David Tsao insider trades: BillionToOne (BLLN) stock buys and sales
Trades on the price chart
Daily close, with an arrow on each day they bought or sold
Companies
Where David reports to the SEC
Open-market buys and sales
9 trades reported on SEC Form 4, newest first
| Date | Stock | Type | Shares | Price | Value | Holding | Reported |
|---|---|---|---|---|---|---|---|
| Nov 2, 2026 | BLLN | ↓ Sell | 20,000 | $109.24 | $2.2M | Direct | Nov 4, 2026 (2d) |
| Oct 5, 2026 | BLLN | ↓ Sell | 20,000 | $108.15 | $2.2M | Direct | Oct 7, 2026 (2d) |
| Sep 24, 2026 | BLLN | ↓ Sell | 3,333 | $125.00 | $417K | Direct | Sep 28, 2026 (4d) |
| Sep 9, 2026 | BLLN | ↓ Sell | 20,000 | $98.77 | $2.0M | Direct | Sep 11, 2026 (2d) |
| Aug 25, 2026 | BLLN | ↓ Sell | 10,000 | $100.00 | $1.0M | Direct | Aug 27, 2026 (2d) |
| Aug 10, 2026 | BLLN | ↓ Sell | 10,000 | $92.86 | $929K | Direct | Aug 12, 2026 (2d) |
| Jul 13, 2026 | BLLN | ↓ Sell | 20,000 | $124.88 | $2.5M | Direct | Jul 15, 2026 (2d) |
| Jun 15, 2026 | BLLN | ↓ Sell | 20,000 | $102.27 | $2.0M | Direct | Jun 17, 2026 (2d) |
| Nov 7, 2025 | BLLN | ↑ Buy | 1,000 | $60.00 | $60K | Direct | Nov 12, 2025 (5d) |
Each row is one filing's trades in one stock, summed. Shares and prices are as filed, before any later stock split.
Other BLLN insiders
Open-market trades in the last 12 months
About David Tsao's insider trades
David Tsao is Chief Technology Officer at BillionToOne (BLLN). Since Nov 7, 2025, David has reported 1 open-market purchase worth $60K and 8 sales worth $13.2M on SEC Form 4. In the last 12 months: 1 buy ($60K) and 8 sales ($13.2M).
Their filings also include option exercises (8 filings), gifts (1 filing), conversions (1 filing), other transactions (1 filing). These aren't open-market trades and aren't counted above.
How to read insider trades
Officers, directors and owners of more than 10% of a company must report trades in its stock on SEC Form 4, usually within two business days. Purchases with their own money are the stronger signal: insiders sell for many reasons (taxes, diversification, a house), but buy for one. See every BLLN insider trade, the latest insider trades across the market, or cluster buys, when several insiders buy the same stock within days.