NB Bancorp (NBBK) CEO adds 5,000 shares in open‑market purchases

Rhea-AI Filing Summary

NB Bancorp, Inc. President, CEO and Chairman Joseph P. Campanelli reported indirect open‑market purchases of a total of 5,000 shares of common stock on March 6, 2026. An IRA associated with him bought 2,000 shares at $20.78 per share, and a trust for which he serves as trustee bought 3,000 shares at $20.77 per share.

Following these trades, the IRA held 47,000 shares and the trust held 3,000 shares. Separate reported holdings show additional direct and indirect common stock positions, including restricted stock that vests 20% per year starting April 24, 2026 and 33 1/3% per year starting February 25, 2027.

Insider Trade Summary

Net Buyer: 5,000 shares ($103,870)

Net Buy 6 txns

Insider CAMPANELLI JOSEPH P

Role President & CEO

Bought 5,000 shs ($104K)

Type	Security	Shares	Price	Value
Purchase	Common Stock	2,000	$20.78	$42K
Purchase	Common Stock	3,000	$20.77	$62K
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 47,000 shares (Indirect, By IRA); Common Stock — 394,161 shares (Direct)

Footnotes (1)

1. Includes shares of restricted stock which vest at a rate of 20% per year commencing on April 24, 2026. Includes shares of restricted stock which vest at a rate of 33 1/3% per year commencing on February 25, 2027.

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Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

CAMPANELLI JOSEPH P

(Last) (First) (Middle)

1063 GREAT PLAIN AVE

(Street)

NEEDHAM MA 02492

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
NB Bancorp, Inc. [ NBBK ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)	X	Other (specify below)
	President & CEO		Chairman of the Board

3. Date of Earliest Transaction (Month/Day/Year)
03/06/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	03/06/2026		P		2,000	A	$20.78	47,000	I	By IRA
Common Stock	03/06/2026		P		3,000	A	$20.77	3,000	I	As trustee for trust
Common Stock								394,161(1)(2)	D
Common Stock								45,000	I	By IRA
Common Stock								49,597	I	By 401(k)
Common Stock								3,677	I	By ESOP

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Includes shares of restricted stock which vest at a rate of 20% per year commencing on April 24, 2026.

2. Includes shares of restricted stock which vest at a rate of 33 1/3% per year commencing on February 25, 2027.

	/s/ Steven Lanter, pursuant to power of attorney	03/09/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider share purchases did NB Bancorp (NBBK) report for Joseph P. Campanelli?

NB Bancorp reported that Joseph P. Campanelli indirectly bought 5,000 common shares on March 6, 2026. An IRA bought 2,000 shares at $20.78, and a trust for which he is trustee bought 3,000 shares at $20.77 in open‑market transactions.

How were Joseph P. Campanelli’s NB Bancorp (NBBK) purchases structured?

The purchases were made indirectly through entities associated with Joseph P. Campanelli. An IRA linked to him acquired 2,000 shares, while a trust for which he serves as trustee acquired 3,000 shares, all as open‑market purchases of NB Bancorp common stock.

What are Joseph P. Campanelli’s NB Bancorp (NBBK) holdings after the reported trades?

After the March 6, 2026 trades, the IRA held 47,000 NB Bancorp common shares and the trust held 3,000 shares. Additional lines report separate direct and indirect common stock positions, including shares held via a 401(k) and an ESOP arrangement.

What roles does Joseph P. Campanelli hold at NB Bancorp (NBBK)?

Joseph P. Campanelli is reported as a director, President, Chief Executive Officer and Chairman of the Board of NB Bancorp, Inc. These leadership roles make his indirect open‑market purchases of the company’s common stock particularly notable to market observers.

Do Joseph P. Campanelli’s NB Bancorp (NBBK) holdings include restricted stock?

Yes. Reported holdings include restricted NB Bancorp common stock with specific vesting schedules. Some restricted shares vest 20% each year beginning April 24, 2026, while another grant vests 33 1/3% each year starting February 25, 2027, subject to applicable conditions.

How much net insider buying did NB Bancorp (NBBK) disclose in this Form 4?

The Form 4 shows net insider buying of 5,000 NB Bancorp common shares by entities associated with Joseph P. Campanelli. There were two purchase transactions and no reported sales, resulting in a net-buy position based on the summarized transaction data.