Synlogic SYBX Insider Ownership

Updated Oct 5, 2026

Over the past year, SYBX insiders sold $284 of stock (157 shares) on the open market and bought none.

• Mary Beth Dooley (Officer) sold the most Synlogic stock on the open market over the past 12 months, $284 (157 shares), most recently on October 29, 2025.
• According to Business Quant data, insiders at Synlogic reported 43.25K shares in total in their latest Form 4 filings, unchanged from 43.25K shares at the end of Q2 2026.
• By type of ownership, SYBX insiders hold all of their 43.25K shares directly.
• Holdings in Synlogic stock are reported by 3 insiders, the officers, directors and 10% owners who have filed a Form 4 in the past two years.
• SYBX's three largest insider shareholders, per their latest Form 4 filings, are Richard P. Shea (Director, 15.51K shares), James P. Flynn (Director, 15K shares) and Mary Beth Dooley (Officer, 12.74K shares).
• Richard P. Shea alone accounts for 35.85% of the shares held by Synlogic insiders.
• Institutional investors held 0.19% of Synlogic stock at the end of Q2 2026, while the latest Form 4 filings of its insiders account for about 0.35%; other investors, including the public, hold roughly 99.46%.
• These insider figures for Synlogic are based on Form 4 filings through October 31, 2025.