Klaviyo (KVYO) Co-CEO Bialecki Reports 10b5-1 Stock Sales

Rhea-AI Filing Summary

Klaviyo, Inc. insider activity: Co-Chief Executive Officer and director Andrew Bialecki reported preset stock sales executed under a Rule 10b5-1 trading plan adopted on May 20, 2025. On January 6, 2026, he converted 137,504 shares of Series B Common Stock into Series A Common Stock and sold 135,122 Series A shares at a weighted average price of $28.92 per share and 2,382 shares at a weighted average price of $28.52 per share. On January 7, 2026, he converted a further 16,649 Series B shares into Series A and sold all 16,649 Series A shares at a weighted average price of $30.01 per share. Each Series B share is convertible into one Series A share and has no expiration date. Following these transactions, he reports 69,414,736 Series B shares held directly, with additional Series B shares held indirectly through family trusts and by his spouse, subject to customary beneficial ownership disclaimers.

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
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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).

X

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^*

Bialecki Andrew

(Last) (First) (Middle)

C/O KLAVIYO, INC.

125 SUMMER STREET, 6TH FLOOR

(Street)

BOSTON MA 02110

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Klaviyo, Inc. [ KVYO ]

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

X	Director	X	10% Owner
X	Officer (give title below)		Other (specify below)
	Co-Chief Executive Officer

3. Date of Earliest Transaction (Month/Day/Year)
01/06/2026

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
Series A Common Stock	01/06/2026		C(1)		137,504	A	(2)	137,504	D
Series A Common Stock	01/06/2026		S(1)		135,122	D	$28.92(3)	2,382	D
Series A Common Stock	01/06/2026		S(1)		2,382	D	$28.52(4)	0	D
Series A Common Stock	01/07/2026		C(1)		16,649	A	(2)	16,649	D
Series A Common Stock	01/07/2026		S(1)		16,649	D	$30.01(5)	0	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
Series B Common Stock	(2)	01/06/2026		C(1)			137,504	(2)	(2)	Series A Common Stock	137,504	$0	69,431,385	D
Series B Common Stock	(2)	01/07/2026		C(1)			16,649	(2)	(2)	Series A Common Stock	16,649	$0	69,414,736	D
Series B Common Stock	(2)							(2)	(2)	Series A Common Stock	7,517,410		7,517,410	I	By The Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023(6)
Series B Common Stock	(2)							(2)	(2)	Series A Common Stock	517,006		517,006	I	By The Elizabeth L. Bialecki Irrevocable GST Trust of 2023(7)
Series B Common Stock	(2)							(2)	(2)	Series A Common Stock	517,006		517,006	I	By The Andrew P. Bialecki Irrevocable GST Trust of 2023(8)
Series B Common Stock	(2)							(2)	(2)	Series A Common Stock	43,218		43,218	I	By spouse

Explanation of Responses:

1. These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 20, 2025.

2. Each share of the Issuer's Series B Common Stock, par value $0.001 per share ("Series B Common Stock"), is convertible at any time at the option of the holder into one share of the Issuer's Series A Common Stock, par value $0.001 per share ("Series A Common Stock"), and will automatically convert into one share of 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.

3. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $28.545 to $29.54 per share. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

4. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $28.42 to $28.54 per share. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

5. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $30.00 to $30.06 per share. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

6. Shares held by the Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023, of which the Reporting Person serves as trustee. The Reporting Person disclaims Section 16 beneficial ownership of such shares except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed to be an admission that he has beneficial ownership of such shares for Section 16 or any other purpose.

7. Shares held by the Elizabeth L. Bialecki Irrevocable GST Trust of 2023, of which the Reporting Person serves as a trustee. The Reporting Person disclaims Section 16 beneficial ownership of such shares except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed to be an admission that he has beneficial ownership of such shares for Section 16 or any other purpose.

8. Shares held by the Andrew P. Bialecki Irrevocable GST Trust of 2023, of which the Reporting Person's spouse serves as a trustee. The Reporting Person disclaims Section 16 beneficial ownership of such shares except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed to be an admission that he has beneficial ownership of such shares for Section 16 or any other purpose.

Remarks:

	/s/ Landon Edmond, Attorney-in-Fact	01/08/2026
	** 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.

FAQ

What insider transactions did Klaviyo (KVYO) Co-CEO Andrew Bialecki report?

Andrew Bialecki reported converting Series B Common Stock into Series A Common Stock and selling the resulting Series A shares on January 6 and 7, 2026, as disclosed in the Form 4.

How many Klaviyo (KVYO) shares did Andrew Bialecki sell and at what prices?

On January 6, 2026, he sold 135,122 Series A shares at a weighted average price of $28.92 and 2,382 shares at a weighted average price of $28.52. On January 7, 2026, he sold 16,649 Series A shares at a weighted average price of $30.01.

Were Andrew Bialecki’s Klaviyo (KVYO) stock sales under a Rule 10b5-1 plan?

Yes. The filing states the transactions were effected pursuant to a Rule 10b5-1 trading plan adopted by Andrew Bialecki on May 20, 2025.

What is the relationship between Klaviyo’s Series A and Series B Common Stock?

Each share of Series B Common Stock is convertible at any time into one share of Series A Common Stock and will automatically convert into one Series A share upon certain events. The Series B stock has no expiration date.

How many Klaviyo (KVYO) shares does Andrew Bialecki report holding after these transactions?

After the reported transactions, he reports 69,414,736 shares of Series B Common Stock held directly, plus additional Series B shares held indirectly through specified 2023 trusts and by his spouse, with beneficial ownership disclaimed except to the extent of any pecuniary interest.

What trusts are associated with Andrew Bialecki’s indirect Klaviyo (KVYO) holdings?

Indirect holdings are reported through The Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023, The Elizabeth L. Bialecki Irrevocable GST Trust of 2023, The Andrew P. Bialecki Irrevocable GST Trust of 2023, and shares held by his spouse, with standard Section 16 beneficial ownership disclaimers.