[Form 4] NB Bancorp, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Christopher R. Lynch, a director of NB Bancorp, Inc. (NBBK), reported a non-cash disposition on 09/09/2025. The filing shows 600 shares of Common Stock were disposed of under transaction code G (a gift) at a reported price of $0. After the reported transaction, Mr. Lynch directly beneficially owns 93,762 shares and indirectly owns 60,000 shares through an IRA.

The form notes restricted stock holdings that begin vesting at 20% per year starting April 24, 2026. The Form 4 was signed by a power of attorney on behalf of the reporting person on 09/11/2025.

Positive

• Transaction identified as a Code G gift, indicating no cash proceeds and reducing potential market-sell signaling
• Clear disclosure of total beneficial ownership: 93,762 shares direct and 60,000 shares indirect (IRA)
• Restricted stock vesting schedule provided (20% per year starting April 24, 2026), clarifying future share availability

Negative

• None.

Insights

Securities Analyst

TL;DR: Routine insider gift of 600 shares; overall ownership remains substantial and unchanged materially.

The Form 4 discloses a Code G disposition of 600 shares by a director, indicating a gift rather than a market sale. The reporting person retains substantial direct ownership (93,762 shares) and indirect ownership via an IRA (60,000 shares). There is no cash proceeds event recorded and no change to derivative positions. For investors, this is a routine governance disclosure with no evident impact on company operations or capitalization.

Corporate Governance Expert

TL;DR: Compliance disclosure completed; vesting schedule noted, no red flags for governance or insider trading.

The filing appropriately identifies the reporting relationship (director) and the transaction type. The inclusion of restricted stock vesting terms (20% annually from April 24, 2026) clarifies future dilution timing for those shares. The use of a power of attorney to sign is standard. This disclosure appears procedural and consistent with Section 16 reporting obligations.

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

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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^*

Lynch Christopher R.

(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
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
09/09/2025

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	09/09/2025		G		600	D	$0	93,762(1)	D
Common Stock								60,000	I	By IRA

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.

	/s/ Steven Lanter, pursuant to power of attorney	09/11/2025
	** 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 transaction did Christopher R. Lynch report on Form 4 for NBBK?

The Form 4 reports a Code G disposition (gift) of 600 shares of NB Bancorp common stock on 09/09/2025.

How many NB Bancorp (NBBK) shares does the reporting director beneficially own after the transaction?

After the reported transaction the director beneficially owns 93,762 shares directly and 60,000 shares indirectly via an IRA.

Did the Form 4 show any cash proceeds from the reported transaction?

No. The reported price is listed as $0, consistent with a gift (Code G) rather than a sale for cash.

Is there any information on restricted stock vesting in the filing?

Yes. The filing states that included restricted shares vest at 20% per year beginning April 24, 2026.

Who signed the Form 4 filing for the reporting person?

The Form 4 was signed by Steven Lanter pursuant to power of attorney on 09/11/2025.