SCHEDULE: Summit Partners Discloses 12.03% Stake in Klaviyo
Beneficial Ownership Report (Schedule 13G)
Summit Partners and its affiliated funds have reported a combined beneficial ownership of 12.03% in Klaviyo, Inc.'s Series A Common Stock.
Summary
- Summit Partners, L.P. and its affiliated entities (Summit Holders) collectively beneficially own 18,852,778 shares of Klaviyo, Inc.'s Series A Common Stock.
- This aggregate ownership represents 12.03% of the total outstanding Series A Common Stock.
- The calculation is based on 137,856,147 Series A Shares outstanding as of October 31, 2025, as reported in Klaviyo's Form 10-Q filed on November 5, 2025, plus the 18,852,778 Series A Shares issuable upon conversion of Series B Shares held by Summit Holders.
- Individual reporting persons include Summit Partners Growth Equity Fund IX-A, L.P. (11,142,414 shares, 7.11%), Summit Partners Growth Equity Fund IX-B, L.P. (6,957,168 shares, 4.44%), Summit Partners Co-Invest (Kiwi), L.P. (687,035 shares, 0.44%), Summit Investors GE IX/VC IV, LLC (58,561 shares, 0.04%), and Summit Investors GE IX/VC IV (UK), L.P. (7,600 shares, 0.01%).
- Summit Partners, L.P. is the ultimate controlling entity for these holdings through various general partner and manager relationships.
Sentiment
Score: 5
Explanation: This is a neutral, factual disclosure of beneficial ownership. It does not inherently convey positive or negative sentiment about the company's performance, but rather the investment position of a significant shareholder.
Future Outlook
NA
Industry Context
This filing indicates a significant, continued institutional investment in Klaviyo, a company operating in the marketing automation and customer data platform sector. Large stakes by private equity firms like Summit Partners are common in growth-oriented technology companies, reflecting confidence in long-term potential or a strategic investment position.
Related Party Transactions
- Summit Partners, L.P. and its affiliated funds are significant shareholders of Klaviyo, Inc., holding 12.03% of the Series A Common Stock. This establishes a related party relationship through substantial ownership.
Stakeholder Impact
- Shareholders: The disclosure of a significant institutional stake by Summit Partners may be viewed positively, indicating confidence from a major investor. It also highlights a large block of shares under common control.
- Management: Awareness of a significant institutional shareholder like Summit Partners can influence strategic decisions and corporate governance, as such investors often have a voice or influence.
Key Dates
| Date | Description |
|---|---|
| 2025-09-30 | Date of event requiring the filing of this statement. |
| 2025-10-31 | Date as of which Klaviyo's Series A Shares outstanding (137,856,147) were reported in its 10-Q. |
| 2025-11-05 | Date Klaviyo's Quarterly Report on Form 10-Q was filed with the SEC. |
| 2025-11-13 | Date of signature for the Schedule 13G Amendment No. 5. |
Keywords
Klaviyo, Summit Partners, Beneficial Ownership, Schedule 13G, Series A Common Stock, Institutional Investor, Equity Stake
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