SUMMIT PARTNERS L P - 11 Aug 2026 Form 4 Insider Report for Klaviyo, Inc. (KVYO)

Reporting relationship: 10%+ Owner
Issuer ticker: KVYO
Reported as of: 11 Aug 2026
Net transaction value: -$88,550,000
SEC form: 4
Accepted by SEC: 13 Aug 2026, 16:30:07 UTC
Prior SEC filing: 05 Jan 2026
Source filing: View source filing
Reporting owner signature: /s/ Adam Hennessey, as attorney-in-fact for Summit Partners, L.P.

Key filing fact

SUMMIT PARTNERS L P filed Form 4 for Klaviyo, Inc. (KVYO) on 13 Aug 2026.

Key facts

This page summarizes SUMMIT PARTNERS L P's Form 4 filing for Klaviyo, Inc. (KVYO).
3 reported transactions and 6 derivative rows are listed below.
Accepted by SEC: 13 Aug 2026, 16:30.

Change

Previous filing in this sequence was filed on 05 Jan 2026.
Current net transaction value: -$88,550,000.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (6)

CIK 0000830588 Primary reporting owner

SUMMIT PARTNERS L P

Relationship: 10%+ Owner
Address: 222 BERKELEY STREET, 18TH FLOOR, BOSTON
Signature: /s/ Adam Hennessey, as attorney-in-fact for Summit Partners, L.P.
Signature date: 13 Aug 2026

CIK 0001634415

Summit Partners Growth Equity Fund IX-A, L.P.

Relationship: 10%+ Owner
Address: 222 BERKELEY STREET, 18TH FLOOR, BOSTON
Signature: /s/ Adam Hennessey, as attorney-in-fact for Summit Investors GE IX/VC IV, LLC
Signature date: 13 Aug 2026

CIK 0001634426

Summit Partners Growth Equity Fund IX-B, L.P.

Relationship: 10%+ Owner
Address: 222 BERKELEY STREET, 18TH FLOOR, BOSTON
Signature: /s/ Adam Hennessey, as attorney-in-fact for Summit Partners Co-Invest (Kiwi), L.P.
Signature date: 13 Aug 2026

CIK 0001830877

Summit Partners Co-Invest (Kiwi), LP

Relationship: 10%+ Owner
Address: 222 BERKELEY STREET, 18TH FLOOR, BOSTON
Signature: /s/ Adam Hennessey, as attorney-in-fact for Summit Partners Growth Equity Fund IX-A, L.P.
Signature date: 13 Aug 2026

CIK 0001654074

SUMMIT INVESTORS GE IX/VC IV, LLC

Relationship: 10%+ Owner
Address: 222 BERKELEY STREET, 18TH FLOOR, BOSTON
Signature: /s/ Adam Hennessey, as attorney-in-fact for Summit Investors GE IX/VC IV (UK), L.P.
Signature date: 13 Aug 2026

CIK 0001846709

SUMMIT INVESTORS GE IX/VC IV (UK), L.P.

Relationship: 10%+ Owner
Address: 222 BERKELEY STREET, 18TH FLOOR, BOSTON
Signature: /s/ Adam Hennessey, as attorney-in-fact for Summit Partners Growth Equity Fund IX-B, L.P.
Signature date: 13 Aug 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

KVYO transaction

Series A Common Stock, par value $0.001 per share

Conversion of derivative security

Transaction value
Shares: +5,000,000
Change %
Price
Shares after: 5,000,000
Date: 11 Aug 2026
Ownership: See footnotes
Footnotes: F1, F2, F3, F4

KVYO transaction

Series A Common Stock, par value $0.001 per share

Conversion of derivative security

Transaction value
Shares: +5,000,000
Change %
Price
Shares after: 5,000,000
Date: 11 Aug 2026
Ownership: See footnotes
Footnotes: F1, F2, F3, F4

KVYO transaction

Series A Common Stock, par value $0.001 per share

Conversion of derivative security

Transaction value
Shares: +5,000,000
Change %
Price
Shares after: 5,000,000
Date: 11 Aug 2026
Ownership: See footnotes
Footnotes: F1, F2, F3, F4

KVYO transaction

Series A Common Stock, par value $0.001 per share

Conversion of derivative security

Transaction value
Shares: +5,000,000
Change %
Price
Shares after: 5,000,000
Date: 11 Aug 2026
Ownership: See footnotes
Footnotes: F1, F2, F3, F4

KVYO transaction

Series A Common Stock, par value $0.001 per share

Conversion of derivative security

Transaction value
Shares: +5,000,000
Change %
Price
Shares after: 5,000,000
Date: 11 Aug 2026
Ownership: See footnotes
Footnotes: F1, F2, F3, F4

KVYO transaction

Series A Common Stock, par value $0.001 per share

Conversion of derivative security

Transaction value
Shares: +5,000,000
Change %
Price
Shares after: 5,000,000
Date: 11 Aug 2026
Ownership: See footnotes
Footnotes: F1, F2, F3, F4

KVYO transaction

Series A Common Stock, par value $0.001 per share

Sale

Transaction value: $88,550,000
Shares: -5,000,000
Change %: -100%
Price: $17.71
Shares after: 0
Date: 11 Aug 2026
Ownership: See footnotes
Footnotes: F2, F3, F4

KVYO transaction

Series A Common Stock, par value $0.001 per share

Sale

Transaction value: $88,550,000
Shares: -5,000,000
Change %: -100%
Price: $17.71
Shares after: 0
Date: 11 Aug 2026
Ownership: See footnotes
Footnotes: F2, F3, F4

KVYO transaction

Series A Common Stock, par value $0.001 per share

Sale

Transaction value: $88,550,000
Shares: -5,000,000
Change %: -100%
Price: $17.71
Shares after: 0
Date: 11 Aug 2026
Ownership: See footnotes
Footnotes: F2, F3, F4

KVYO transaction

Series A Common Stock, par value $0.001 per share

Sale

Transaction value: $88,550,000
Shares: -5,000,000
Change %: -100%
Price: $17.71
Shares after: 0
Date: 11 Aug 2026
Ownership: See footnotes
Footnotes: F2, F3, F4

KVYO transaction

Series A Common Stock, par value $0.001 per share

Sale

Transaction value: $88,550,000
Shares: -5,000,000
Change %: -100%
Price: $17.71
Shares after: 0
Date: 11 Aug 2026
Ownership: See footnotes
Footnotes: F2, F3, F4

KVYO transaction

Series A Common Stock, par value $0.001 per share

Sale

Transaction value: $88,550,000
Shares: -5,000,000
Change %: -100%
Price: $17.71
Shares after: 0
Date: 11 Aug 2026
Ownership: See footnotes
Footnotes: F2, F3, F4

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

KVYO transaction Derivative

Series B Common Stock, par value $0.001 per share

Conversion of derivative security

Transaction value
Shares: +5,000,000
Change %: +56%
Price
Shares after: 13,852,778
Date: 11 Aug 2026
Ownership: See footnotes
Underlying class: Series A Common Stock, par value $0.001 per share
Underlying amount: 5,000,000
Exercise price
Footnotes: F1, F2, F3, F4, F5

KVYO transaction Derivative

Series B Common Stock, par value $0.001 per share

Conversion of derivative security

Transaction value
Shares: +5,000,000
Change %: +56%
Price
Shares after: 13,852,778
Date: 11 Aug 2026
Ownership: See footnotes
Underlying class: Series A Common Stock, par value $0.001 per share
Underlying amount: 5,000,000
Exercise price
Footnotes: F1, F2, F3, F4, F5

KVYO transaction Derivative

Series B Common Stock, par value $0.001 per share

Conversion of derivative security

Transaction value
Shares: +5,000,000
Change %: +56%
Price
Shares after: 13,852,778
Date: 11 Aug 2026
Ownership: See footnotes
Underlying class: Series A Common Stock, par value $0.001 per share
Underlying amount: 5,000,000
Exercise price
Footnotes: F1, F2, F3, F4, F5

