- Quarter end
- 30 Sep 2025
- the date the book describes
- Filed
- 17 Feb 2026
- latest of these filings; the earliest 12 Nov 2025
- Managers listing it
- 20
- at least, of 95 tracked, among listed positions
- Comparable managers
- 95
- filed both Q2 2025 and Q3 2025; 17 listed it in both
- Shares listed
- 40,121,099
- combined, among listed positions
- Reported value
- $5.8bn
- combined, at the quarter end
Among the 95 comparable managers: 10 buyers (opened or added shares) and 9 sellers (trimmed or exited), at least, among listed positions. Their net change in shares is not known from listed positions, because at least one of them lists it in only one of the two quarters.
Managers listing INSM in Q3 2025
20 of 20 holders
Largest increases and reductions, by shares
Increases
- Fidelity (FMR LLC)existing position · 9,180,963 shares now+4,087,702
- D. E. Shaw & Co.existing position · 5,657,464 shares now+2,234,845
- Artisan Partners LPexisting position · 4,937,683 shares now+1,623,342
- Two Sigma Investments LPexisting position · 772,780 shares now+396,272
- Millennium Management LLCexisting position · 2,336,112 shares now+214,395
Reductions
- T. Rowe Price Associates Incexisting position · 6,931,466 shares now-4,299,239
- Janus Henderson Group Ltdexisting position · 1,202,783 shares now-1,090,359
- Holocene Advisors LPexisting position · 1,083,681 shares now-933,125
- AllianceBernstein LPexisting position · 868,772 shares now-474,440
- Marshall Wace LLPexisting position · 658,647 shares now-454,714
New positions and exits
New (0)
No new position among listed positions.
Exited (0)
No exit shown by a manager’s own filing.
Ownership over time
Tracked managers listing it, at least.
| Quarter | Holders | Reported value | Buyers | Sellers |
|---|---|---|---|---|
| Q3 2013 | 1 | $20m | n.a. | n.a. |
| Q4 2013 | 1 | $28m | n.a. | n.a. |
| Q1 2014 | 2 | $39m | n.a. | n.a. |
| Q2 2014 | 2 | $43m | n.a. | n.a. |
| Q3 2014 | 1 | $34m | n.a. | n.a. |
| Q4 2014 | 1 | $44m | n.a. | n.a. |
| Q1 2015 | 1 | $174m | n.a. | n.a. |
| Q2 2015 | 1 | $211m | n.a. | n.a. |
| Q3 2015 | 1 | $168m | n.a. | n.a. |
| Q4 2015 | 2 | $169m | n.a. | n.a. |
| Q3 2016 | 1 | $146m | n.a. | n.a. |
| Q1 2017 | 1 | $189m | n.a. | n.a. |
| Q2 2017 | 4 | $180m | n.a. | n.a. |
| Q3 2017 | 7 | $890m | n.a. | n.a. |
| Q4 2017 | 4 | $954m | n.a. | n.a. |
| Q1 2018 | 3 | $428m | n.a. | n.a. |
| Q2 2018 | 3 | $475m | n.a. | n.a. |
| Q3 2018 | 4 | $416m | n.a. | n.a. |
| Q4 2018 | 1 | $150m | n.a. | n.a. |
| Q1 2019 | 4 | $897m | n.a. | n.a. |
| Q2 2019 | 6 | $559m | n.a. | n.a. |
| Q3 2019 | 6 | $284m | n.a. | n.a. |
| Q4 2019 | 6 | $680m | n.a. | n.a. |
| Q1 2020 | 7 | $472m | n.a. | n.a. |
| Q2 2020 | 7 | $1.0bn | n.a. | n.a. |
| Q3 2020 | 9 | $1.2bn | n.a. | n.a. |
| Q4 2020 | 8 | $1.0bn | n.a. | n.a. |
| Q1 2021 | 6 | $816m | n.a. | n.a. |
| Q2 2021 | 6 | $800m | n.a. | n.a. |
| Q3 2021 | 7 | $803m | n.a. | n.a. |
| Q4 2021 | 7 | $760m | n.a. | n.a. |
| Q1 2022 | 8 | $680m | n.a. | n.a. |
| Q2 2022 | 7 | $566m | n.a. | n.a. |
| Q3 2022 | 10 | $379m | n.a. | n.a. |
| Q4 2022 | 8 | $360m | n.a. | n.a. |
| Q1 2023 | 6 | $282m | n.a. | n.a. |
| Q2 2023 | 6 | $353m | n.a. | n.a. |
| Q3 2023 | 7 | $415m | n.a. | n.a. |
| Q4 2023 | 8 | $539m | 4 | 5 |
| Q1 2024 | 8 | $437m | 7 | 3 |
| Q2 2024 | 16 | $2.2bn | 10 | 6 |
| Q3 2024 | 18 | $2.3bn | 10 | 10 |
| Q4 2024 | 14 | $1.6bn | 4 | 8 |
| Q1 2025 | 14 | $1.9bn | 9 | 4 |
| Q2 2025 | 23 | $3.7bn | 17 | 6 |
| Q3 2025 | 20 | $5.8bn | 10 | 9 |
| Q4 2025 | 19 | $6.6bn | 14 | 20 |
| Q1 2026 | 19 | $7.0bn | 16 | 17 |
| Q2 2026 | 21 | $5.0bn | 28 | 11 |
Compare with…
Holders over time, buyers and sellers, and the managers holding both, side by side for up to four stocks.
INSM and LLY →INSM and JNJ →INSM and VRTX →Choose a stock to compare with INSM →
How much of the picture this is
A 13F is a manager’s long US-listed equity book at a quarter end, filed up to 45 days later. It shows no shorts, cash, bonds or performance, and it is never today’s portfolio. Large books are listed to their largest positions, so a manager missing from this table may still hold a small position below that line. These are 95 tracked managers, not the institutional market.
Which funds own INSM, latest filings →Back to the 13F Explorer →