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

Klaviyo CEO Andrew Bialecki sold 142,997 shares of Series A Common Stock on December 2 and December 4, 2025, under a pre-arranged 10b5-1 trading plan.

Summary

• Andrew Bialecki, Klaviyo's Chief Executive Officer, Director, and 10% Owner, reported transactions involving the company's stock.
• On December 2, 2025, Bialecki converted 142,045 shares of Series B Common Stock into Series A Common Stock and subsequently sold these 142,045 Series A Common Stock shares at a weighted average price of $28.62 per share.
• On December 4, 2025, Bialecki converted an additional 952 shares of Series B Common Stock into Series A Common Stock and sold these 952 Series A Common Stock shares at a price of $30.00 per share.
• All reported transactions were executed pursuant to a Rule 10b5-1 trading plan adopted by Bialecki on May 20, 2025.
• Following these transactions, Bialecki directly holds 0 shares of Series A Common Stock and 73,557,899 shares of Series B Common Stock.
• Bialecki also holds indirect beneficial ownership of Series B Common Stock through various trusts and his spouse, totaling 8,594,640 shares.

Sentiment

Score: 5

Explanation: Neutral. The filing reports insider selling, which can be viewed negatively, but the transactions were pre-scheduled under a 10b5-1 plan, mitigating immediate negative implications.

Positives

• The transactions were executed under a Rule 10b5-1 trading plan adopted on May 20, 2025, indicating pre-planned sales rather than opportunistic selling based on immediate non-public information.

Negatives

• The CEO, a director and 10% owner, sold a significant number of shares (142,997 Series A Common Stock), which could be interpreted by the market as a lack of confidence or a belief that the stock is fully valued.

Risks

• Insider selling, even under a 10b5-1 plan, can sometimes be perceived negatively by the market, potentially leading to downward pressure on the stock price due to investor sentiment regarding management's view of future prospects or valuation.

Future Outlook

This filing does not provide any forward-looking statements or guidance regarding the company's future performance or outlook.

Industry Context

This Form 4 filing reports individual insider transactions and does not provide broader industry trends or competitive analysis. The transactions reflect a personal financial decision by the CEO, pre-arranged under a 10b5-1 plan.

Related Party Transactions

• Andrew P. Bialecki holds indirect beneficial ownership of 7,517,410 Series B Common Stock shares through the Andrew P. Bialecki Grantor Retained Annuity Trust I of 2023, for which he serves as trustee.
• Andrew P. Bialecki holds indirect beneficial ownership of 517,006 Series B Common Stock shares through the Elizabeth L. Bialecki Irrevocable GST Trust of 2023, for which he serves as a trustee.
• Andrew P. Bialecki holds indirect beneficial ownership of 517,006 Series B Common Stock shares through the Andrew P. Bialecki Irrevocable GST Trust of 2023, for which his spouse serves as a trustee.
• Andrew P. Bialecki holds indirect beneficial ownership of 43,218 Series B Common Stock shares through his spouse.

Stakeholder Impact

• Shareholders may react to the insider selling, potentially influencing short-term stock price movements, although the pre-arranged nature of the 10b5-1 plan may temper negative sentiment.
• Employees, customers, suppliers, and creditors are unlikely to be directly impacted by this specific insider transaction report.

Key Dates

Recommendation

The CEO's sale of shares, while executed under a pre-arranged 10b5-1 plan, represents a significant insider transaction. While 10b5-1 plans are designed to avoid accusations of trading on material non-public information, large insider sales can still be interpreted by the market as a signal that the insider believes the stock is adequately valued or that they require personal liquidity. Given the absence of other company-specific news in this filing, a 'hold' recommendation is prudent, advising investors to monitor future company performance and market sentiment.

Keywords

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