TANDEM DIABETES CARE INC TNDM
COM NEW · Common Stock · CUSIP 875372203 · ISIN US8753722037
U.S. healthcare company
- SectorHealth care
- IndustrySurgical & Medical Instruments & Apparatus
- HeadquartersSan Diego, CA
- Founded2008
- Websitetandemdiabetes.com
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($3.9m this quarter). Holder counts are more reliable. Shares outstanding: 67.8m as of 2025-11-04, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $21.98. Options: 11 managers hold calls ($67.0m notional), 11 hold puts ($9.8m).
Trends to Q4 2025
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q3 2022 | 298 |
| Q4 2022 | 295 |
| Q1 2023 | 275 |
| Q2 2023 | 248 |
| Q3 2023 | 226 |
| Q4 2023 | 268 |
| Q1 2024 | 291 |
| Q2 2024 | 316 |
| Q3 2024 | 331 |
| Q4 2024 | 315 |
| Q1 2025 | 276 |
| Q2 2025 | 272 |
| Q3 2025 | 255 |
| Q4 2025 | 268 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q1 2024 | 174 | 107 |
| Q2 2024 | 184 | 126 |
| Q3 2024 | 162 | 157 |
| Q4 2024 | 165 | 143 |
| Q1 2025 | 141 | 160 |
| Q2 2025 | 154 | 114 |
| Q3 2025 | 115 | 153 |
| Q4 2025 | 131 | 131 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q1 2025 | $61.6m | $5.5m | 0.09 |
| Q2 2025 | $54.4m | $4.8m | 0.09 |
| Q3 2025 | $36.7m | $6.4m | 0.18 |
| Q4 2025 | $67.0m | $9.8m | 0.15 |
Biggest buyers
| CITADEL ADVISORS LLC | Added | +2.0m |
| Driehaus Capital Management LLC | New | +1.6m |
| MORGAN STANLEY | Added | +1.3m |
| Assenagon Asset Management S.A. | New | +1.2m |
| First Light Asset Management, LLC | New | +1.1m |
| BNP PARIBAS FINANCIAL MARKETS | Added | +1.0m |
| MARSHALL WACE, LLP | New | +875.5k |
| JENNISON ASSOCIATES LLC | Added | +601.3k |
| VANGUARD GROUP INC | Added | +278.0k |
| Lisanti Capital Growth, LLC | New | +262.9k |
Biggest sellers
| Hood River Capital Management LLC | Sold out | -2.6m |
| UBS Group AG | Reduced | -1.1m |
| BlackRock, Inc. | Reduced | -952.3k |
| ArrowMark Colorado Holdings LLC | Reduced | -801.5k |
| Connor, Clark & Lunn Investment Management Ltd. | Sold out | -615.2k |
| ACADIAN ASSET MANAGEMENT LLC | Reduced | -526.0k |
| ROYAL BANK OF CANADA | Reduced | -472.6k |
| Walleye Capital LLC | Sold out | -463.4k |
| Freestone Grove Partners LP | Reduced | -427.5k |
| Trexquant Investment LP | Reduced | -395.0k |
Biggest calls
| UBS Group AG | Unchanged | $60.3m2.7m shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $2.6m117.5k shares |
| IMC-Chicago, LLC | Added | $960.5k43.7k shares |
| Walleye Capital LLC | Reduced | $648.4k29.5k shares |
| CITADEL ADVISORS LLC | Reduced | $624.2k28.4k shares |
| JANE STREET GROUP, LLC | New | $472.6k21.5k shares |
| Walleye Trading LLC | Added | $367.1k16.7k shares |
| SIMPLEX TRADING, LLC | Reduced | $358.3k16.3k shares |
| HRT FINANCIAL LP | Added | $331.0k15.1k shares |
| TUDOR INVESTMENT CORP ET AL | Reduced | $230.8k10.5k shares |
Biggest puts
| GROUP ONE TRADING LLC | Reduced | $2.6m118.0k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | $2.2m102.2k shares |
| D. E. Shaw & Co., Inc. | Unchanged | $1.5m70.0k shares |
| JANE STREET GROUP, LLC | Added | $1.2m55.7k shares |
| CITADEL ADVISORS LLC | Reduced | $769.3k35.0k shares |
