Klaviyo (NYSE: KVYO) co-CEO Bialecki sells 206,827 shares in 10b5-1 plan

Rhea-AI Filing Summary

Klaviyo, Inc. co-CEO Andrew Bialecki converted 206,827 shares of Series B Common Stock into Series A Common Stock and then sold 206,827 Series A shares in open-market transactions around $19.96 and $19.34 per share under a pre-arranged Rule 10b5-1 trading plan. After these trades, he reports 68,344,118 Series B shares held directly and maintains additional indirect interests in shares held by several 2023 trusts and by his spouse, for which he disclaims beneficial ownership except for any pecuniary interest.

Insights

Equity analyst

Planned sales by Klaviyo's co-CEO are small relative to his disclosed stake.

Co-CEO Andrew Bialecki converted 206,827 Series B shares into Series A and sold the same number of Series A shares at weighted average prices near $19.96 and $19.34. The transactions are explicitly described as occurring under a Rule 10b5-1 trading plan adopted on May 20, 2025, indicating they were pre-scheduled rather than opportunistic.

Following the sales, he still holds 68,344,118 Series B shares directly and has indirect interests in additional shares through 2023 trusts and his spouse, where beneficial ownership is disclaimed except for any pecuniary interest. Given the remaining holdings and the pre-planned nature of the trades, this filing looks like routine liquidity management rather than a change in long-term outlook.

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

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)
03/10/2026

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	03/10/2026		C(1)		206,827	A	(2)	206,827	D
Series A Common Stock	03/10/2026		S(1)		206,127	D	$19.96(3)	700	D
Series A Common Stock	03/10/2026		S(1)		700	D	$19.34(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)	03/10/2026		C(1)			206,827	(2)	(2)	Series A Common Stock	206,827	$0	68,344,118	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 $19.375 to $20.37 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 $19.28 to $19.37 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	03/12/2026
	** 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 did Klaviyo (KVYO) co-CEO Andrew Bialecki report in this Form 4?

Andrew Bialecki reported converting 206,827 Series B Common shares into Series A and selling 206,827 Series A shares in open-market trades. The weighted average sale prices were around $19.96 and $19.34 per share, all under a pre-arranged Rule 10b5-1 trading plan.

At what prices did Andrew Bialecki sell Klaviyo (KVYO) Series A shares?

He sold 206,127 Series A shares at a weighted average price of $19.96 per share, with actual trades ranging from $19.375 to $20.37. He also sold 700 shares at a weighted average of $19.34, with trades between $19.28 and $19.37.

Was Andrew Bialecki’s Klaviyo (KVYO) share sale pre-planned under a Rule 10b5-1 plan?

Yes. The filing states the transactions were effected pursuant to a Rule 10b5-1 trading plan adopted on May 20, 2025. Such plans schedule trades in advance, so the timing typically reflects pre-set instructions rather than a new judgment about Klaviyo’s short-term prospects.

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

After the reported trades, he holds 68,344,118 shares of Series B Common Stock directly. He also has indirect interests in additional shares held through several 2023 trusts and by his spouse, while formally disclaiming beneficial ownership except to the extent of any pecuniary interest.

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

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

How significant is Andrew Bialecki’s Klaviyo (KVYO) stock sale compared with his remaining stake?

The reported sale covers 206,827 Series A shares, while he still directly holds 68,344,118 Series B shares plus indirect interests via trusts and his spouse. Based on those disclosed figures, the sale represents only a small portion of his overall economic exposure to Klaviyo.