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 open-market share purchases. On March 6, 2026, he bought 5,000 shares of common stock in total, including 2,000 shares through an IRA at $20.78 per share and 3,000 shares as trustee for a trust at $20.77 per share.

Following these transactions, the IRA held 47,000 shares and the trust held 3,000 shares. Separate holding entries show 394,161 shares held directly, 49,597 shares indirectly through a 401(k), and 3,677 shares indirectly through an ESOP as of that date. Footnotes state the direct holdings include restricted stock vesting 20% per year starting April 24, 2026 and 33 1/3% per year starting February 25, 2027.

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
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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 MASSACHUSETTS 02492

(City) (State) (Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

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

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

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

4. If Amendment, Date of Original Filed (Month/Day/Year)
03/09/2026

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								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	03/20/2026
	** 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.
* Form 4: SEC 1474 (03-26)

FAQ

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

NB Bancorp reported that Joseph P. Campanelli, its President, CEO and Chairman, purchased 5,000 shares of common stock in open-market transactions. The buys occurred on March 6, 2026 and were executed through an IRA account and a trust he serves as trustee.

How many NB Bancorp (NBBK) shares did the CEO buy and at what prices?

Joseph P. Campanelli bought 5,000 NB Bancorp common shares on March 6, 2026. He purchased 2,000 shares through an IRA at $20.78 per share and 3,000 shares as trustee for a trust at $20.77 per share in open-market transactions.

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

After the trades, the IRA held 47,000 shares and the trust held 3,000 shares. Additional holding entries show 394,161 shares held directly, 49,597 shares held indirectly through a 401(k), and 3,677 shares held indirectly through an ESOP as of the transaction date.

What does the NB Bancorp (NBBK) Form 4/A disclose about the CEO’s restricted stock?

The filing notes that Campanelli’s direct holdings include restricted stock with two vesting schedules. One grant vests 20% per year starting April 24, 2026, and another vests 33 1/3% per year starting February 25, 2027, increasing his accessible shares over time.

Are the NB Bancorp (NBBK) CEO’s new share purchases direct or indirect holdings?

The newly purchased 5,000 shares are reported as indirect holdings. Specifically, 2,000 shares are held through an IRA and 3,000 shares are held in a trust for which Joseph P. Campanelli serves as trustee, according to the ownership descriptions in the filing.