Tectonic Therapeutic Inc. (TECX) Ownership
TECX ownership summary
as of October 18, 2026- Institutions
- 72.0% of shares outstanding
- Insiders
- 37.60% of shares outstanding
- Shares outstanding
- 19.5M
- Float
- 11.9M shares available to trade
- Short interest
- 22.99% 2.2M shares short
- Days to cover
- 8.84 short interest up 0.2% vs prior month
- Institutions 71.98%
- Insiders 37.60%
TECX top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | FMR Inc | 14.48% | 2.8M | $58.4M | +13,884 (+0.5%) | June 30, 2026 |
| 2 | TCG Crossover Management, LLC | 6.16% | 1.2M | $24.9M | — | June 30, 2026 |
| 3 | Aberdeen Group PLC | 5.84% | 1.1M | $23.6M | — | June 30, 2026 |
| 4 | BlackRock Inc | 4.41% | 863K | $17.8M | +2,240 (+0.3%) | June 30, 2026 |
| 5 | First Light Asset Management, LLC | 4.10% | 801K | $16.5M | +152,983 (+23.6%) | June 30, 2026 |
| 6 | Baker Bros Advisors LP | 3.11% | 608K | $12.6M | — | June 30, 2026 |
| 7 | 5AM Venture Management, LLC | 3.10% | 607K | $12.5M | — | June 30, 2026 |
| 8 | BRAIDWELL LP | 3.05% | 597K | $12.3M | −250,251 (−29.5%) | June 30, 2026 |
| 9 | Vanguard Capital Management, LLC | 2.50% | 489K | $10.1M | +15,273 (+3.2%) | June 30, 2026 |
| 10 | Vestal Point Capital LP | 2.17% | 425K | $8.8M | +97,000 (+29.6%) | June 30, 2026 |
| 11 | Bollard Group LLC | 1.55% | 303K | $6.3M | — | June 30, 2026 |
| 12 | Kennedy Capital Management Inc | 1.44% | 282K | $5.8M | −4,480 (−1.6%) | June 30, 2026 |
| 13 | Geode Capital Management, LLC | 1.38% | 270K | $5.6M | +2,188 (+0.8%) | June 30, 2026 |
| 14 | Orbimed Advisors LLC | 1.16% | 227K | $4.7M | — | June 30, 2026 |
| 15 | State Street Corp | 1.12% | 220K | $4.5M | +6,403 (+3.0%) | June 30, 2026 |
| 16 | Ikarian Capital, LLC | 1.05% | 206K | $4.3M | +48,300 (+30.7%) | June 30, 2026 |
| 17 | D. E. Shaw & Co LP | 0.95% | 187K | $3.9M | +70,430 (+60.7%) | June 30, 2026 |
| 18 | Marshall Wace Asset Management Ltd | 0.88% | 172K | $3.6M | −57,494 (−25.0%) | June 30, 2026 |
| 19 | Millennium Management LLC | 0.85% | 166K | $3.4M | +107,177 (+183.7%) | June 30, 2026 |
| 20 | Squarepoint Ops LLC | 0.74% | 145K | $3.0M | −19,391 (−11.8%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 10 holders added 516K shares and 4 cut 332K.
