Klaviyo (KVYO) Co-CEO Bialecki converts 200,000 shares and sells 200,000 in plan trades

Rhea-AI Filing Summary

Klaviyo, Inc. director and Co-CEO Andrew Bialecki reported derivative conversions and share sales. On March 3, 2026, he converted 200,000 shares of Series B Common Stock into 200,000 shares of Series A Common Stock at a stated price of $0.0000 per share.

On the same date, he sold a total of 200,000 Series A Common shares in open-market transactions, including 154,022 shares at a weighted average price of $18.86 (with individual trades between $18.22 and $19.21) and 45,978 shares at a weighted average price of $17.90 (with trades between $17.52 and $18.21), pursuant to a Rule 10b5-1 trading plan adopted on May 20, 2025.

After these transactions, he directly held 68,550,945 Series B shares and no Series A shares. Additional Series B shares are reported as held indirectly by the Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023 (7,517,410 shares), the Elizabeth L. Bialecki Irrevocable GST Trust of 2023 (517,006 shares), the Andrew P. Bialecki Irrevocable GST Trust of 2023 (517,006 shares), and his spouse (43,218 shares), with the filing stating that he disclaims Section 16 beneficial ownership of the trust-held shares 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

OMB Number:			3235-0287
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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).

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)
03/03/2026

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	03/03/2026		C(1)		200,000	A	(2)	200,000	D
Series A Common Stock	03/03/2026		S(1)		154,022	D	$18.86(3)	45,978	D
Series A Common Stock	03/03/2026		S(1)		45,978	D	$17.9(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)	03/03/2026		C(1)			200,000	(2)	(2)	Series A Common Stock	200,000	$0	68,550,945	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 $18.22 to $19.21 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 $17.52 to $18.21 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	03/05/2026
	** 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 KVYO Co-CEO Andrew Bialecki report on March 3, 2026?

Andrew Bialecki reported converting 200,000 Series B Common shares into 200,000 Series A shares, then selling 200,000 Series A shares in open-market trades. These transactions were executed under a pre-established Rule 10b5-1 trading plan adopted on May 20, 2025.

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

He sold 200,000 Series A Common shares in total. This included 154,022 shares at a weighted average price of $18.86 and 45,978 shares at a weighted average price of $17.90, with individual trades occurring within stated price ranges in the filing.

How many Klaviyo (KVYO) shares does Andrew Bialecki hold directly after these Form 4 transactions?

Following the reported transactions, Andrew Bialecki directly held 68,550,945 shares of Klaviyo’s Series B Common Stock and no Series A Common shares. The filing also lists additional Series B holdings reported as held indirectly through various trusts and by his spouse.

Were Andrew Bialecki’s KVYO share sales made under a Rule 10b5-1 trading plan?

Yes. The filing states the reported transactions were effected under a Rule 10b5-1 trading plan adopted on May 20, 2025. Such plans allow insiders to pre-arrange trades, helping separate personal trading decisions from subsequent market-sensitive information.

What indirect Klaviyo (KVYO) holdings related to Andrew Bialecki are disclosed in the Form 4?

The Form 4 reports Series B Common Stock held indirectly by the Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023, two 2023 GST trusts, and his spouse. The filing states he disclaims Section 16 beneficial ownership of the trust-held shares except for any pecuniary interest.

What does the Form 4 say about conversion rights of Klaviyo’s Series B Common Stock?

It states each Series B Common Stock share is convertible at any time, at the holder’s option, into one Series A Common share and will automatically convert upon specified events described in the certificate of incorporation. The Series B Common Stock has no expiration date.