[Form 4] Klaviyo, Inc. Insider Trading Activity

Rhea-AI Filing Summary

A company officer completed multiple open-market transactions under a Rule 10b5-1 plan on 10/10/2025. The reporting person, the Chief Financial Officer, acquired 15,000 shares of Series B common stock and sold a total of 15,000 shares of Series A common stock in two blocks: 9,808 shares at a weighted-average price of $25.33 and 5,192 shares at a weighted-average price of $24.45. After these transactions the officer reports beneficial ownership of 481,719 shares of Series A common stock (including 439,032 unvested RSUs) and beneficial ownership of 393,476 derivative-linked shares (including 209,101 Series B shares and 184,375 unvested RSUs).

The filing discloses the trades were made pursuant to a 10b5-1 trading plan adopted on 8/16/2024, and notes that each Series B share converts into one Series A share. The reporting person signed the form via attorney-in-fact on 10/10/2025.

Positive

• Trades executed under a Rule 10b5-1 plan, providing procedural clarity and affirmative defense (plan dated 8/16/2024)
• Post-transaction beneficial ownership remains substantial: 481,719 Series A-equivalent shares including 439,032 unvested RSUs

Negative

• Officer sold 15,000 Series A shares (9,808 at a weighted-average $25.33 and 5,192 at $24.45), reducing immediate vested holdings
• Majority of reported holdings are unvested RSUs (439,032 Series A RSUs and 184,375 Series B RSUs), which are subject to vesting schedules and potential forfeiture

Insights

Corporate Governance Analyst

Officer used a pre-established plan to sell and buy company stock while retaining sizable equity exposure.

The reporting person executed sales and an acquisition under a Rule 10b5-1 trading plan adopted on 8/16/2024, which provides an affirmative defense against insider trading claims when properly implemented. The transaction mix shows partial liquidation of vested holdings alongside a conversion-capable purchase of 15,000 Series B shares, which convert one-for-one into Series A shares.

Dependency and risk center on ongoing vesting of RSUs and potential future conversion mechanics; monitor reported post-trade beneficial ownership and any future plan disclosures over the next 12 months for changes in insider ownership levels.

Equity Trading Analyst

Sales were executed at weighted-average prices between $24.45 and $25.33, indicating modest liquidity exits.

The filing shows two sale blocks totaling 15,000 Series A shares sold at weighted-average prices in the $24.25–$25.85 range across multiple trades. The seller retained >480k beneficially owned shares including significant unvested RSUs, so the transactions represent a small percentage of reported holdings.

Watch for additional scheduled 10b5-1 activity or open-market trades in the next few quarters to assess whether these were routine plan-driven sales or part of a larger liquidity pattern.

SEC Form 4

FORM 4

UNITED 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^*

Whalen Amanda

(Last) (First) (Middle)

C/O KLAVIYO, INC.

125 SUMMER STREET, 6TH FLOOR

(Street)

BOSTON MA 02110

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Klaviyo, Inc. [ KVYO ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Financial Officer

3. Date of Earliest Transaction (Month/Day/Year)
10/10/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

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)
			Code	V	Amount	(A) or (D)	Price
Series A Common Stock	10/10/2025		C(1)		15,000	A	(2)	496,719	D
Series A Common Stock	10/10/2025		S(1)		9,808	D	$25.33(3)	486,911	D
Series A Common Stock	10/10/2025		S(1)		5,192	D	$24.45(4)	481,719(5)	D

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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series B Common Stock	(2)	10/10/2025		C(1)			15,000	(2)	(2)	Series A Common Stock	15,000	$0	393,476(6)	D

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 August 16, 2024.

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 $24.93 to $25.85 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. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $24.25 to $24.73 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.

5. Consists of (i) 42,687 shares of Series A Common Stock and (ii) 439,032 unvested restricted stock units ("RSUs") awarded under the Issuer's 2023 Stock Option and Incentive Plan, each representing the contingent right to receive one share of Series A Common Stock upon vesting and settlement.

6. Consists of (i) 209,101 shares of Series B Common Stock and (ii) 184,375 unvested RSUs awarded under the Issuer's 2015 Stock Incentive Plan, each representing the contingent right to receive one share of Series B Common Stock upon vesting and settlement.

Remarks:

	/s/ Landon Edmond, Attorney-in-Fact	10/10/2025
	** Signature of Reporting Person	Date
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.

FAQ

What did the Klaviyo (KVYO) CFO trade on 10/10/2025?

The CFO acquired 15,000 Series B shares and sold 15,000 Series A shares in two blocks on 10/10/2025 under a 10b5-1 trading plan.

At what prices were the KVYO shares sold?

Sales were executed at weighted-average prices: 9,808 shares at $25.33 and 5,192 shares at $24.45; reported price ranges were $24.25–$24.73 and $24.93–$25.85 across multiple transactions.

How many Kvyo shares does the reporting person own after the transactions?

The filing reports 481,719 Series A-equivalent shares beneficially owned (including 439,032 unvested RSUs) and 393,476 Series B-equivalent derivative holdings in Table II.

Were the trades part of a Rule 10b5-1 plan?

Yes. The reporting person adopted a Rule 10b5-1 trading plan on 8/16/2024, and the transactions on 10/10/2025 were effected pursuant to that plan.

Do Series B shares convert to Series A shares?

Yes. Each Series B share converts at the holder's option into one Series A share and will automatically convert upon certain charter events; the Series B shares have no expiration date.