NB Bancorp (NBBK) SEVP and COO logs tax-withholding share disposition

Rhea-AI Filing Summary

NB Bancorp, Inc. Senior Executive Vice President and Chief Operating Officer Christine Roberts reported a tax-related share disposition on Common Stock. On April 24, 2026, 3,589 shares were used to satisfy tax obligations at a price of $19.82 per share, a non–open-market event. After this withholding, she holds 71,081 shares directly, 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

1 transaction reported

Mixed 1 txn

Insider Roberts Christine

Role SEVP and COO

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock	3,589	$19.82	$71K

Holdings After Transaction: Common Stock — 71,081 shares (Direct, null)

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.

Key Figures

Tax-withholding shares: 3,589 shares Tax-withholding price: $19.82 per share Post-transaction holdings: 71,081 shares +2 more

5 metrics

Tax-withholding shares 3,589 shares Common Stock delivered for tax obligations on April 24, 2026

Tax-withholding price $19.82 per share Valuation used for the 3,589 withheld shares

Post-transaction holdings 71,081 shares Total Common Stock held directly after April 24, 2026 transaction

Restricted stock vesting 20% annually 20% per year Restricted stock vesting starting April 24, 2026

Restricted stock vesting 33 1/3% annually 33 1/3% per year Restricted stock vesting starting February 25, 2027

Key Terms

tax-withholding disposition, restricted stock, vest at a rate of 20% per year, vest at a rate of 33 1/3% per year, +1 more

5 terms

tax-withholding disposition financial

"3,589 shares were used to satisfy tax obligations at a price of $19.82 per share"

A tax-withholding disposition is an event or transaction—such as selling or transferring securities, exercising options, or receiving compensation—that triggers a requirement to hold back part of the payment and remit it to tax authorities. It matters to investors because it reduces the cash they receive immediately and can change the timing and amount of taxable income, like a cashier taking a portion of your sale proceeds to pay taxes before you get the rest.

restricted stock financial

"Includes shares of restricted stock which vest at a rate of 20% per year"

Shares granted to an individual that carry limits on transfer or sale until certain conditions are met, such as staying with the company for a set time or hitting performance targets. Think of them as a locked gift that gradually opens; for investors they matter because they affect how many shares may enter the market later, signal management incentives and potential dilution, and reveal confidence in future company performance.

vest at a rate of 20% per year financial

"restricted stock which vest at a rate of 20% per year commencing on April 24, 2026"

vest at a rate of 33 1/3% per year financial

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

Form 4 regulatory

"The Form 4 shows a tax-withholding disposition coded “F”"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

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^*

Roberts Christine

(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)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	SEVP and COO

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/24/2026

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)

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	04/24/2026		F		3,589	D	$19.82	71,081(1)(2)	D

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	04/27/2026
	** 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 Christine Roberts?

NB Bancorp reported that SEVP and COO Christine Roberts had 3,589 shares of Common Stock withheld on April 24, 2026, to cover tax obligations. This was a tax-withholding disposition, not an open-market sale or purchase of shares.

How many NB Bancorp (NBBK) shares does Christine Roberts hold after this Form 4?

Following the April 24, 2026 tax-withholding disposition, Christine Roberts directly holds 71,081 shares of NB Bancorp Common Stock. This total includes restricted stock awards that are scheduled to vest over time under the company’s long-term compensation arrangements.

Was the NB Bancorp (NBBK) Form 4 a market sale of shares?

No. The Form 4 shows a tax-withholding disposition coded “F,” where 3,589 shares were delivered at $19.82 per share to satisfy tax liabilities. This is an administrative transaction, not an open-market sale initiated for investment reasons.

At what price were NB Bancorp (NBBK) shares used for the tax withholding?

The 3,589 shares of NB Bancorp Common Stock used to satisfy tax obligations were valued at $19.82 per share. This valuation determines how many shares were needed to cover the applicable tax liability for the equity compensation event.

What are the vesting terms of Christine Roberts’ restricted NB Bancorp (NBBK) shares?

Her holdings include restricted stock vesting 20% per year starting April 24, 2026, and additional restricted stock vesting 33 1/3% per year starting February 25, 2027. These time-based vesting schedules link ongoing share ownership to continued service with NB Bancorp.