Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 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 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * Shopify Strategic Holdings 3 LLC 2. Issuer Name and Ticker or Trading Symbol Klaviyo, Inc. [KVYO] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 103 FOULK ROAD, SUITE 218-A, 3. Date of Earliest Transaction (Month/Day/Year) 07/28/2025 (Street) WILMINGTON, DE 19803 4. If Amendment, Date Original Filed (Month/Day/Year) 6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) 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

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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 Underlying Securities (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 of Derivative Security: 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

Warrants to Purchase Series B Common Stock (Right to Buy)

$0.01

07/28/2025

X

344,383

(1)

07/28/2032

Series B Common Stock

344,383

$ 0

2,755,057

D(2)

Series B Common Stock

(3)

07/28/2025

X

344,383

(3)

(3)

Series A Common Stock

344,383

$0.01

15,939,963

D(2)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Shopify Strategic Holdings 3 LLC 103 FOULK ROAD, SUITE 218-A WILMINGTON, DE 19803		X
SHOPIFY INC. 151 O'CONNOR STREET GROUND FLOOR OTTAWA, A6 K2P 2L8		X

Signatures

SHOPIFY STRATEGIC HOLDINGS 3 LLC, By: /s/ Jason Kilpela, Director		07/29/2025
**Signature of Reporting Person		Date
SHOPIFY INC, By: /s/ Michael L. Johnson, Corporate Secretary		07/29/2025
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(1)	25% of the shares subject to the warrants vested on July 28, 2022, and the remaining shares vest quarterly in equal amounts through July 28, 2027. Notwithstanding the foregoing, in connection with the Issuer's initial public offering ("IPO"), 25% of the total number of shares subject to the warrants vested immediately prior to the completion of the IPO.
(2)	Reflects securities held directly by Shopify Strategic Holdings 3 LLC, a wholly-owned subsidiary of Shopify Inc. ("Shopify"). Shopify is an indirect beneficial owner and disclaims beneficial ownership except to the extent of its pecuniary interest therein.
(3)	Each share of Series B Common Stock is convertible at any time at the option of the holder into one share of Series A Common Stock of the Issuer, and will automatically convert into Series A Common Stock upon the occurrence of certain events as set forth in the Issuer's certificate of incorporation. The Series B Common Stock has no expiration date.

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