L3VLUP
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

Share of 13F value is the position’s reported value over everything the manager reported that quarter. The share change is against Q4 2025, and only where both filings list the position. A rise in value with no rise in shares is the price, not buying.

29 of 29 holders

ActionFiling
Fidelity (FMR LLC)13,160,167$2.2bn0.11%Added+3,232,23115 May 2026 (the filing on sec.gov)
Artisan Partners LP6,527,301$1.1bn1.71%Added+1,683,55213 May 2026 (the filing on sec.gov)
Invesco Ltd6,512,889$1.1bn0.10%Trimmed-1,005,44912 May 2026 (the filing on sec.gov)
D. E. Shaw & Co.5,625,825$920m0.55%Added+1,274,83015 May 2026 (the filing on sec.gov)
T. Rowe Price Associates Inc3,092,807$506m0.06%Trimmed-946,65915 May 2026 (the filing on sec.gov)
Citadel Advisors LLC2,182,571$357m0.06%Added+1,025,27615 May 2026 (the filing on sec.gov)
Capital World Investors1,362,291$223munder 0.1%Newnew13 May 2026 (the filing on sec.gov)
Millennium Management LLC1,157,786$189m0.08%Trimmed-153,86815 May 2026 (the filing on sec.gov)
AllianceBernstein LP688,734$120munder 0.1%Added+46,01515 May 2026 (the filing on sec.gov)
AQR Capital Management LLC675,485$109munder 0.1%Added+207,22515 May 2026 (the filing on sec.gov)
Janus Henderson Group Ltd419,304$69munder 0.1%Trimmed-381,25118 May 2026 (the filing on sec.gov)
Wellington Management Group LLP399,044$65munder 0.1%Trimmed-87,09415 May 2026 (the filing on sec.gov)
Marshall Wace LLP312,565$51m0.05%Trimmed-77,31615 May 2026 (the filing on sec.gov)
Bridgewater Associates LP295,579$48m0.22%Newnew15 May 2026 (the filing on sec.gov)
Neuberger Berman Group LLC270,700$44munder 0.1%Added+62,83127 Oct 2026 (the filing on sec.gov)
Two Sigma Investments LP237,017$39munder 0.1%Trimmed-725,13915 May 2026 (the filing on sec.gov)
Balyasny Asset Management LLC221,707$36munder 0.1%Trimmed-158,85415 May 2026 (the filing on sec.gov)
Susquehanna International Group LLP173,630$28munder 0.1%Trimmed-14,94615 May 2026 (the filing on sec.gov)
Woodline Partners LP148,453$24m0.09%Added+18,30115 May 2026 (the filing on sec.gov)
ExodusPoint Capital Management LP148,133$24m0.19%Added+68,04614 May 2026 (the filing on sec.gov)
Man Group PLC126,840$21munder 0.1%Added+8,47915 May 2026 (the filing on sec.gov)
Walleye Capital LLC71,819$12munder 0.1%Added+55,99913 May 2026 (the filing on sec.gov)
Schonfeld Strategic Advisors LLC56,056$9.2m0.06%Newnew15 May 2026 (the filing on sec.gov)
Squarepoint Ops LLC39,316$6.4munder 0.1%Trimmed-27,08615 May 2026 (the filing on sec.gov)
Voloridge Investment Management LLC32,190$5.3munder 0.1%Newnew15 May 2026 (the filing on sec.gov)
Page 1 of 2

Largest increases and reductions, by shares

Q4 2025 to Q1 2026, among managers that listed it in both quarters or opened it.

Increases

Reductions

New positions and exits

At least these many: a manager is shown exiting only where its own filing shows the position gone.

Ownership over time

Every quarter on file. A quarter-end value moves with the price as well as with the shares held; buyers and sellers count comparable managers, by shares.
18 in Q3 2024 to 21 in Q2 2026

Tracked managers listing it, at least.

0102030201420182020202220242026
the quarter shown share split complete books; unmarked quarters rest on listed positionsClick a quarter to open it.
INSM by quarter
QuarterHoldersReported valueBuyersSellers
Q3 20131$20mn.a.n.a.
Q4 20131$28mn.a.n.a.
Q1 20142$39mn.a.n.a.
Q2 20142$43mn.a.n.a.
Q3 20141$34mn.a.n.a.
Q4 20141$44mn.a.n.a.
Q1 20151$174mn.a.n.a.
Q2 20151$211mn.a.n.a.
Q3 20151$168mn.a.n.a.
Q4 20152$169mn.a.n.a.
Q3 20161$146mn.a.n.a.
Q1 20171$189mn.a.n.a.
Q2 20174$180mn.a.n.a.
Q3 20177$890mn.a.n.a.
Q4 20174$954mn.a.n.a.
Q1 20183$428mn.a.n.a.
Q2 20183$475mn.a.n.a.
Q3 20184$416mn.a.n.a.
Q4 20181$150mn.a.n.a.
Q1 20194$897mn.a.n.a.
Q2 20196$559mn.a.n.a.
Q3 20196$284mn.a.n.a.
Q4 20196$680mn.a.n.a.
Q1 20207$472mn.a.n.a.
Q2 20207$1.0bnn.a.n.a.
Q3 20209$1.2bnn.a.n.a.
Q4 20208$1.0bnn.a.n.a.
Q1 20216$816mn.a.n.a.
Q2 20216$800mn.a.n.a.
Q3 20217$803mn.a.n.a.
Q4 20217$760mn.a.n.a.
Q1 20228$680mn.a.n.a.
Q2 20227$566mn.a.n.a.
Q3 202210$379mn.a.n.a.
Q4 20228$360mn.a.n.a.
Q1 20236$282mn.a.n.a.
Q2 20236$353mn.a.n.a.
Q3 20237$415mn.a.n.a.
Q4 20238$539m45
Q1 20248$437m73
Q2 202416$2.2bn106
Q3 202418$2.3bn1010
Q4 202414$1.6bn48
Q1 202514$1.9bn94
Q2 202523$3.7bn176
Q3 202520$5.8bn109
Q4 202519$6.6bn1420
Q1 202619$7.0bn1617
Q2 202621$5.0bn2811

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 →