SCHEDULE: Summit Partners Discloses Klaviyo Stake

Summit Partners, through various entities, has reported a beneficial ownership of 9.62% of Klaviyo, Inc.'s Series A Common Stock, totaling 13,852,778 shares.

Summary

• Summit Partners, via several affiliated entities, has filed a Schedule 13G, reporting a beneficial ownership of 13,852,778 shares of Klaviyo, Inc.'s Series A Common Stock.
• This represents a 9.62% ownership stake in the company.
• The reported shares are issuable in respect of Series B Common Stock held by the Summit entities.
• The calculation of outstanding shares is based on Klaviyo's Quarterly Report on Form 10-Q filed on November 4, 2026, which reported 130,150,680 Series A Shares outstanding as of October 31, 2026.
• The filing details the specific holdings of various Summit Partners entities, including Summit Partners Growth Equity Fund IX-A, L.P., Summit Partners Growth Equity Fund IX-B, L.P., Summit Partners Co-Invest (Kiwi), L.P., Summit Investors GE IX/VC IV, LLC, and Summit Investors GE IX/VC IV (UK), L.P.

Sentiment

Score: 6

Explanation: StockSavvy.ai views this filing as neutral to slightly positive, reflecting a significant but expected ownership stake by a major investment firm. The data itself is factual and does not indicate immediate positive or negative catalysts.

Positives

• Significant investment from a major financial firm (Summit Partners) indicates confidence in Klaviyo's long-term prospects.
• The ownership stake is substantial (9.62%), suggesting a strong alignment of interests between Summit Partners and Klaviyo.

Negatives

• The filing is an amendment to a previous filing, indicating ongoing adjustments to ownership, which could be a minor point of observation.
• The ownership is derived from Series B shares, which may have different rights or conversion terms compared to directly held Series A shares, though this is not detailed as a negative.

Risks

• Potential for future sales of shares by Summit Partners, which could impact the stock price.
• Changes in investment strategy by Summit Partners could lead to divestment or shifts in their stake.

Future Outlook

The filing itself does not contain forward-looking statements or guidance from Klaviyo. It is a disclosure of ownership by Summit Partners.

Industry Context

StockSavvy.ai notes that significant ownership filings by major investment firms like Summit Partners are common in the technology sector, particularly for growth-stage companies. This filing indicates a substantial, established position rather than a new development or strategic shift by Klaviyo itself.

Comparison to Industry Standards

• Ownership stakes of this magnitude (9.62%) by venture capital and private equity firms are typical in the technology sector, especially for companies that have recently gone public or are in a growth phase.
• Firms like Summit Partners often hold significant stakes in their portfolio companies for extended periods, aiming for long-term value appreciation.
• Competitors in the marketing technology space, such as HubSpot or Mailchimp (now Intuit), have different ownership structures, with HubSpot being publicly traded and Mailchimp being acquired.

Stakeholder Impact

• Shareholders: The substantial stake held by Summit Partners may provide a degree of stability to the stock price, but also indicates a significant block holder whose future actions (buying or selling) could influence the market.
• Klaviyo Management: The continued significant ownership by a major investor like Summit Partners suggests ongoing support and potential strategic guidance.
• Creditors: No direct impact indicated.

Next Steps

• Monitoring future filings by Summit Partners for any changes in their ownership stake.
• Observing Klaviyo's performance and strategic execution to assess the long-term value of Summit Partners' investment.

Key Dates

Keywords

Klaviyo, Summit Partners, Schedule 13G, Beneficial Ownership, Series A Common Stock, Series B Common Stock, Investment Fund, SEC Filing