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

1. Name and Address of Reporting Person* Chen Weidong (Last) (First) (Middle) C/O CASA SYSTEMS, INC. 100 OLD RIVER ROAD (Street) ANDOVER MA 01810 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol Casa Systems Inc [ CASA ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) See Remarks
	3. Date of Earliest Transaction (Month/Day/Year) 12/08/2023
	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
	Rule 10b5-1(c) Transaction Indication Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

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	12/08/2023		M		366,611	A	(1)	2,658,412	D
Common Stock	12/08/2023		F(2)		121,366	D	$0.54	2,537,046	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
Restricted Stock Units	(3)	12/08/2023		M			53,303	(4)	(4)	Common Stock	53,303	$0	0	D
Restricted Stock Units	(3)	12/08/2023		M			47,934	(5)	(5)	Common Stock	47,934	$0	0	D
Restricted Stock Units	(3)	12/08/2023		M			241,407	(6)	(6)	Common Stock	241,407	$0	0	D
Restricted Stock Units	(3)	12/08/2023		A		23,967		(7)	(7)	Common Stock	23,967	$0	23,967	D
Restricted Stock Units	(3)	12/08/2023		M			23,967	(8)	(8)	Common Stock	23,967	$0	0	D

Explanation of Responses:

1. Restricted stock units ("RSUs") converted into common stock, $0.001 par value per share (the "Common Stock"), of Casa Systems, Inc. (the "Company") on a one-for-one basis upon vesting of the RSU.

2. Shares withheld by the Company to satisfy tax withholding requirements on vesting of RSUs. No shares were sold.

3. Each RSU represents the right to receive one share of Common Stock of Company upon vesting, subject to the reporting person's continued service relationship with the Company and the other terms and conditions set forth in the applicable RSU Agreement. In the sole discretion of the Company's board of directors, the Company may, with respect to any applicable vesting date, deliver to the reporting person Common Stock or cash having a fair market value equal to the number of shares of Common Stock underlying the portion of the RSU that vested on such date, payable within 30 days of the vesting date, less applicable taxes.

4. Pursuant to the Separation Agreement entered into by the Company and the reporting person on November 17, 2023 (the "Separation Agreement"), the vesting of the RSUs granted to the reporting person on February 25, 2020, was fully accelerated and all of the shares underlying the award became vested as of December 8, 2023. The RSUs have no expiration date.

5. Pursuant to the Separation Agreement, the vesting of the RSUs granted to the reporting person on February 23, 2021, was fully accelerated and all of the shares underlying the award became vested as of December 8, 2023. The RSUs have no expiration date.

6. Pursuant to the Separation Agreement, the vesting of the RSUs granted to the reporting person on May 9, 2022, was fully accelerated and all of the shares underlying the award became vested as of December 8, 2023. The RSUs have no expiration date.

7. These RSUs were granted to the reporting person on February 23, 2021, subject to performance-based vesting conditions. The vesting of these RSUs was fully accelerated as of December 8, 2023, pursuant to the Separation Agreement. These RSUs have no expiration date.

8. Pursuant to the Separation Agreement, the vesting of the RSUs granted to the reporting person on February 23, 2021, was fully accelerated and all of the shares underlying the award became vested as of December 8, 2023. The RSUs have no expiration date.

Remarks:

Former Chief Technology Officer

	/s/ Timothy C. Rodenberger, as Attorney-in-Fact	12/12/2023
	** Signature of Reporting Person	Date
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