David Tsao - SEC Form 4 Insider Trading Activity
Summary
Updated Aug 3, 2026
David Tsao has filed 2 SEC Form 4 filings across 1 company in the last 90 days - active on both sides. Lifetime open-market purchases: $60K. Lifetime open-market sales: $4.54M.
Profile
David Tsao is the Chief Technology Officer at BillionToOne, Inc. (BLLN). Tsao has reported 5 insider filings with the SEC since 2025. The most recent filing was in July 2026.
| Role | Chief Technology Officer, Director |
|---|---|
| Notability | 34/100 |
Board memberships
- BillionToOne, Inc.
Reported roles
- Chief Technology Officer
Trading Pattern
InsiderAlpha's records for David Tsao go back to 2025: 3 primary Form 4 filings, an average of 1.5 per year. The typical open-market purchase is $60K (1 buy totaling $60K). The largest single buy on record is $60K of BLLN in 2025. Sales side: 21 recorded sales totaling $4.54M, so the filing history runs sell-heavy by dollar value. 29 recorded transactions carry a Rule 10b5-1 flag, meaning they were pre-scheduled under a written trading plan rather than discretionary.
Career & Filing History
Every role David Tsao has reported on a Form 4, reconstructed from the filings themselves - reporting insiders must state their relationship to the issuer (officer title, director seat, or 10% ownership) on every filing.
- Chief Technology Officer, Director at BillionToOne, Inc. (BLLN) - 2 filings, 2026
- Chief Technology Officer at BillionToOne, Inc. (BLLN) - 1 filing, 2025
Recent Transactions
| Date | Ticker | Company | Code | Shares | Price | Value |
|---|---|---|---|---|---|---|
| 2026-07-15 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 1.0K | $126.90 | $130K |
| 2026-07-15 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 3.8K | $125.76 | $482K |
| 2026-07-15 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 1.7K | $124.65 | $215K |
| 2026-07-15 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 2.3K | $123.71 | $281K |
| 2026-07-15 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 1.1K | $122.84 | $140K |
| 2026-07-15 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 821 | $126.89 | $104K |
| 2026-07-15 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 3.2K | $125.85 | $401K |
| 2026-07-15 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 2.4K | $124.90 | $302K |
| 2026-07-15 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 2.5K | $123.84 | $307K |
| 2026-07-15 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 1.1K | $122.90 | $135K |
| 2026-07-15 | BLLN | BillionToOne, Inc. | M - Option exercise [10b5-1] | 10.0K | $2.80 | $28K |
| 2026-07-15 | BLLN | BillionToOne, Inc. | M - Option exercise [10b5-1] | 10.0K | $2.80 | $28K |
| 2026-06-17 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 563 | $104.32 | $59K |
| 2026-06-17 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 2.4K | $103.63 | $249K |
| 2026-06-17 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 3.0K | $102.60 | $306K |
| 2026-06-17 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 2.5K | $101.37 | $249K |
| 2026-06-17 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 1.0K | $100.05 | $100K |
| 2026-06-17 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 600 | $98.74 | $59K |
| 2026-06-17 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 230 | $104.47 | $24K |
| 2026-06-17 | BLLN | BillionToOne, Inc. | S - Open-market sale [10b5-1] | 2.9K | $103.68 | $300K |
Companies - Last 90 Days
- BillionToOne, Inc. (BLLN) - 2 filings, last 2026-07-15
Other Insiders Active in the Same Stocks
Insiders who reported open-market trades at the companies David Tsao has recently filed at. Multiple unrelated insiders buying the same stock within a short window - cluster buying - has historically been one of the strongest Form 4 signals.
- Oguzhan Atay - $10.10M of BLLN open-market activity in the last 12 months
- Nancy Joann Johnson - $3.74M of BLLN open-market activity in the last 12 months
- Shan Riku Sakakibara - $2.67M of BLLN open-market activity in the last 12 months
- Thomas S. Bremner - $2.50M of BLLN open-market activity in the last 12 months
- Bosch John Roderick Ten - $1.04M of BLLN open-market activity in the last 12 months
- Akshay Rai - $150K of BLLN open-market activity in the last 12 months
More Notable Insiders
Other corporate insiders with significant SEC Form 4 track records on InsiderAlpha:
- Charles A. Davis
- Deep Track Biotechnology Master Fund, Ltd.
- Robert E. Dixon
- Romeo R. Dizon
- Kevin Michael Donahue
- DONEGAL MUTUAL INSURANCE CO
- DORCHESTER MINERALS OPERATING LP
- Robert W. Duggan
Frequently Asked Questions
Who is David Tsao?
David Tsao is the Chief Technology Officer at BillionToOne, Inc. (BLLN). Tsao has reported 5 insider filings with the SEC since 2025. The most recent filing was in July 2026.…
How many SEC Form 4 filings has David Tsao submitted recently?
2 primary Form 4 filings in the last 90 days, covering 1 company.
Has David Tsao been buying or selling stock?
Recorded transactions: 1 open-market purchase ($60K) and 21 open-market sales ($4.54M) across all tracked filings.
Where can I see all of David Tsao's SEC filings?
All Form 4 filings, transaction values, and 10b5-1 plan flags are listed on this page and updated in real time as new SEC EDGAR filings are processed.
Learn More
Open the live David Tsao profile on InsiderAlpha for real-time alerts, AI-scored trade ideas, and full transaction history.