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. (Exact name of registrant as specified in its charter) Maryland 93-2560883 (State o ...

Total assets were $4.65 billion as of March 31, 2024, representing an increase of $116.6 million, or 2.6%, from December 31, 2023. NB Bancorp, Inc. Reports First Quarter 2024 Financial Results Investor Contact JP Lapointe, EVP and CFO IR@NeedhamBank.com 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 2 ...

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, INC. (Exact name of registrant as specified in its charter) Maryland 93-2560883 ...

Exhibit 99.1 NB Bancorp, Inc. Reports Full Year 2023 Financial Results Investor Contact ● Net income was $9.8 million for 2023, which was negatively impacted by the previously mentioned one-time expenses, most significantly the $19.1 million expense for the cash and stock contribution to the Needham Bank Charitable Foundation. ● Net income, excluding conversion and IPO-related expenses, was $34.3 million for the year ended December 31, 2023. ● Book value and tangible book value per share were $17.75 and $17 ...

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such requirements for the past 90 days. YES ☐ NO ☒ Indicate by check mark whether the Registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation ...