| Item 1. | |
| (a) | Name of issuer:
Klaviyo, Inc. (the "Issuer") |
| (b) | Address of issuer's principal executive offices:
125 Summer Street, 6th Floor, Boston, MA, 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, 2025, based on (i) 116,877,930 shares of Series A Common Stock outstanding as of June 30, 2025, as reported by the Issuer to the Reporting Person, plus (ii) an aggregate of 87,796,336 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 87,796,336 shares of Series A Common Stock, which includes: (i) 74,773,276 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) 11,945,830 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) 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 (v) 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:
42.9% |
| (c) | Number of shares as to which the person has:
|
| | (i) Sole power to vote or to direct the vote:
87,796,336
|
| | (ii) Shared power to vote or to direct the vote:
0
|
| | (iii) Sole power to dispose or to direct the disposition of:
87,796,336
|
| | (iv) Shared power to dispose or to direct the disposition of:
0
|
| Item 5. | Ownership of 5 Percent or Less of a Class. |
| | |
| 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
|
Rule 13d-1(d)