Tandem Diabetes Care
TNDM
268 hedge funds and large institutions have $1.65B invested in Tandem Diabetes Care in 2025 Q4 according to their latest regulatory filings, with 52 funds opening new positions, 85 increasing their positions, 99 reducing their positions, and 32 closing their positions.
582% more call options, than puts
Call options by funds: $67M | Put options by funds: $9.83M
200% more funds holding in top 10
Funds holding in top 10: 1 → 3 (+2)
81% more capital invested
Capital invested by funds: $911M → $1.65B (+$734M)
63% more first-time investments, than exits
New positions opened: 52 | Existing positions closed: 32
5% more funds holding
Funds holding: 255 → 268 (+13)
0.7% less ownership
Funds ownership: 111.12% → 110.42% (-0.7%)
14% less repeat investments, than reductions
Existing positions increased: 85 | Existing positions reduced: 99
Top Buyers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
Citadel Advisors
Miami,
Florida
|
+$37M |
| 2 |
DCM
Driehaus Capital Management
Chicago,
Illinois
|
+$29.1M |
| 3 |
Morgan Stanley
New York
|
+$24.2M |
| 4 |
Assenagon Asset Management
Senningerberg,
Luxembourg
|
+$22.2M |
| 5 |
FLAM
First Light Asset Management
Edina,
Minnesota
|
+$19.7M |
Top Sellers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
HRCM
Hood River Capital Management
Palm Beach Gardens,
Florida
|
-$31M |
| 2 |
UBS Group
Zurich,
Switzerland
|
-$19.6M |
| 3 |
BlackRock
New York
|
-$17.2M |
| 4 |
ACH
ArrowMark Colorado Holdings
Denver,
Colorado
|
-$14.5M |
| 5 |
Acadian Asset Management
Boston,
Massachusetts
|
-$9.49M |
TNDM Hedge Fund Activity: Q4 2025 in Review
268 institutional investors reported a position in Tandem Diabetes Care (TNDM) for Q4 2025, worth a combined $1.65B — up 81% from $911M a quarter earlier.
Buyers outnumbered sellers: 52 funds opened new TNDM positions and 32 closed out — a net gain of 20 holders — while 85 added to existing stakes and 99 trimmed.
The largest buyer was Citadel Advisors, adding an estimated $37M. The largest seller was Hood River Capital Management, exiting entirely with an estimated $31M sold.
- 268 institutional investors held Tandem Diabetes Care (TNDM) as of Q4 2025, up from 255 in Q3 2025.
- Funds reported $1.65B of Tandem Diabetes Care stock for Q4 2025, up 81% quarter-over-quarter.
- 52 funds opened new Tandem Diabetes Care positions in Q4 2025 and 32 closed out, a net change of +20 holders.
- The largest Tandem Diabetes Care buyer in Q4 2025 was Citadel Advisors, an estimated $37M added.
- The largest Tandem Diabetes Care seller in Q4 2025 was Hood River Capital Management, an estimated $31M sold.
Based on aggregated 13F filings for Q4 2025.