SCHEDULE: Zachary Hornby Reports 9.8% Stake in Boundless Bio

Zachary Hornby has disclosed beneficial ownership of 2,426,857 shares, representing 9.8% of Boundless Bio's common stock, as of August 17, 2026.

Summary

• Zachary Hornby has filed a Schedule 13G, reporting beneficial ownership of 2,426,857 shares of Boundless Bio, Inc. common stock.
• This ownership stake represents 9.8% of the company's outstanding common stock as of August 17, 2026.
• The reported shares include 456,410 shares held directly and 1,970,447 shares underlying vested stock options.
• The filing indicates that these shares were not acquired for the purpose of influencing the control of the issuer.

Sentiment

Score: 6

Explanation: StockSavvy.ai views this as a neutral filing, primarily reporting on beneficial ownership changes rather than significant operational or financial performance.

Positives

• Zachary Hornby's direct and indirect ownership stake of 9.8% indicates significant personal investment in Boundless Bio.
• The disclosure confirms that the shares are not held with the intent to influence company control, suggesting a passive investment approach.

Negatives

• The filing does not provide any financial performance data or operational updates, offering no insight into the company's current health.

Risks

• Potential for future changes in beneficial ownership that could impact stock price or control dynamics.
• The reliance on stock options for a significant portion of the reported shares introduces potential dilution if options are exercised.

Future Outlook

The filing does not contain any forward-looking statements or guidance regarding future performance.

Management Comments

• "By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under 240.14a-11."
• "After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct."

Industry Context

StockSavvy.ai notes that Schedule 13G filings are common for institutional investors and significant individual shareholders to report their holdings. This filing indicates a substantial, but not controlling, stake in Boundless Bio, a biotechnology company.

Stakeholder Impact

• Shareholders: The disclosure provides transparency on a significant ownership stake, which may influence market perception.
• Management: The filing confirms that the reported shares are not intended to influence control, which could be reassuring to current management.

Next Steps

• Continued monitoring of Zachary Hornby's beneficial ownership in Boundless Bio.
• Potential future filings if ownership levels change significantly.

Key Dates

Keywords

Beneficial Ownership, Schedule 13G, Zachary Hornby, Boundless Bio, Stock Options, Common Stock, SEC Filing