| Walleye Trading LLC | Reduced | $422.0k19.2k shares |
| Walleye Capital LLC | Reduced | $404.4k18.4k shares |
| IMC-Chicago, LLC | New | $283.5k12.9k shares |
| TUDOR INVESTMENT CORP ET AL | Reduced | $226.4k10.3k shares |
| SIMPLEX TRADING, LLC | Reduced | $120.9k5.5k shares |
Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
| BlackRock, Inc. 13G · institution filed 2025-04-29 | 15.2% |
| Sessa Capital (Master), L.P. 13G · passive investor new · filed 2025-05-15 | 6.7% |
| VANGUARD PORTFOLIO MANAGEMENT LLC 13G · institution new · filed 2026-04-29 | 5.9% |
| VANGUARD CAPITAL MANAGEMENT LLC 13G · institution new · filed 2026-04-30 | 5.2% |
Fell to 5% or below in the last year: Voya Financial, Inc. (0.2%, 2026-08-06), VANGUARD GROUP INC (0.0%, 2026-03-27; now reported by VANGUARD PORTFOLIO MANAGEMENT LLC), ArrowMark Colorado Holdings LLC (4.3%, 2026-02-17)
Insider purchases and sales in Q4 2025
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q1 2024 | 0 | — | 0 | — | — |
| Q2 2024 | 0 | — | 1 | $258.4k | — |
| Q3 2024 | 0 | — | 0 | — | — |
| Q4 2024 | 1 | $12.4k | 1 | $1.2m | — |
| Q1 2025 | 1 | $190.9k | 0 | — | — |
| Q2 2025 | 0 | — | 0 | — | — |
| Q3 2025 | 2 | $251.7k | 0 | — | — |
| Q4 2025 | 0 | — | 0 | — | — |
None reported in Q4 2025.
Holders, Q4 2025
| Manager | Shares | Change |
|---|---|---|
| BlackRock, Inc. 0.00% of their portfolio | 11.1m $245.1m | Reduced -952.3k |
| VANGUARD GROUP INC 0.00% of their portfolio | 7.3m $161.4m | Added +278.0k |
| Sessa Capital IM, L.P. 2.18% of their portfolio | 5.0m $109.9m | Unchanged |
| ArrowMark Colorado Holdings LLC 1.40% of their portfolio | 2.9m $63.5m | Reduced -801.5k |
| GW&K Investment Management, LLC 0.51% of their portfolio | 2.7m $58.8m | Reduced -46.5k |
| STATE STREET CORP 0.00% of their portfolio | 2.6m $58.1m | Reduced -26.5k |
| CITADEL ADVISORS LLC 0.03% of their portfolio | 2.1m $45.9m | Added +2.0m |
| MORGAN STANLEY 0.00% of their portfolio | 2.1m $45.7m | Added +1.3m |
| Paradice Investment Management LLC 8.89% of their portfolio | 2.1m $45.7m | Reduced -118.7k |
| JENNISON ASSOCIATES LLC 0.03% of their portfolio | 2.0m $44.4m | Added +601.3k |
| GOLDMAN SACHS GROUP INC 0.01% of their portfolio | 1.7m $37.0m | Added +252.0k |
| JACOBS LEVY EQUITY MANAGEMENT, INC 0.14% of their portfolio | 1.7m $36.3m | Added +171.8k |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 1.6m $36.3m | Added +51.1k |
| Driehaus Capital Management LLC 0.24% of their portfolio | 1.6m $35.4m | New |
| Freestone Grove Partners LP 0.23% of their portfolio | 1.4m $31.7m | Reduced -427.5k |
| BNP PARIBAS FINANCIAL MARKETS 0.02% of their portfolio | 1.2m $27.4m | Added +1.0m |
| Assenagon Asset Management S.A. 0.04% of their portfolio | 1.2m $27.0m | New |
| TWO SIGMA INVESTMENTS, LP 0.04% of their portfolio | 1.2m $26.4m | Added +84.3k |
| BAILLIE GIFFORD & CO 0.02% of their portfolio | 1.1m $25.2m | Added +24.9k |
| First Light Asset Management, LLC 1.83% of their portfolio | 1.1m $23.9m | New |
| TWO SIGMA ADVISERS, LP 0.04% of their portfolio | 938.0k $20.6m | Reduced -32.9k |
| BARCLAYS PLC 0.01% of their portfolio | 917.9k $20.2m | Reduced -272.2k |
