator, does hereby form a corporation under the general laws of the State of Maryland, having the following Articles of Incorporation (the “Articles”): ARTICLE 1. Name. The name o

Appraisal Report of RP Financial, LC.*

Exhibit 99.3 PRO FORMA VALUATION REPORT STANDARD CONVERSION NB Bancorp, Inc. │Needham, Massachusetts HOLDING COMPANY FOR: Needham Bank │Needham, Massachusetts Dated as of May 19, 2023 1311-A Dolley Madison Boulevard, Suite 2A McLean, Virginia 22101 703.528.1700 rpfinancial.com May 19, 2023 Board of Directors NB Financial, MHC NB Financial, Inc. Needham Bank 1063 Great Plain Avenue Needham, Massach

Engagement Letter between NB Financial, Inc. and Piper Sandler & Co. (Stock Information Center Manager Services)

Exhibit 1.2 1251 AVENUE OF THE AMERICAS, 6TH FLOOR NEW YORK, NY 10020 P 212 466-7800 | TF 800 635-6851 Piper Sandler & Co. Since 1985. Member SIPC and NYSE. March 20, 2023 Board of Directors NB Financial Inc. 1063 Great Plain Avenue Needham, MA 02492 Attention: Mr. Joseph P. Campanelli President and Chief Executive Officer Ladies and Gentlemen: Piper Sandler & Co. (“Piper Sandler”) understands tha

Bylaws of NB Bancorp, Inc.*

Exhibit 3.2 NB BANCORP, INC. BYLAWS ARTICLE I STOCKHOLDERS Section 1. Annual Meeting. The Corporation shall hold an annual meeting of its stockholders to elect directors and to transact any other business within its powers, at such place, on such date and at such time as the Board of Directors shall fix. Failure to hold an annual meeting does not invalidate the Corporation’s existence or affect an

Needham Bank Amended and Restated Director Retirement Plan*

Exhibit 10.7 NEEDHAM BANK SECOND AMENDED AND RESTATED DIRECTOR RETIREMENT PLAN THIS SECOND AMENDED AND RESTATED DIRECTOR RETIREMENT PLAN (the “Plan”) is hereby adopted, effective as of the 18th day of July, 2013, by the Board of Directors (“Board”) of Needham Bank (the “Bank”). WHEREAS, the Bank previously established the Director Retirement Plan, effective April 1, 2006 (the “2006 Plan”) in order

Needham Bank Non-Qualified Deferred Compensation Plan for Officers*

Exhibit 10.5 NON-QUALIFIED DEFERRED COMPENSATION PLAN FOR OFFICERS OF NEEDHAM BANK This Non-Qualified Deferred Compensation Plan for Officers of Needham Bank (the “Plan”) is effective April 1, 2013. This Plan is adopted by NEEDHAM BANK (the “Bank”) for the benefit of certain officers (“Executive” or “Executives”), who have been selected and approved by the Bank to participate in this Plan and who

Subsidiaries of NB Bancorp, Inc.*

Exhibit 21 Subsidiaries of the Registrant The following is a list of the subsidiaries of NB Bancorp, Inc.: Name State of Incorporation Needham Bank Massachusetts Needco-op Investment Corporation, Inc.(1) Massachusetts Easton Square Realty LLC (1) Massachusetts 1892 Investments LLC (1) Massachusetts (1) Wholly owned subsidiary of Needham Bank

Form of Common Stock Certificate of NB Bancorp, Inc.*

Exhibit 4 NB BANCORP, INC. No. INCORPORATED UNDER THE LAWS OF THE STATE OF MARYLAND CUSIP: THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO RESTRICTIONS, SEE REVERSE SIDE THIS CERTIFIES that is the owner of FULLY-PAID AND NON-ASSESSABLE SHARES OF COMMON STOCK, PAR VALUE $0.01 PER SHARE The shares evidenced by this certificate are transferable only on the books of NB Bancorp, Inc. by the h

Letter of RP Financial, LC. with respect to value of subscription rights*

Exhibit 99.2 June 9, 2023 NB Financial, MHC NB Financial, Inc. Needham Bank 1063 Great Plain Avenue Needham, Massachusetts 02149 Re: Plan of Conversion NB Bancorp, Inc. Needham Bank Members of the Boards of Directors: All capitalized terms not otherwise defined in this letter have the meanings given such terms in the Plan of Conversion (the “Plan”) adopted by the Boards of Directors of NB Financia

Filing fees exhibit

EX-FILINGFEES Calculation of Filing Fee Tables Form S-1 (Form Type) NB Bancorp, Inc.

