# EDGAR Filing Document

**Accession Number:** 0001991099
**File Stem:** 0001470831-25-000292
**Filing Date:** 2025-11
**Character Count:** 8534
**Document Hash:** 915f53063b224d8d92a5ebb77e07f5c0
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001470831-25-000292.hdr.sgml**: 20251105

**ACCESSION NUMBER**: 0001470831-25-000292

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13G/A

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20251105

**DATE AS OF CHANGE**: 20251105

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Klaviyo, Inc.
- **CENTRAL INDEX KEY:** 0001835830
- **STANDARD INDUSTRIAL CLASSIFICATION:** SERVICES-PREPACKAGED SOFTWARE [7372]
- **ORGANIZATION NAME:** 06 Technology
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13G/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-94164
- **FILM NUMBER:** 251454289

**BUSINESS ADDRESS:**
- **STREET 1:** 125 SUMMER STREET, FLOOR 6
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02110
- **BUSINESS PHONE:** 800-338-1744

**MAIL ADDRESS:**
- **STREET 1:** 125 SUMMER STREET, FLOOR 6
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02110
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Bialecki Andrew
- **CENTRAL INDEX KEY:** 0001991099

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13G/A

**MAIL ADDRESS:**
- **STREET 1:** KLAVIYO, INC.
- **STREET 2:** 125 SUMMER STREET, 6TH FLOOR
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02110

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## SCHEDULE 13G

### Under the Securities Exchange Act of 1934

**(Amendment No. 2)**

**Issuer:** Klaviyo, Inc. (the "Issuer")

**Title of Class of Securities:** Series A common stock, par value $0.001 per share (the "Series A Common Stock")

**CUSIP Number:** 49845K101

**Date of Event Which Requires Filing of this Statement:** 09/30/2025

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

- [ ] Rule 13d-1(b)

- [ ] Rule 13d-1(c)

- [x] Rule 13d-1(d)

---

| 1. | Names of Reporting Persons<br>Bialecki Andrew | Names of Reporting Persons<br>Bialecki Andrew |
|:---|:---|:---|:---|
| 2. | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [ ] | Check the Appropriate Box if a Member of a Group (See Instructions)<br>(a) [ ] (b) [ ] |
| 3. | SEC Use Only | SEC Use Only |
| 4. | Citizenship or Place of Organization<br>X1 | Citizenship or Place of Organization<br>X1 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 5. | Sole Voting Power<br>83050885.00 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 6. | Shared Voting Power<br>0.00 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 7. | Sole Dispositive Power<br>83050885.00 |
| Number of<br>Shares<br>Beneficially<br>Owned by<br>Each<br>Reporting<br>Person<br>With | 8. | Shared Dispositive Power<br>0.00 |
| 9. | Aggregate Amount Beneficially Owned by Each Reporting Person<br>83050885.00 | Aggregate Amount Beneficially Owned by Each Reporting Person<br>83050885.00 |
| 10. | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] | Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) [ ] |
| 11. | Percent of Class Represented by Amount in Row (9)<br>37.7% | Percent of Class Represented by Amount in Row (9)<br>37.7% |
| 12. | Type of Reporting Person (See Instructions)<br>IN | Type of Reporting Person (See Instructions)<br>IN |

---

**Item 1(a). Name of Issuer:**
Klaviyo, Inc. (the "Issuer")

**Item 1(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").

**Item 2(b). Address of Principal Business Office:**
The business address of the Reporting Person is c/o Klaviyo, Inc., 125 Summer Street, 6th Floor, Boston, MA 02110.

**Item 2(c). Citizenship:**
The Reporting Person is a citizen of the United States of America.

**Item 2(d). Title of Class of Securities:**
Series A common stock, par value $0.001 per share (the "Series A Common Stock")

**Item 2(e). CUSIP Number:**
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 September 30, 2025, based on (i) 137,345,197 shares of Series A Common Stock outstanding as of September 30, 2025, as reported by the Issuer to the Reporting Person, plus (ii) an aggregate of 83,050,885 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 83,050,885 shares of Series A Common Stock, which includes: (i) 74,456,245 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) 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:**

37.7%

**(c) Number of shares as to which the person has:**

**(i) Sole power to vote or to direct the vote:**

83,050,885

**(ii) Shared power to vote or to direct the vote:**

0

**(iii) Sole power to dispose or to direct the disposition of:**

83,050,885

**(iv) Shared power to dispose or to direct the disposition of:**

0

**Item 5. Ownership of Five Percent or Less of a Class.**

[x] If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following.

**Item 6. Ownership of More than 5 Percent on Behalf of Another Person.**

Not Applicable

**Item 7. Identification and Classification of the Subsidiary**

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. Certification:**

—

### 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**

**Date:** 11/05/2025

**By:** /s/ Andrew Bialecki

**Name & Title:** Andrew Bialecki