STOCK TITAN

Klaviyo (KVYO) co-CEO logs 200K-share sale under 10b5-1 plan while retaining big stake

Filing Impact
(Neutral)
Filing Sentiment
(Neutral)
Form Type
4

Rhea-AI Filing Summary

Klaviyo, Inc. Co-CEO Andrew Bialecki reported an exercise-and-sell transaction involving 200,000 shares. On May 19, 2026, he converted 200,000 shares of Series B Common Stock into Series A Common Stock, then sold 200,000 Series A shares in open-market trades at a weighted average price of $14.88 per share, with individual sales between $14.68 and $15.41 per share.

These trades were executed under a pre-arranged Rule 10b5-1 trading plan adopted on May 20, 2025. After the transactions, Bialecki reports 66,944,118 shares of Series B Common Stock held directly, plus additional Series B shares held indirectly through family trusts and a grantor retained annuity trust, for which he disclaims beneficial ownership except for any pecuniary interest.

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Insider Bialecki Andrew
Role Co-Chief Executive Officer
Sold 200,000 shs ($2.98M)
Type Security Shares Price Value
Conversion Series B Common Stock 200,000 $0.00 --
Conversion Series A Common Stock 200,000 $0.00 --
Sale Series A Common Stock 200,000 $14.88 $2.98M
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 — 66,944,118 shares (Direct, null); Series A Common Stock — 200,000 shares (Direct, null); Series B Common Stock — 7,517,410 shares (Indirect, By The Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023)
Footnotes (1)
  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. 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. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $14.68 to $15.41 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. 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. 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. 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.
Shares sold 200,000 shares Series A Common Stock sold on May 19, 2026
Weighted average sale price $14.88 per share Open-market sales of Series A Common Stock
Sale price range $14.68–$15.41 per share Range of prices for the 200,000 Series A shares sold
Direct Series B holdings 66,944,118 shares Series B Common Stock held directly after transactions
Spouse-held Series B 43,218 shares Series B Common Stock held by spouse
Irrevocable GST trusts’ Series B 517,006 shares each Series B held by two 2023 irrevocable GST trusts
GRAT Series B holdings 7,517,410 shares Series B held by the 2023 Grantor Retained Annuity Trust
Rule 10b5-1 trading plan regulatory
"These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted..."
A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.
Grantor Retained Annuity Trust financial
"Shares held by the Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023..."
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
"Shares held by the Elizabeth L. Bialecki Irrevocable GST Trust of 2023..."
Section 16 beneficial ownership regulatory
"The Reporting Person disclaims Section 16 beneficial ownership of such shares except to the extent of his pecuniary interest..."
Series B Common Stock financial
"Each share of the Issuer's Series B Common Stock, par value $0.001 per share..."
Series A Common Stock financial
"is convertible at any time at the option of the holder into one share of the Issuer's Series A Common Stock..."
Series A common stock is a specific class of a company’s ordinary shares issued during an early formal funding round, carrying the ownership rights and voting power tied to that class. For investors it signals an early-stage equity claim with potential upside if the business grows, but also greater risk and typically less liquidity than shares in mature, publicly traded firms—imagine buying a seat on a startup’s team before the company has proven itself.
SEC Form 4
FORM 4UNITED 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)
XDirectorX10% Owner
XOfficer (give title below)Other (specify below)
Co-Chief Executive Officer
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
05/19/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm 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)
CodeVAmount(A) or (D)Price
Series A Common Stock05/19/2026C(1)200,000A(2)200,000D
Series A Common Stock05/19/2026S(1)200,000D$14.88(3)0D
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Series B Common Stock(2)05/19/2026C(1)200,000 (2) (2)Series A Common Stock200,000$066,944,118D
Series B Common Stock(2) (2) (2)Series A Common Stock7,517,4107,517,410IBy The Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023(4)
Series B Common Stock(2) (2) (2)Series A Common Stock517,006517,006IBy The Elizabeth L. Bialecki Irrevocable GST Trust of 2023(5)
Series B Common Stock(2) (2) (2)Series A Common Stock517,006517,006IBy The Andrew P. Bialecki Irrevocable GST Trust of 2023(6)
Series B Common Stock(2) (2) (2)Series A Common Stock43,21843,218IBy 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 $14.68 to $15.41 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-Fact05/20/2026
** Signature of Reporting PersonDate
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)

FAQ

What did Klaviyo (KVYO) Co-CEO Andrew Bialecki report in this Form 4?

Andrew Bialecki reported converting 200,000 shares of Series B Common Stock into Series A and selling 200,000 Series A shares. The sale used a weighted average price of $14.88 per share, with trades between $14.68 and $15.41.

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

He sold 200,000 shares of Series A Common Stock in open-market transactions at a weighted average price of $14.88 per share. Individual trades occurred within a price range from $14.68 to $15.41 per share.

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

Yes. The Form 4 states the transactions were effected under a Rule 10b5-1 trading plan adopted on May 20, 2025. Such pre-arranged plans schedule trades in advance, making their timing less indicative of short-term market views.

How many Klaviyo (KVYO) shares does Andrew Bialecki hold directly after the transactions?

Following the reported transactions, Andrew Bialecki holds 66,944,118 shares of Klaviyo’s Series B Common Stock directly. These Series B shares are convertible into Series A Common Stock on a one-for-one basis and have no expiration date.