Klaviyo Announces Pricing of Secondary Offering of 6,500,000 Shares of Series A Common Stock by Certain Selling Stockholders

BOSTON, August 18, 2025 — Klaviyo, Inc. (the “Company”) (NYSE: KVYO), the only CRM built for B2C brands, today announced the pricing of an underwritten public offering of 6,500,000 shares of its Series A common stock (the “Offering”) by certain of its existing stockholders (the “Selling Stockholders”). In addition, such Selling Stockholders have granted the underwriter a 30-day option to purchase up to an additional 975,000 shares. The Company will not receive any proceeds from the sale of the shares being offered by the Selling Stockholders. The Offering is expected to close on August 21, 2025, subject to customary closing conditions.

Barclays is acting as the underwriter for the offering.

Barclays may offer the shares of Series A common stock from time to time in one or more transactions on the New York Stock Exchange, in the over-the-counter market, through negotiated transactions or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or at negotiated prices.

A registration statement on Form S-3 relating to these securities was filed with the Securities and Exchange Commission (the “SEC”) on February 19, 2025 and became effective upon filing. The offering is being made only by means of a prospectus supplement and an accompanying prospectus. A copy of these documents may be obtained, when available, by visiting the SEC’s website at www.sec.gov or by contacting Barclays Capital Inc., c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717, by phone 1-888-603-5847, or by email: barclaysprospectus@broadridge.com.

This press release shall not constitute an offer to sell or a solicitation of an offer to buy these securities, nor shall there be any offer or sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such state or jurisdiction.