| MARSHALL WACE, LLP 0.02% of their portfolio | 875.5k $19.2m | New |
| D. E. Shaw & Co., Inc. 0.01% of their portfolio | 854.3k $18.8m | Reduced -23.0k |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 702.5k $15.4m | Added +44.1k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 691.7k $15.2m | Added +810 |
| FMR LLC 0.00% of their portfolio | 672.6k $14.8m | Reduced -197.5k |
| ROYCE & ASSOCIATES LP 0.14% of their portfolio | 650.2k $14.3m | Added +140.2k |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 646.3k $14.2m | Added +87.9k |
| MILLENNIUM MANAGEMENT LLC 0.01% of their portfolio | 583.6k $12.8m | Reduced -122.3k |
| Nuveen, LLC 0.00% of their portfolio | 563.3k $12.4m | Added +60.7k |
| Aberdeen Group plc 0.02% of their portfolio | 547.0k $12.0m | Reduced -51.1k |
| UBS Group AG 0.00% of their portfolio | 417.8k $9.2m | Reduced -1.1m |
| FRONTIER CAPITAL MANAGEMENT CO LLC 0.10% of their portfolio | 412.3k $9.1m | Reduced -3.1k |
| ACADIAN ASSET MANAGEMENT LLC 0.01% of their portfolio | 392.8k $8.6m | Reduced -526.0k |
| DAFNA Capital Management LLC 1.81% of their portfolio | 355.2k $7.8m | Unchanged |
| Bank of New York Mellon Corp 0.00% of their portfolio | 349.8k $7.7m | Reduced -34.4k |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 341.6k $7.5m | Reduced -376.5k |
| AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 339.6k $7.5m | Reduced -75.6k |
| PRINCIPAL FINANCIAL GROUP INC 0.00% of their portfolio | 324.3k $7.1m | Reduced -2.4k |
| VOYA INVESTMENT MANAGEMENT LLC 0.01% of their portfolio | 319.5k $7.0m | Added +145.4k |
| Quantinno Capital Management LP 0.01% of their portfolio | 292.5k $6.4m | Added +91.7k |
| Invesco Ltd. 0.00% of their portfolio | 277.7k $6.1m | Reduced -24.3k |
| SECTOR GAMMA AS 1.34% of their portfolio | 267.1k $5.9m | Reduced -2.5k |
| Lisanti Capital Growth, LLC 1.37% of their portfolio | 262.9k $5.8m | New |
| Balyasny Asset Management L.P. 0.01% of their portfolio | 262.8k $5.8m | New |
| EDMOND DE ROTHSCHILD HOLDING S.A. 0.08% of their portfolio | 258.2k $5.7m | Reduced -75.0k |
| Public Sector Pension Investment Board 0.02% of their portfolio | 234.7k $5.2m | Reduced -28.9k |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 234.3k $5.1m | Added +10.6k |
| ENVESTNET ASSET MANAGEMENT INC 0.00% of their portfolio | 221.7k $4.9m | Reduced -14.7k |
| JANE STREET GROUP, LLC 0.01% of their portfolio | 210.0k $4.6m | Reduced -7.3k |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 208.5k $4.6m | Reduced -472.6k |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 184.2k $4.0m | Reduced -6.0k |
| ADAGE CAPITAL PARTNERS GP, L.L.C. 0.01% of their portfolio | 183.0k $4.0m | New |
| CANADA PENSION PLAN INVESTMENT BOARD 0.00% of their portfolio | 177.6k $3.9m | Unchanged |
| Legal & General Group Plc 0.00% of their portfolio | 171.9k $3.8m | Reduced -10.6k |
| HRT FINANCIAL LP 0.01% of their portfolio | 170.5k $3.7m | Added +81.7k |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 0.00% of their portfolio | 164.9k $3.6m | Reduced -20.0k |
| PANAGORA ASSET MANAGEMENT INC 0.01% of their portfolio | 146.2k $3.2m | Reduced -49.0k |
