Klaviyo co-CEO sells 200K shares under 10b5-1

Klaviyo, Inc. co-CEO Andrew Bialecki executed a planned option conversion and share sale.

Rhea-AI Filing Summary

Klaviyo, Inc. co-CEO Andrew Bialecki executed a planned option conversion and share sale. He converted 200,000 shares of Series B Common Stock into 200,000 shares of Series A Common Stock at a conversion price of $0.0000 per share, then sold all 200,000 Series A shares at a weighted average price of $18.17 per share in open-market transactions.

These trades were made under a Rule 10b5-1 trading plan adopted on May 20, 2025. Following the transactions, he holds 67,944,118 shares of Series B Common Stock directly and additional indirect interests through 2023 trusts and shares held by his spouse, each tied to Series B that is convertible 1-for-1 into Series A with no expiration.

Insider Trade Summary 10b5-1

Exercise and Sale: 200,000 shares ($3.63M approx. pre-tax spread)

Exercise and Sale 7 txns

Insider Bialecki Andrew

Role Co-Chief Executive Officer

Sold 200,000 shs ($3.63M)

Approx. gross sale proceeds $3.63M

Approx. exercise cost $0.00

Approx. pre-tax spread $3.63M

Type	Security	Shares	Price	Value
Conversion	Series B Common Stock	200,000	$0.00	$0.00
Conversion	Series A Common Stock	200,000	$0.00	$0.00
Sale	Series A Common Stock	200,000	$18.17	$3.63M
holding	Series B Common Stock	--	--	--
holding	Series B Common Stock	--	--	--
holding	Series B Common Stock	--	--	--
holding	Series B Common Stock	--	--	--

Holdings After Transaction: Series B Common Stock — 67,944,118 contracts (Direct); Series A Common Stock — 0 shares (Direct); Series B Common Stock — 7,517,410 contracts (Indirect, By The Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023); Series B Common Stock — 517,006 contracts (Indirect, By The Elizabeth L. Bialecki Irrevocable GST Trust of 2023); Series B Common Stock — 517,006 contracts (Indirect, By The Andrew P. Bialecki Irrevocable GST Trust of 2023); Series B Common Stock — 43,218 contracts (Indirect, By spouse)

Footnotes (6)

1. F1. 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. F2. 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. F3. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $17.77 to $18.65 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. F4. 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.
5. F5. 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.
6. F6. 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.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did Klaviyo (KVYO) co-CEO Andrew Bialecki report?

Andrew Bialecki reported converting 200,000 shares of Series B Common Stock into 200,000 Series A shares, then selling all 200,000 Series A shares. The sale was executed in open-market transactions at a weighted average price of $18.17 per share.

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

He sold 200,000 shares of Klaviyo Series A Common Stock. The weighted average sale price was $18.17 per share, with individual trades executed between $17.77 and $18.65 per share, according to the price range disclosed in the filing’s transaction footnote.

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

Yes. The filing states the transactions were effected under a Rule 10b5-1 trading plan adopted on May 20, 2025. Such plans are pre-arranged programs that schedule trades in advance, helping separate routine portfolio management from discretionary, market-timed insider transactions.

What Klaviyo (KVYO) holdings does Andrew Bialecki retain after this Form 4?

After the reported transactions, he holds 67,944,118 shares of Series B Common Stock directly. He also has indirect interests through several 2023 trusts and shares held by his spouse, each referencing Series B stock that is convertible into Series A on a one-for-one basis.

How are Klaviyo (KVYO) Series A and Series B Common Stock related in this filing?

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

What indirect Klaviyo (KVYO) holdings are reported through trusts and spouse accounts?

Indirect interests include shares held by the Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023 and two 2023 irrevocable GST trusts, plus shares held by his spouse. The filing notes he disclaims beneficial ownership of these trust-held shares except to any pecuniary interest.

AI-generated analysis. How Rhea-AI works. Not financial advice.

Form 4 Insider Transactions: What Each Field Means →

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Accepted by SEC EDGAR 03/26/2026 - 08:01 PM Learn about SEC filing dates

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 MASSACHUSETTS 02110

(City) (State) (Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
03/24/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

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	03/24/2026		C(1)		200,000	A	(2)	200,000	D
Series A Common Stock	03/24/2026		S(1)		200,000	D	$18.17(3)	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)	03/24/2026		C(1)			200,000	(2)	(2)	Series A Common Stock	200,000	$0	67,944,118	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(4)
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(5)
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(6)
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 $17.77 to $18.65 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. 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.

5. 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.

6. 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	03/26/2026
	** 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.
* Form 4: SEC 1474 (03-26)