Employment Agreement between Needham Bank and Salvatore Rinaldi*

Exhibit 10.2   EMPLOYMENT AGREEMENT   This Employment Agreement (the “Agreement”) is made and entered into, by and among Needham Bank, a mutual cooperative bank having its principal place of business in Needham, Massachusetts (the “Bank”), and Salvatore Rinaldi, of Woodbridge, Connecticut (the “Executive;” collectively, the Bank and the Executive are the “Parties” or a “Party”) effective as of the

Engagement letter between NB Financial, MHC, NB Financial, Inc., Needham Bank and RP Financial, LC. with respect to independent appraisal services*

Exhibit 99.1 March 14, 2023 Mr. Joseph P. Campanelli President and Chief Executive Officer Needham Bank, subsidiary of NB Financial, Inc. which is a subsidiary of NB Financial MHC 1063 Great Plain Avenue Needham, Massachusetts 02149 Dear Mr. Campanelli: This letter sets forth the agreement between Needham Bank, Needham, Massachusetts (the “Bank”), a state-chartered co-operative bank wholly owned b

Letter of RP Financial, LC. with respect to Liquidation Rights*

Exhibit 99.6 June 9, 2023 NB Financial, MHC NB Financial, Inc. Needham Bank 1063 Great Plain Avenue Needham, Massachusetts 02149 Re: Plan of Conversion NB Financial, MHC NB Bancorp, Inc. Needham Bank Members of the Boards of Directors: All capitalized terms not otherwise defined in this letter have the meanings given such terms in the Plan of Conversion (the “Plan”) adopted by the Boards of Direct

Needham Bank Nonqualified Deferred Compensation Plan*

Exhibit 10.4 NEEDHAM BANK Nonqualified Deferred Compensation Plan This document is drafted with the intent that it complies with Internal Revenue Code Section 409A and regulations promulgated thereunder. NFP Executive Benefits has provided you this specimen document strictly in its capacity as an employee benefits consulting firm and plan recordkeeper. NFP Executive Benefits does NOT provide legal

Employment Agreement between Needham Bank and Joseph P. Campanelli*

Exhibit 10.1   EMPLOYMENT AGREEMENT   This Employment Agreement (the “Agreement”) is made and entered into, by and among Needham Bank, a mutual cooperative bank having its principal place of business in Needham, Massachusetts (the “Bank”), and Joseph Campanelli, of Wellesley, Massachusetts (the “Executive;” collectively, the Bank and the Executive are the “Parties” or a “Party”) effective as of th

Needham Bank Long-Term Incentive Plan*

Exhibit 10.6 Needham Bank Long-term Incentive Plan Effective January 1, 2020 TABLE OF CONTENTS Section Page I. Plan Purposes 1 II. Compensation Philosophy 1 III. Definitions of Key Terms 1 IV. Participation 1 V. Plan Concept and Operating Guidelines 2 a.  Plan Description b.  Individual and Corporate Performance Contingencies VI. Award Opportunities for Participating Executives 2 a. Types of Award

Form of Change in Control Agreement between Needham Bank and certain executive officers*

Exhibit 10.3 CHANGE IN CONTROL AGREEMENT THIS CHANGE IN CONTROL AGREEMENT (this “Agreement”) is dated this day of , 2023, between Needham Bank, with its principal place of business in Needham, Massachusetts (the “Bank”) and [name] (the “Executive”). When used in this Agreement, the term “Company” shall refer to NB Bancorp, Inc., the holding company of the Bank. WITNESSETH WHEREAS, the Executive is