Klaviyo, Inc. reported an insider sale by Amanda Whalen involving the company’s Series A Common Stock. The Form 4, filed July 17, 2026, covers a transaction dated July 16, 2026. Whalen sold 14,000 shares of Klaviyo Series A Common Stock at a weighted average price of $17.75 per share. The sale was reported as an open-market sale transaction, commonly reflected on Form 4 with transaction code “S,” and represented approximate gross proceeds of $248,500 before any commissions, fees, or taxes. The filing notes that the shares were sold in multiple transactions at prices ranging from $17.43 to $18.05 per share. Because the reported price is a weighted average, Whalen undertook to provide detailed per-price transaction information to Klaviyo, any Klaviyo security holder, or SEC staff upon request. The transaction was executed under a Rule 10b5-1 trading plan adopted by Whalen on August 21, 2025. Such plans allow insiders to arrange future stock trades under preset instructions, generally intended to reduce concerns that trades are being made based on material nonpublic information. After the reported sale, Whalen’s reported ownership consisted of 59,302 shares of Klaviyo Series A Common Stock, plus 551,618 unvested restricted stock units and 227,272 unvested performance stock units awarded under Klaviyo’s 2023 Stock Option and Incentive Plan. Each RSU and PSU represents a contingent right to receive one share of Series A Common Stock upon vesting and settlement. The filing was signed on Whalen’s behalf by Landon Edmond as attorney-in-fact.