X0609 4 2026-09-15 0 0001835830 Klaviyo, Inc. KVYO 0002050221 Smith Erica Ellen false C/O KLAVIYO, INC. 125 SUMMER STREET, 6TH FLOOR BOSTON MA 02110 0 1 0 0 Chief Financial Officer 0 Series A Common Stock 2026-09-15 4 A 0 821917 0 A 821917 D Series A Common Stock 2026-09-15 4 A 0 328767 0 A 1150684 D Represents restricted stock units ("RSUs") awarded under the Issuer's 2023 Stock Option and Incentive Plan (the "Plan"), each representing the contingent right to receive one share of the Issuer's Series A Common Stock, par value $0.001 per share ("Series A Common Stock"), upon vesting and settlement. The RSUs will vest in sixteen equal quarterly installments, with the first such installment vesting on February 15, 2027, subject to the Reporting Person's continued service on each such vesting date. Represents performance stock units ("PSUs") awarded under the Plan, each representing the contingent right to receive one share of Series A Common Stock upon vesting and settlement. The PSUs will vest in up to three tranches over a two and a half year measurement period, subject to the achievement of specified performance targets tied to the trading price of the Series A Common Stock and the Reporting Person's continued service in the same or substantially equivalent position as the Reporting Person held as of the grant date through the applicable vesting date. Each tranche of PSUs will vest only if the average closing price of the Series A Common Stock for a period of at least sixty consecutive calendar days is at or above a specified dollar value during the applicable measurement period. (continued) The stock price targets for tranches 1 through 3 are $30.00, $50.00, and $75.00 per share, respectively, subject to proportionate adjustment in the event of any stock split or other similar change in the Issuer's capital stock. Consists of (i) 821,917 unvested RSUs awarded under the Plan, each representing the contingent right to receive one share of Series A Common Stock upon vesting and settlement; and (ii) 328,767 unvested PSUs awarded under the Plan, each representing the contingent right to receive one share of Series A Common Stock upon vesting and settlement. /s/ Landon Edmond, Attorney-in-Fact 2026-09-17