Klaviyo (KVYO) founder Andrew Bialecki reports 75.3M-share, 36.5% stake

Rhea-AI Filing Summary

Klaviyo, Inc. (KVYO) discloses that founder Andrew Bialecki is a major beneficial owner of its Series A common stock. As of June 30, 2026, he may be deemed to beneficially own 75,326,229 shares of Series A common stock, representing 36.5% of that class.

This beneficial ownership is calculated based on 131,203,855 shares of Series A common stock outstanding plus 75,326,229 shares issuable upon conversion of Series B common stock held by Bialecki and related parties. The position includes shares held directly, by his spouse, and through several grantor retained annuity trusts and irrevocable GST trusts, over which he or his spouse serves as trustee. He reports sole voting and dispositive power over 75,326,229 shares and no shared voting or dispositive power.

Key Figures

Beneficial ownership: 75,326,229 shares of Series A common stock Ownership percentage: 36.5% Shares outstanding: 131,203,855 shares +4 more

7 metrics

Beneficial ownership 75,326,229 shares of Series A common stock Deemed beneficially owned by Andrew Bialecki as of June 30, 2026

Ownership percentage 36.5% Percentage of Klaviyo Series A common stock beneficially owned by Andrew Bialecki

Shares outstanding 131,203,855 shares Series A common stock outstanding as of June 30, 2026

Conversion shares 75,326,229 shares Series A shares issuable upon conversion of Series B common stock held by or for Bialecki

Direct Series B-based holdings 64,731,589 shares Series A shares underlying Series B common stock held directly by Andrew Bialecki

Trust I of 2023 holdings 7,517,410 shares Series A shares underlying Series B common stock in the 2023 Grantor Retained Annuity Trust

Trust I of 2026 holdings 2,000,000 shares Series A shares underlying Series B common stock in the 2026 Grantor Retained Annuity Trust

Key Terms

beneficial owner, Series B common stock, Grantor Retained Annuity Trust, Irrevocable GST Trust, +1 more

5 terms

beneficial owner regulatory

"The Reporting Person may be deemed to be the beneficial owner of 75,326,229 shares"

A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.

Series B common stock financial

"shares of Series A Common Stock issuable upon conversion of shares of the Issuer's Series B common stock"

Grantor Retained Annuity Trust financial

"Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023, of which the Reporting Person serves as trustee"

A grantor retained annuity trust (GRAT) is an estate-planning tool where the person who creates the trust transfers assets into it but receives fixed cash payments (an annuity) from the trust for a set number of years; whatever remains after that term passes to designated beneficiaries. It matters to investors because it can shift future appreciation of assets out of the creator’s taxable estate—like putting an asset into a timed vending machine that pays you fixed amounts while any extra value that grows inside the machine goes to heirs with reduced gift or estate tax consequences.

Irrevocable GST Trust financial

"Andrew P. Bialecki Irrevocable GST Trust of 2023, of which the Reporting Person's spouse serves as a trustee"

sole voting power regulatory

"Sole power to vote or to direct the vote: 75,326,229"

Sole voting power is the exclusive right to cast votes attached to a shareholder’s stock without needing approval from anyone else. Like holding the only remote control for a TV, it lets that holder decide corporate matters such as board members, mergers, and policy changes, making it important to investors because it concentrates control and can strongly influence a company’s strategy and the value of its shares.

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

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Available on EDGAR 08/05/2026 - 06:46 PM Accepted by SEC EDGAR 08/05/2026 - 06:45 PM Learn about SEC filing dates

FAQ

How many Klaviyo (KVYO) shares does Andrew Bialecki beneficially own?

Andrew Bialecki may be deemed to beneficially own 75,326,229 shares of Klaviyo Series A common stock. This total includes shares underlying Series B common stock held directly, by his spouse, and through multiple trusts.

What percentage of Klaviyo (KVYO) Series A common stock does Andrew Bialecki hold?

Andrew Bialecki reports beneficial ownership of 36.5% of Klaviyo’s Series A common stock. This percentage is calculated using outstanding Series A shares plus shares issuable upon conversion of his Series B holdings.

