[Form 4] Brookline Bancorp Inc Insider Trading Activity

Rhea-AI Filing Summary

Marissa S. Martin, General Counsel and director of Brookline Bancorp, Inc. (BRKL), reported multiple dispositions of common stock on 08/25/2025. The filing shows four separate sales totaling 7,003 shares at a price of $11.03 per share, reflecting proceeds from performance-based restricted shares that vested under the company’s 2021 Stock Option and Incentive Plan and the Agreement and Plan of Merger with Berkshire Hills Bancorp. After these transactions, Ms. Martin beneficially owns 33,673 shares directly and 821 shares indirectly through an ESOP.

Positive

• Clear disclosure of the origin of the shares: performance-based restricted stock vested under the merger agreement
• Timely filing of Form 4 showing insider transactions
• Substantial remaining ownership: 33,673 shares held directly and 821 indirectly via ESOP

Negative

• Insider sold 7,003 shares (2,168 + 723 + 2,467 + 1,645) at $11.03, which increases share supply from an insider
• No mention of a 10b5-1 plan or pre-arranged trading plan on the form, so sales appear discretionary

Insights

Corporate Governance Expert

TL;DR: Routine post-vesting insider sales disclosed and properly reported, consistent with merger-related vesting.

The Form 4 indicates that performance-based restricted shares vested pursuant to merger terms and were then sold. The filing is specific about the source of the shares and shows continuing meaningful ownership—33,673 shares direct and 821 indirect—so this appears to be an expected liquidity action rather than a change in alignment with shareholders. No indication of a Rule 10b5-1 plan or other trading arrangement is made in the form.

Securities/Equity Analyst

TL;DR: Insider sold 7,003 shares at $11.03 each after vesting; impact on float is small relative to total outstanding shares.

The transactions are labeled as sales at $11.03 and total 7,003 shares. Because the shares originated from performance-based grants that vested on merger terms, the sales appear event-driven liquidity rather than ad hoc disposals. The reporter retains material ownership post-sale, which mitigates governance concerns. Without outstanding information on total outstanding shares or market reaction, this filing alone is not material to valuation.

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^*

Martin Marissa S.

(Last) (First) (Middle)

131 CLARENDON STREET

(Street)

BOSTON MA 02116

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
BROOKLINE BANCORP INC [ BRKL ]

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

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	General Counsel

3. Date of Earliest Transaction (Month/Day/Year)
08/25/2025

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	08/25/2025		F		2,168(1)	D	$11.03	38,508	D
Common	08/25/2025		F		723	D	$11.03	37,785	D
Common	08/25/2025		F		2,467	D	$11.03	35,318	D
Common	08/25/2025		F		1,645	D	$11.03	33,673	D
Common								33,673	D
Common								821	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. Performance based restricted stock shares granted pursuant to the Brookline Bancorp, Inc. 2021 Stock Option and Incentive Plan. The shares vested pursuant to the terms of the Agreement and Plan of Merger by and among Berkshire Hills Bancorp, Inc., Commerce Acquisition Sub, Inc., and Brookline Bancorp, Inc.

Remarks:

	Marissa S. Martin	08/27/2025
	** 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 insider sold shares of Brookline Bancorp (BRKL)?

Marissa S. Martin, General Counsel and director, reported the sales.

How many BRKL shares were sold and at what price?

A total of 7,003 shares were sold on 08/25/2025 at $11.03 per share.

Why were the shares sold according to the Form 4?

The sold shares were performance-based restricted stock that vested under the Brookline Bancorp 2021 Stock Option and Incentive Plan and the Agreement and Plan of Merger.

How many BRKL shares does the reporting person own after the transactions?

After the reported transactions, Ms. Martin beneficially owns 33,673 shares directly and 821 shares indirectly via an ESOP.

Was the sale part of a 10b5-1 trading plan?

The Form 4 does not indicate that the transactions were made pursuant to a Rule 10b5-1 plan.