Biotech Insider Buying: September 2026 Roundup

Over the last 30 days, 59 insider purchases were filed across 21 biotech companies. These are open-market buys only — we filter out routine 10b5-1 plan transactions, option exercises, and other noise using AI classification. Insider purchases in biotech small-caps carry more signal value than in large-caps, because the information asymmetry is higher. A CEO buying shares 3 weeks before a PDUFA date is making a bet with their own money — and research shows these "opportunistic" purchases predict abnormal returns.

- [HELP](/company/help) (CYBIN INC.): 7 buys totaling $8.4M — Chief Executive Officer Halstead Michael at $13.47/share - [ALMS](/company/alms) (ALUMIS INC.): 3 buys totaling $8.3M — Director AKKARAJU SRINIVAS at $10.63/share - [INBX](/company/inbx) (Inhibrx Biosciences, Inc.): 14 buys totaling $5.5M — Chief Executive Officer Lappe Mark at $112.28/share - [TENX](/company/tenx) (TENAX THERAPEUTICS, INC.): 5 buys totaling $1.7M — 10% Owner ADAR1 Capital Management, LLC at $1.78/share - [RLMD](/company/rlmd) (RELMADA THERAPEUTICS, INC.): 4 buys totaling $1.7M — Chief Financial Officer Shenouda Maged at $4.20/share - [EIKN](/company/eikn) (Eikon Therapeutics, Inc.): 1 buy totaling $1.0M — 10% Owner Column Group IV GP, LP at $11.56/share - [ATEC](/company/atec) (Alphatec Holdings, Inc.): 1 buy totaling $1.0M — CEO Miles Patrick at $8.81/share - [PRTA](/company/prta) (Prothena Corporation plc): 1 buy totaling $843K — 10% Owner SCULLY WILLIAM P at $8.43/share - [DMRA](/company/dmra) (Damora Therapeutics, Inc.): 1 buy totaling $253K — Director, President and CEO Jarrett Jennifer at $20.23/share - [NAMSW](/company/namsw) (NewAmsterdam Pharma Co N.V.): 1 buy totaling $227K — Chief Executive Officer Davidson Michael H. at $22.65/share - [TELA](/company/tela) (TELA Bio, Inc.): 4 buys totaling $167K — Director Capper Joseph H at $1.17/share - [CTSO](/company/ctso) (Cytosorbents Corp): 7 buys totaling $120K — Chief Executive Officer Chan Phillip P. at $0.35/share - [TMDX](/company/tmdx) (TransMedics Group, Inc.): 1 buy totaling $109K — Director Weill David at $81.63/share - [HCAT](/company/hcat) (Health Catalyst, Inc.): 1 buy totaling $105K — Chief Executive Officer Kohl Simeon at $1.79/share - [ANNX](/company/annx) (Annexon Biosciences Inc.): 1 buy totaling $100K — PRESIDENT AND CEO Love Douglas at $3.83/share For the full list of filtered insider trades, see the insider signals page.

Not all insider purchases are equal. The strongest signals come from: 1. C-suite executives (CEO, CFO, CMO) rather than 10% institutional owners 2. Open-market purchases rather than option exercises or plan-based transactions 3. Dollar amounts that are material relative to the insider's compensation 4. Timing near catalysts (PDUFA dates, readout windows) where the insider has informational advantage 5. Cluster buys where multiple insiders at the same company buy within a short window BiotechEdge automatically classifies insider transactions and filters out noise so you see only the conviction-driven buys. See our research on Form 4 insider trading for the academic evidence behind this approach. *This article is generated from SEC EDGAR Form 4 filings and does not constitute investment advice.*