Illumina Co-Founder David Walt Has Sold $114 Million in ILMN Stock — Now Buying Quanterix
David Walt, co-founder of Illumina's core bead array technology and director at Quanterix, has sold $114 million in ILMN stock across 4,807 transactions — while recently buying $1.4 million of QTRX shares.
David Walt, the scientist who co-invented the bead array technology at the heart of Illumina (ILMN), has filed 4,807 insider transactions totaling $114 million in career sales — but his most recent activity tells a different story: he’s buying heavily into Quanterix (QTRX).
The Numbers
| Metric | Value |
|---|---|
| Career Sell Value | $114.1M |
| Career Buy Value | $11.5M |
| Total Transactions | 4,807 |
| Last Transaction | 2026-01-02 |
| Shares Remaining | 1,872,890 (QTRX) |
Recent Activity
| Date | Type | Shares | Price | Est. Value |
|---|---|---|---|---|
| 2026-01-02 | Award | 1,215 | N/A | N/A (QTRX) |
| 2025-06-13 | Buy | 123,990 | $6.14 | $760,803 (QTRX) |
| 2025-06-12 | Buy | 36,010 | $6.23 | $224,166 (QTRX) |
| 2025-06-09 | Buy | 78,131 | $5.34 | $417,220 (QTRX) |
| 2025-06-06 | Buy | 131,869 | $5.43 | $716,576 (QTRX) |
Walt's 2025 activity is exclusively Quanterix. In June 2025 alone, he purchased 370,000 QTRX shares for approximately $2.1 million at prices between $5.34 and $6.23 per share. These are open-market purchases — not option exercises — signaling high-conviction buying in a $5-6 stock. He also receives quarterly director stock awards, accumulating 1.87 million shares total.
What It Means
Walt is a Tufts University professor and one of the key inventors behind Illumina's bead-based DNA sequencing technology, which helped make Illumina the dominant force in genomics. His $114 million in ILMN sales across 4,807 transactions reflects decades of systematic liquidation as Illumina grew from a startup to a $20+ billion market cap company.
The Quanterix pivot is notable: Walt is a co-founder and board member of the ultra-sensitive protein detection company (Simoa technology). His $1.4 million in open-market QTRX purchases at $5-6 per share — combined with 1.87 million shares — represents a significant bet on a company trading at a fraction of its 2021 highs above $70. For an insider who systematically sold $114M of one genomics company, his aggressive buying of another suggests strong conviction in Quanterix's single-molecule detection platform.
What to Watch
- Whether Walt continues open-market QTRX purchases — his June 2025 buying spree was unusually aggressive for a director
- Quanterix's stock trajectory — trading near $5-6 versus 2021 highs above $70 creates significant upside potential if the business recovers
- Walt's remaining Illumina exposure (if any) — his Form 4 filings now show QTRX as his primary company
- The broader trend of biotech founders rotating capital from mature platforms to early-stage companies
Breaking News Editor at 13F Insight. First to report on major SEC filings, institutional moves, and regulatory developments.
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