KVYO transaction Derivative

Series B Common Stock, par value $0.001 per share

Conversion of derivative security

Transaction value
Shares: +5,000,000
Change %: +56%
Price
Shares after: 13,852,778
Date: 11 Aug 2026
Ownership: See footnotes
Underlying class: Series A Common Stock, par value $0.001 per share
Underlying amount: 5,000,000
Exercise price
Footnotes: F1, F2, F3, F4, F5

KVYO transaction Derivative

Series B Common Stock, par value $0.001 per share

Conversion of derivative security

Transaction value
Shares: +5,000,000
Change %: +56%
Price
Shares after: 13,852,778
Date: 11 Aug 2026
Ownership: See footnotes
Underlying class: Series A Common Stock, par value $0.001 per share
Underlying amount: 5,000,000
Exercise price
Footnotes: F1, F2, F3, F4, F5

KVYO transaction Derivative

Series B Common Stock, par value $0.001 per share

Conversion of derivative security

Transaction value
Shares: +5,000,000
Change %: +56%
Price
Shares after: 13,852,778
Date: 11 Aug 2026
Ownership: See footnotes
Underlying class: Series A Common Stock, par value $0.001 per share
Underlying amount: 5,000,000
Exercise price
Footnotes: F1, F2, F3, F4, F5

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 5 footnotes

Footnote F1

The Series B common stock, par value $0.001 per share ("Series B Common Stock"), is convertible into an equal number of shares of Series A common stock, par value $0.001 per share ("Series A Common Stock"), at any time, at the holder's election, and has no expiration date. Each share of Series B Common Stock will automatically convert into Series A Common Stock upon the earlier of (i) the date specified by 66-2/3% of the outstanding shares of Series B Common Stock, voting as a single series; (ii) following the seventh anniversary of the closing of Klaviyo, Inc.'s (the "Company") initial public offering; or (iii) any transfer, whether or not for value, except for certain permitted transfers described in the Company's certificate of incorporation.

Footnote F2

Summit Partners, L.P. is the manager of Summit Partners GE IX, LLC, which is the general partner of Summit Partners GE IX, LP, which is the general partner of Summit Partners Growth Equity Fund IX-A, L.P. ("Fund IX-A") and Summit Partners Growth Equity Fund IX-B, L.P. ("Fund IX-B"). Summit Partners, L.P. is the managing member of Summit Partners Co-Invest Kiwi GP, LLC, which is the general partner of Summit Partners Co-Invest (Kiwi), L.P. ("Kiwi Co-Invest Fund"). Summit Master Company, LLC is the general partner of Summit Partners, L.P., which is the manager of Summit Investors Management, LLC, which is the manager of Summit Investors GE IX/VC IV, LLC ("Fund IX/VC IV") and the general partner of Summit Investors GE IX/VC IV (UK), L.P. ("Fund IX/VC IV (UK)").

Footnote F3

(continued from footnote 2) Summit Master Company, LLC, as the managing member of Summit Investors Management, LLC, has delegated voting and investment decisions with respect to the securities held by Fund IX/VC IV and Fund IX/VC IV (UK) to Summit Partners, L.P.

Footnote F4

The investment committee of Summit Partners, L.P., is currently composed of Peter Y. Chung, Scott C. Collins, and Peter L. Rottier, who may be deemed to have voting and dispositive authority over, and therefore beneficial ownership of, the reported securities. Each of the foregoing entities, Mr. Chung, Mr. Collins, and Mr. Rottier disclaims beneficial ownership of the shares, except to the extent of such person's or entity's pecuniary interest therein and the filing of this statement shall not be deemed an admission that any of the foregoing entities or persons are, for purposes of Section 16 of the Act or otherwise, the beneficial owner of any equity securities covered by this statement.

Footnote F5

Consists of (i) 8,187,302 shares of Series B Common Stock held by Fund IX-A, (ii) 5,112,037 shares of Series B Common Stock held by Fund IX-B, (iii) 504,825 shares of Series B Common Stock held by Kiwi Co-Invest Fund, (iv) 43,030 shares of Series B Common Stock held by Fund IX/VC IV, and (v) 5,584 shares of Series B Common Stock held by Fund IX/VC IV (UK).