TECX top mutual fund and ETF holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Fidelity Growth Company Fund | 3.86% | 754K | $15.6M | +35,044 (+4.9%) | August 31, 2026 |
| 2 | Fidelity Select Biotechnology | 2.07% | 405K | $8.4M | — | August 31, 2026 |
| 3 | Vanguard MStar Total Stk Mkt Idx Invest | 1.86% | 364K | $7.5M | — | August 31, 2026 |
| 4 | iShares Russell 2000 ETF | 1.38% | 270K | $5.6M | −3,136 (−1.1%) | September 30, 2026 |
| 5 | abrdn Healthcare Investors | 1.33% | 260K | $5.4M | −278,318 (−51.7%) | August 31, 2026 |
| 6 | Fidelity Growth Company K6 | 1.33% | 260K | $5.4M | +10,509 (+4.2%) | August 31, 2026 |
| 7 | Fidelity Series Growth Company | 1.05% | 206K | $4.2M | +9,115 (+4.6%) | August 31, 2026 |
| 8 | abrdn Life Sciences Investors | 0.76% | 149K | $3.1M | −127,507 (−46.0%) | August 31, 2026 |
| 9 | Columbia Small Cap Growth Inst | 0.62% | 121K | $2.5M | — | August 31, 2026 |
| 10 | Fidelity Advisor Biotechnology I | 0.62% | 121K | $2.5M | — | August 31, 2026 |
| 11 | Fidelity Small Cap Index | 0.57% | 112K | $2.3M | +1,193 (+1.1%) | July 31, 2026 |
| 12 | iShares Russell 2000 Value ETF | 0.43% | 84K | $1.7M | +126 (+0.2%) | September 30, 2026 |
| 13 | Biotech Growth Ord | 0.40% | 77K | $1.6M | — | June 30, 2026 |
| 14 | iShares Biotechnology ETF | 0.38% | 74K | $1.5M | −560 (−0.8%) | September 30, 2026 |
| 15 | Vanguard Russell 2000 ETF | 0.30% | 59K | $1.2M | +1,481 (+2.6%) | August 31, 2026 |
| 16 | Fidelity Extended Market Index | 0.25% | 48K | $1.0M | −260 (−0.5%) | August 31, 2026 |
| 17 | iShares Micro-Cap ETF | 0.17% | 34K | $706,602 | −236 (−0.7%) | September 30, 2026 |
| 18 | Northern Small Cap Value | 0.15% | 28K | $586,625 | +28,408 (0.0%) | June 30, 2026 |
| 19 | ALPS Medical Breakthroughs ETF | 0.13% | 26K | $534,546 | — | September 30, 2026 |
| 20 | Vanguard Health Care ETF | 0.13% | 26K | $531,593 | +108 (+0.4%) | August 31, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
TECX insider transactions
latest 6| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2026-04-01 | Marcella K Ruddy | Sell | $31.05 | 1,000 | $31,050 |
| 2026-03-06 | Marcella K Ruddy | Sell | $30.00 | 10,000 | $300,000 |
| 2026-03-06 | Peter Mcnamara | Sell | $30.17 | 6,262 | $188,925 |
| 2026-03-04 | Peter Mcnamara | Sell | $25.00 | 1,650 | $41,250 |
| 2026-03-03 | Peter Mcnamara | Sell | $22.06 | 1,649 | $36,377 |
| 2026-02-10 | Daniel Lochner | Buy | $21.61 | 6,000 | $129,660 |
Reported trades by company officers, directors and other filers (including disclosures by members of Congress where EODHD lists them). "—" where the filing gives no share count.
TECX shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns TECX
Institutional investors own 72.0% of Tectonic Therapeutic's shares and insiders 37.60%. The largest holder is FMR Inc with 14.48% of the shares (2.8M), as of June 30, 2026. Among the top 20 institutions, 10 added shares and 4 reduced their stake in the latest filings. Short interest is 22.99% of the float, or 8.84 days of average trading volume. The share count rose 816.1% since 2016.
Related: TECX analyst forecast, TECX key metrics. See the TECX stock overview for the latest quote and news.
TECX ownership FAQ
Who owns the most Tectonic Therapeutic stock?
The largest shareholders of Tectonic Therapeutic are FMR Inc (14.48%), TCG Crossover Management, LLC (6.16%), Aberdeen Group PLC (5.84%), BlackRock Inc (4.41%), First Light Asset Management, LLC (4.10%).
What percentage of Tectonic Therapeutic is owned by institutions?
Institutions hold 72.0% of Tectonic Therapeutic's shares outstanding; insiders hold 37.60%.
Which funds own Tectonic Therapeutic?
The largest fund holders of Tectonic Therapeutic are Fidelity Growth Company Fund (3.86%), Fidelity Select Biotechnology (2.07%), Vanguard MStar Total Stk Mkt Idx Invest (1.86%), iShares Russell 2000 ETF (1.38%), abrdn Healthcare Investors (1.33%).
What is Tectonic Therapeutic's short interest?
2.2M shares of Tectonic Therapeutic were sold short, 22.99% of the float; at the average daily volume it would take 8.84 days to cover.
Are insiders buying or selling Tectonic Therapeutic?
Of the latest 6 reported insider transactions in Tectonic Therapeutic (since February 10, 2026), 1 were purchases and 5 were sales.
How many shares of Tectonic Therapeutic are outstanding?
Tectonic Therapeutic has 19.5M shares outstanding, of which 11.9M are in the public float.