SCHEDULE: Klaviyo Co-Founder Andrew Bialecki Boosts Stake to 35.1%

Andrew Bialecki, co-founder of Klaviyo, Inc., has reported beneficial ownership of 35.1% of the company's Series A common stock as of December 31, 2025.

Summary

• Andrew Bialecki, co-founder of Klaviyo, Inc., reported beneficial ownership of 78,163,529 shares of Series A Common Stock.
• This ownership represents 35.1% of the total Series A Common Stock outstanding.
• The shares are held directly by Mr. Bialecki, by his spouse, and through various trusts including the Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023, the Andrew P. Bialecki Irrevocable GST Trust of 2023, and the Elizabeth L. Bialecki Irrevocable GST Trust of 2023.
• Mr. Bialecki holds sole voting and dispositive power over all 78,163,529 beneficially owned shares.
• This filing is an Amendment No. 3 to Schedule 13G, updating beneficial ownership information as of December 31, 2025.

Sentiment

Score: 8

Explanation: StockSavvy.ai views this as a strong positive signal, as significant insider ownership by a co-founder demonstrates high conviction in the company's future and aligns management's interests directly with long-term shareholder value.

Positives

• Significant insider ownership by co-founder Andrew Bialecki, holding 35.1% of Series A Common Stock, indicates strong confidence in the company's long-term prospects.
• High insider ownership often aligns management's interests directly with shareholder value, promoting a long-term strategic focus.
• The majority of shares (78,163,529) are under sole voting and dispositive power, indicating direct control and influence over company decisions.

Future Outlook

No forward-looking statements or guidance are provided in this beneficial ownership report.

Industry Context

StockSavvy.ai notes that substantial insider ownership, such as Andrew Bialecki's 35.1% stake in Klaviyo, is generally viewed positively by the market. It signals strong alignment between management's interests and shareholder value, a characteristic often seen in successful founder-led technology companies. This level of ownership can also provide stability and a long-term strategic focus, differentiating it from companies with more dispersed ownership.

Comparison to Industry Standards

• High insider ownership, like Bialecki's 35.1% in Klaviyo, is significantly above the average for publicly traded companies, where institutional and retail ownership typically dominates.
• For example, in many large-cap tech companies, founder stakes often dilute over time post-IPO to below 10-15%.
• This level of control is more akin to companies like Meta Platforms (Mark Zuckerberg's significant voting control) or Dell Technologies (Michael Dell's substantial stake), where founders maintain considerable influence over strategic direction.
• This concentration of ownership can be a double-edged sword, offering strong leadership but also potential for less independent board oversight.

Stakeholder Impact

• Shareholders: High insider ownership can instill confidence due to strong alignment of interests between management and shareholders.
• Employees: A stable ownership structure led by a co-founder may foster a consistent long-term vision for the company.

Key Dates

Recommendation

This Schedule 13G filing is a routine disclosure of beneficial ownership and does not contain new operational or financial information that would warrant a change in investment recommendation. However, the substantial 35.1% ownership by co-founder Andrew Bialecki is a positive indicator of strong insider confidence and alignment with long-term shareholder interests, reinforcing a 'hold' position for existing investors.

Keywords

Klaviyo, Andrew Bialecki, beneficial ownership, insider ownership, Schedule 13G, Series A Common Stock, KLVYO, SEC filing