Form 4: Klaviyo Co-CEO Bialecki Sells Shares Under 10b5-1 Plan

Klaviyo Co-CEO Andrew Bialecki reported the conversion of Series B to Series A common stock and subsequent sale of 200,000 Series A shares under a pre-arranged 10b5-1 trading plan.

Summary

• Andrew Bialecki, Co-Chief Executive Officer, Director, and 10% Owner of Klaviyo, Inc. (KVYO), reported transactions on February 24, 2026.
• The transactions involved the conversion of 200,000 shares of Series B Common Stock into 200,000 shares of Series A Common Stock.
• Immediately following the conversion, Bialecki sold all 200,000 shares of Series A Common Stock.
• The sales were executed in two tranches: 160,356 shares at a weighted average price of $16.86 per share, and 39,644 shares at a weighted average price of $16.38 per share.
• These transactions were conducted pursuant to a Rule 10b5-1 trading plan adopted by Bialecki on May 20, 2025.
• Following these transactions, Bialecki directly beneficially owns 0 shares of Series A Common Stock and 68,750,945 shares of Series B Common Stock.
• Indirect beneficial ownership of Series B Common Stock includes 7,517,410 shares through the Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023, 517,006 shares through the Elizabeth L. Bialecki Irrevocable GST Trust of 2023, 517,006 shares through the Andrew P. Bialecki Irrevocable GST Trust of 2023, and 43,218 shares through his spouse.

Sentiment

Score: 5

Explanation: StockSavvy.ai views this as a neutral event. While it represents insider selling, the execution under a pre-arranged 10b5-1 plan mitigates concerns of opportunistic trading, and the amount sold is a small fraction of the Co-CEO's total beneficial ownership.

Positives

• The transactions were executed under a pre-arranged Rule 10b5-1 trading plan, which indicates a structured approach to managing equity holdings and reduces the perception of opportunistic selling.

Negatives

• The Co-CEO sold all 200,000 Series A shares acquired through conversion, representing a reduction in direct equity holdings, which could be interpreted by some investors as a move to diversify or realize gains.

Future Outlook

NA

Industry Context

StockSavvy.ai notes that the use of a Rule 10b5-1 trading plan for insider transactions is a common practice among corporate executives. These plans allow insiders to sell a predetermined number of shares at a predetermined time or price, providing an affirmative defense against claims of insider trading and facilitating personal financial planning.

Comparison to Industry Standards

• The execution of stock sales through a Rule 10b5-1 plan is a standard corporate governance practice for executives to manage their equity holdings while adhering to insider trading regulations. This mechanism is widely adopted across publicly traded companies to provide transparency and reduce the perception of opportunistic trading.

Stakeholder Impact

• Shareholders: May experience minor shifts in sentiment due to insider selling, although the planned nature of the transaction typically lessens negative interpretations.

Key Dates

Keywords

Klaviyo, KVYO, Andrew Bialecki, Insider Trading, Form 4, Stock Sale, 10b5-1 Plan, Co-CEO, Series A Common Stock, Series B Common Stock