Klaviyo (NYSE: KVYO) CEO sells Series A shares under Rule 10b5-1 plan

Rhea-AI Filing Summary

Klaviyo Co-CEO Andrew Bialecki reported a planned stock sale under a Rule 10b5-1 trading plan. On January 27, 2026, he converted 155,219 shares of Series B Common Stock into 155,219 shares of Series A Common Stock at a conversion price of $0.

He then sold 150,689 Series A shares at a weighted average price of $25.34 and 4,530 Series A shares at a weighted average price of $24.94, leaving no Series A shares held directly afterward. He continues to hold 68,950,945 Series B shares directly, while additional Series B shares are held indirectly through several 2023 trusts and by his spouse, for which he disclaims beneficial ownership except to the extent of any pecuniary interest.

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

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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)
01/27/2026

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	01/27/2026		C(1)		155,219	A	(2)	155,219	D
Series A Common Stock	01/27/2026		S(1)		150,689	D	$25.34(3)	4,530	D
Series A Common Stock	01/27/2026		S(1)		4,530	D	$24.94(4)	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)	01/27/2026		C(1)			155,219	(2)	(2)	Series A Common Stock	155,219	$0	68,950,945	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(5)
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(6)
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(7)
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 $25.01 to $26.00 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 $24.82 to $25.00 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. 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.

6. 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.

7. 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	01/29/2026
	** 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).
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FAQ

What insider transaction did Andrew Bialecki report for Klaviyo (KVYO)?

Andrew Bialecki reported converting 155,219 Klaviyo Series B shares into Series A, then selling all 155,219 Series A shares in two transactions on January 27, 2026, under a pre-established Rule 10b5-1 trading plan adopted on May 20, 2025.

How many Klaviyo Series A shares were sold in this Form 4 filing for KVYO?

The filing shows sales of 150,689 Klaviyo Series A shares at a weighted average price of $25.34 and 4,530 Series A shares at a weighted average price of $24.94, with Andrew Bialecki holding no Series A shares directly after these transactions.

At what prices did the Klaviyo (KVYO) CEO sell Series A stock on January 27, 2026?

Andrew Bialecki sold Klaviyo Series A shares at weighted average prices of $25.34 and $24.94. Footnotes explain these averages reflect multiple trades in ranges of $25.01–$26.00 and $24.82–$25.00 per share, with detailed breakdowns available upon request.

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

Each share of Klaviyo Series B Common Stock is convertible at any time into one share of Series A Common Stock. Series B automatically converts into Series A upon certain events described in the company’s certificate of incorporation, and Series B has no expiration date.

How many Klaviyo Series B shares does Andrew Bialecki hold directly after this Form 4?

After the reported transactions, Andrew Bialecki directly holds 68,950,945 shares of Klaviyo Series B Common Stock. These shares are separate from additional Series B holdings reported as indirect, which are held through several 2023 trusts and by his spouse.

What Klaviyo (KVYO) shares are held through trusts associated with Andrew Bialecki?

Indirect holdings include 7,517,410 Series B shares through the Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023 and 517,006 Series B shares in each of two 2023 irrevocable GST trusts. He disclaims Section 16 beneficial ownership except for any pecuniary interest.

Was the Klaviyo CEO’s stock sale part of a Rule 10b5-1 plan?

Yes. The filing states the transactions were executed under a Rule 10b5-1 trading plan adopted by Andrew Bialecki on May 20, 2025. Such plans pre-schedule trades, allowing executives to sell shares over time according to predefined instructions.