SCHEDULE 13G/A

Klaviyo Inc

Series A Common Stock, par value $0.001 per share · CUSIP: 49845K101

Event date: 2025-06-30

Reporting persons may disclose overlapping interests. Their amounts are shown individually and are not added into a filing total.

Filing-level shares

Unavailable

Percent of class

Unavailable

• Summit Partners Growth Equity Fund IX-A, L.P.

  Shares: 18,219,907.00 · Class: 12.33%

• Summit Partners Growth Equity Fund IX-B, L.P.

  Shares: 11,376,255.00 · Class: 7.70%

• Summit Partners Co-Invest (Kiwi), L.P.

  Shares: 1,123,429.00 · Class: 0.76%

• Summit Investors GE IX/VC IV, LLC

  Shares: 95,759.00 · Class: 0.06%

• Summit Investors GE IX/VC IV (UK), L.P.

  Shares: 12,428.00 · Class: 0.01%

• Summit Partners, L.P.

  Shares: 30,827,778.00 · Class: 20.87%

Amounts are as disclosed in this filing. Schedule type alone does not establish investment intent.