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TNDM in the 13F filings

Tandem Diabetes Care Inc · CUSIP 875372203

Sector · Medical devices and instrumentsTheme · Healthcare: biopharma and medtech· L3VLUP-definedTheme · Surgical, medical and electromedical devices
Quarter
Q2 2026Q1 2026Q4 2025Q3 2025Q2 2025Q1 2025Q4 2024Q3 2024Q2 2024Q1 2024Q4 2023Q3 2023
Quarter end
31 Dec 2025
the date the book describes
Filed
27 Oct 2026
latest of these filings; the earliest 23 Jan 2026
Managers listing it
30
at least, of 95 tracked, among listed positions
Comparable managers
92
filed both Q3 2025 and Q4 2025; 5 listed it in both
Shares listed
12,370,699
combined, among listed positions
Reported value
$272m
combined, at the quarter end

Among the 92 comparable managers: 13 buyers (opened or added shares) and 19 sellers (trimmed or exited), at least, among listed positions. Their net change in shares was +1,093,798.

Managers listing TNDM in Q4 2025

Share of 13F value is the position’s reported value over everything the manager reported that quarter. The share change is against Q3 2025, and only where both filings list the position. A rise in value with no rise in shares is the price, not buying.

30 of 30 holders

ActionFiling
Citadel Advisors LLC2,088,603$46munder 0.1%Added+2,048,80217 Feb 2026 (the filing on sec.gov)
Freestone Grove Partners LP1,442,836$32m0.23%Trimmed-427,47117 Feb 2026 (the filing on sec.gov)
Two Sigma Investments LP1,201,527$26munder 0.1%Added+84,32517 Feb 2026 (the filing on sec.gov)
Baillie Gifford & Co1,145,516$25munder 0.1%Added+24,92123 Jan 2026 (the filing on sec.gov)
Two Sigma Advisers LP937,983$21munder 0.1%Trimmed-32,90017 Feb 2026 (the filing on sec.gov)
Marshall Wace LLP875,531$19munder 0.1%Newnew13 Feb 2026 (the filing on sec.gov)
D. E. Shaw & Co.854,266$19munder 0.1%Trimmed-22,95117 Feb 2026 (the filing on sec.gov)
Fidelity (FMR LLC)672,647$15munder 0.1%Trimmed-197,47617 Feb 2026 (the filing on sec.gov)
Millennium Management LLC583,573$13munder 0.1%Trimmed-122,32917 Feb 2026 (the filing on sec.gov)
Acadian Asset Management LLC392,763$8.6munder 0.1%Trimmed-525,96010 Feb 2026 (the filing on sec.gov)
AQR Capital Management LLC339,579$7.5munder 0.1%Trimmed-75,56617 Feb 2026 (the filing on sec.gov)
Invesco Ltd277,722$6.1munder 0.1%Trimmed-24,31919 Feb 2026 (the filing on sec.gov)
Balyasny Asset Management LLC262,788$5.8munder 0.1%Newnew17 Feb 2026 (the filing on sec.gov)
AllianceBernstein LP234,293$5.2munder 0.1%Added+10,57317 Feb 2026 (the filing on sec.gov)
Jane Street Group LLC209,975$4.6munder 0.1%Trimmed-7,33612 Feb 2026 (the filing on sec.gov)
Arrowstreet Capital LP135,753$3.0munder 0.1%Newnew13 Feb 2026 (the filing on sec.gov)
Susquehanna International Group LLP130,321$2.9munder 0.1%Trimmed-44,77517 Feb 2026 (the filing on sec.gov)
PDT Partners LLC110,385$2.4m0.16%Trimmed-60,03517 Feb 2026 (the filing on sec.gov)
Tudor Investment Corp108,063$2.4munder 0.1%Newnew17 Feb 2026 (the filing on sec.gov)
Wellington Management Group LLP98,309$2.2munder 0.1%Newnew17 Feb 2026 (the filing on sec.gov)
T. Rowe Price Associates Inc56,809$1.2munder 0.1%Trimmed-8,99417 Feb 2026 (the filing on sec.gov)
Winton Group Ltd44,244$972kunder 0.1%Newnew11 Feb 2026 (the filing on sec.gov)
Brevan Howard Capital Management LP34,091$749kunder 0.1%Trimmed-92,79717 Feb 2026 (the filing on sec.gov)
Quantbot Technologies LP32,956$724kunder 0.1%Trimmed-58010 Feb 2026 (the filing on sec.gov)
Janus Henderson Group Ltd29,811$655kunder 0.1%Held017 Feb 2026 (the filing on sec.gov)
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Largest increases and reductions, by shares

Q3 2025 to Q4 2025, 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.

New (8)

Exited (3)

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.
7 in Q3 2024 to 6 in Q2 2026

Tracked managers listing it, at least.

05101520201820192020202120222023202420252026
the quarter shown share split complete books; unmarked quarters rest on listed positionsClick a quarter to open it.
TNDM by quarter
QuarterHoldersReported valueBuyersSellers
Q1 20181$5.0mn.a.n.a.
Q2 20182$50mn.a.n.a.
Q3 20185$172mn.a.n.a.
Q4 20186$179mn.a.n.a.
Q1 20199$226mn.a.n.a.
Q2 201910$206mn.a.n.a.
Q3 20197$259mn.a.n.a.
Q4 20194$232mn.a.n.a.
Q1 20209$944mn.a.n.a.
Q2 202010$1.7bnn.a.n.a.
Q3 202013$1.7bnn.a.n.a.
Q4 20206$1.1bnn.a.n.a.
Q1 20219$943mn.a.n.a.
Q2 202110$1.1bnn.a.n.a.
Q3 202113$1.5bnn.a.n.a.
Q4 202116$1.9bnn.a.n.a.
Q1 202213$1.4bnn.a.n.a.
Q2 202210$740mn.a.n.a.
Q3 20228$748mn.a.n.a.
Q4 202211$836mn.a.n.a.
Q1 202310$411mn.a.n.a.
Q2 20239$306mn.a.n.a.
Q3 20236$256mn.a.n.a.
Q4 20238$388m26
Q1 20249$426m45
Q2 20247$332m33
Q3 20247$295m25
Q4 202410$188m72
Q1 20254$44m12
Q2 20257$74m51
Q3 20256$64m41
Q4 20255$81m1319
Q1 20265$69m1615
Q2 20266$73m1812

Compare with…

Holders over time, buyers and sellers, and the managers holding both, side by side for up to four stocks.

TNDM and LLY →TNDM and JNJ →TNDM and VRTX →Choose a stock to compare with TNDM →

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 TNDM, latest filings →Back to the 13F Explorer →