X0508 4 2025-11-15 0 0001835830 Klaviyo, Inc. KVYO 0001991399 Edmond Landon C/O KLAVIYO, INC. 125 SUMMER STREET, 6TH FLOOR BOSTON MA 02110 0 1 0 0 Chief Legal Officer 0 Series A Common Stock 2025-11-15 4 C 0 11426 A 404010 D Series A Common Stock 2025-11-15 4 F 0 24218 28.61 D 379792 D Series A Common Stock 2025-11-17 4 C 0 11074 A 390866 D Series B Common Stock 2025-11-15 4 C 0 11426 0 D Series A Common Stock 11426 33574 D Series B Common Stock 2025-11-17 4 C 0 11074 0 D Series A Common Stock 11074 22500 D Represents 11,426 shares of the Issuer's Series B Common Stock, par value $0.001 per share ("Series B Common Stock"), automatically converted into shares of the Issuer's Series A Common Stock, par value $0.001 per share ("Series A Common Stock"), in connection with tax withholding obligations related to the vesting and settlement of restricted stock units ("RSUs"). Each share of Series B Common Stock is convertible at any time at the option of the holder into one share of 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. Represents shares of Series A Common Stock withheld by the Issuer to satisfy tax withholding obligations in connection with the vesting and settlement of RSUs. Consists of (i) 137,268 shares of Series A Common Stock and (ii) 253,598 unvested 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. Consists of 22,500 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. /s/ Landon Edmond 2025-11-18