- Quarter end
- 31 Mar 2026
- the date the book describes
- Filed
- 27 Oct 2026
- latest of these filings; the earliest 12 May 2026
- Managers listing it
- 29
- at least, of 95 tracked, among listed positions
- Comparable managers
- 91
- filed both Q4 2025 and Q1 2026; 15 listed it in both
- Shares listed
- 43,973,671
- combined, among listed positions
- Reported value
- $7.2bn
- combined, at the quarter end
AllianceBernstein LP. Values in this filing are at the previous quarter end's prices; its share count is the quarter end's.
Among the 91 comparable managers: 16 buyers (opened or added shares) and 17 sellers (trimmed or exited), at least, among listed positions. Their net change in shares was +4,987,283.
Managers listing INSM in Q1 2026
29 of 29 holders
Largest increases and reductions, by shares
Increases
- Fidelity (FMR LLC)existing position · 13,160,167 shares now+3,232,231
- Artisan Partners LPexisting position · 6,527,301 shares now+1,683,552
- Capital World Investorsnew position · 1,362,291 shares now+1,362,291
- D. E. Shaw & Co.existing position · 5,625,825 shares now+1,274,830
- Citadel Advisors LLCexisting position · 2,182,571 shares now+1,025,276
Reductions
- Invesco Ltdexisting position · 6,512,889 shares now-1,005,449
- T. Rowe Price Associates Incexisting position · 3,092,807 shares now-946,659
- Two Sigma Investments LPexisting position · 237,017 shares now-725,139
- Janus Henderson Group Ltdexisting position · 419,304 shares now-381,251
- Balyasny Asset Management LLCexisting position · 221,707 shares now-158,854
New positions and exits
New (5)
Exited (4)
- Holocene Advisors LPwas $139m
- Freestone Grove Partners LPwas $6.3m
- Verition Fund Management LLCwas $2.8m
- Farallon Capital Management LLCwas $522k
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.
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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 →