How is Andrew Bialecki’s ownership in Klaviyo (KVYO) structured?

His 75,326,229 shares of deemed beneficial ownership include direct holdings, shares held by his spouse, and shares held through several grantor retained annuity and irrevocable GST trusts for which he or his spouse acts as trustee.

What voting power does Andrew Bialecki have over Klaviyo (KVYO) shares?

Andrew Bialecki reports sole voting power over 75,326,229 shares of Klaviyo Series A common stock and no shared voting power. He also reports sole dispositive power over the same number of shares.

What share count did Klaviyo (KVYO) report as outstanding for calculating Andrew Bialecki’s stake?

Klaviyo reported 131,203,855 shares of Series A common stock outstanding as of June 30, 2026. This figure is used, plus conversion shares from Series B stock, to compute Bialecki’s 36.5% ownership.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 4)

Klaviyo, Inc. (the "Issuer")

(Name of Issuer)

Series A common stock, par value $0.001 per share (the "Series A Common Stock")

(Title of Class of Securities)

49845K101

(CUSIP Number)

06/30/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 49845K101

1

Names of Reporting Persons

Bialecki Andrew

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 75,326,229.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 75,326,229.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

75,326,229.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

36.5 %

12

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Klaviyo, Inc. (the "Issuer")
(b)	Address of issuer's principal executive offices: 125 Summer Street, 6th Floor, Boston, Massachusetts, 02110
Item 2.
(a)	Name of person filing: This statement is filed on behalf of Andrew Bialecki (the "Reporting Person").
(b)	Address or principal business office or, if none, residence: The business address of the Reporting Person is c/o Klaviyo, Inc., 125 Summer Street, 6th Floor, Boston, MA 02110.
(c)	Citizenship: The Reporting Person is a citizen of the United States of America.
(d)	Title of class of securities: Series A common stock, par value $0.001 per share (the "Series A Common Stock")
(e)	CUSIP No.: 49845K101
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: The ownership information below represents beneficial ownership of Series A Common Stock of the Issuer as of June 30, 2026, based on (i) 131,203,855 shares of Series A Common Stock outstanding as of June 30, 2026, as reported by the Issuer to the Reporting Person, plus (ii) an aggregate of 75,326,229 shares of Series A Common Stock issuable upon conversion of shares of the Issuer's Series B common stock, par value $0.001 per share (the "Series B Common Stock"), beneficially owned by the Reporting Person, which are deemed outstanding pursuant to SEC Rule 13-3(d)(1)(i) only for purposes of computing the percentage ownership of the Reporting Person. The Reporting Person may be deemed to be the beneficial owner of 75,326,229 shares of Series A Common Stock, which includes: (i) 64,731,589 shares of Series A Common Stock underlying shares of Series B Common Stock held directly by the Reporting Person, (ii) 43,218 shares of Series A Common Stock underlying shares of Series B Common Stock held by the Reporting Person's spouse, (iii) 7,517,410 shares of Series A Common Stock underlying shares of Series B Common Stock held by the Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023, of which the Reporting Person serves as trustee, (iv) 2,000,000 shares of Series A Common Stock underlying shares of Series B Common Stock held by the Andrew P. Bialecki Grantor Retained Annuity Trust I of 2026, of which the Reporting Person serves as a trustee, (v) 517,006 shares of Series A Common Stock underlying shares of Series B Common Stock held by the Andrew P. Bialecki Irrevocable GST Trust of 2023, of which the Reporting Person's spouse serves as a trustee, and (vi) 517,006 shares of Series A Common Stock underlying shares of Series B Common Stock held by the Elizabeth L. Bialecki Irrevocable GST Trust of 2023, of which the Reporting Person serves as a trustee.
(b)	Percent of class: 36.5%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 75,326,229
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 75,326,229
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.	Certifications:
	Not Applicable

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Bialecki Andrew

Signature:	/s/ Andrew Bialecki
Name/Title:	Andrew Bialecki
Date:	08/05/2026