| MIZUHO MARKETS AMERICAS LLC 0.07% of their portfolio | 144.6k $3.2m | Added +27.3k |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP 0.00% of their portfolio | 135.8k $3.0m | New |
| Swiss National Bank 0.00% of their portfolio | 133.3k $2.9m | Added +4.2k |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.00% of their portfolio | 130.3k $2.9m | Reduced -44.8k |
| AMERIPRISE FINANCIAL INC 0.00% of their portfolio | 128.7k $2.8m | Reduced -40.0k |
| Russell Investments Group, Ltd. 0.00% of their portfolio | 128.7k $2.8m | Reduced -9.0k |
| RAYMOND JAMES FINANCIAL INC 0.00% of their portfolio | 120.2k $2.6m | Reduced -16.8k |
| PDT Partners, LLC 0.16% of their portfolio | 110.4k $2.4m | Reduced -60.0k |
| ALGERT GLOBAL LLC 0.04% of their portfolio | 108.9k $2.4m | Reduced -117.9k |
| TUDOR INVESTMENT CORP ET AL 0.01% of their portfolio | 108.1k $2.4m | New |
| SEI INVESTMENTS CO 0.00% of their portfolio | 106.6k $2.3m | Reduced -109.4k |
| Trexquant Investment LP 0.02% of their portfolio | 102.7k $2.3m | Reduced -395.0k |
| WELLINGTON MANAGEMENT GROUP LLP 0.00% of their portfolio | 98.3k $2.2m | New |
| BANQUE PICTET & CIE SA 0.02% of their portfolio | 97.2k $2.1m | Added +22.2k |
| Universal- Beteiligungs- und Servicegesellschaft mbH 0.00% of their portfolio | 89.1k $2.0m | Reduced -9.2k |
| Engineers Gate Manager LP 0.02% of their portfolio | 88.5k $1.9m | New |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 84.4k $1.9m | Added +32.2k |
| Y-Intercept (Hong Kong) Ltd 0.04% of their portfolio | 84.0k $1.8m | Added +27.1k |
| Cerity Partners LLC 0.00% of their portfolio | 76.8k $1.7m | Added +472 |
| Zurcher Kantonalbank (Zurich Cantonalbank) 0.00% of their portfolio | 74.0k $1.6m | Added +52.6k |
| HSBC HOLDINGS PLC 0.00% of their portfolio | 73.1k $1.6m | Reduced -19.8k |
| Legato Capital Management LLC 0.14% of their portfolio | 72.6k $1.6m | New |
| FORMULA GROWTH LTD 0.60% of their portfolio | 70.9k $1.6m | Reduced -51.2k |
| NEW YORK STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 68.3k $1.5m | Unchanged |
| Susquehanna Portfolio Strategies, LLC 0.02% of their portfolio | 66.5k $1.5m | Reduced -139.6k |
| PRUDENTIAL FINANCIAL INC 0.00% of their portfolio | 65.0k $1.4m | Reduced -4.4k |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 64.4k $1.4m | Added +3.8k |
| RICE HALL JAMES & ASSOCIATES, LLC 0.08% of their portfolio | 62.4k $1.4m | Reduced -40.2k |
| SG Americas Securities, LLC 0.00% of their portfolio | 62.0k $1.4m | Reduced -1.1k |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.00% of their portfolio | 61.4k $1.4m | Reduced -1.3k |
| GROUP ONE TRADING LLC 0.04% of their portfolio | 60.7k $1.3m | Reduced -24.0k |
| NATIXIS ADVISORS, LLC 0.00% of their portfolio | 57.0k $1.3m | Added +617 |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 56.8k $1.2m | Reduced -9.0k |
| CANADA LIFE ASSURANCE Co 0.00% of their portfolio | 56.3k $1.2m | Unchanged |
| NORGES BANK 0.00% of their portfolio | 54.3k $1.2m | Not comparable |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 54.2k $1.2m | Reduced -536 |
| Thrivent Financial for Lutherans 0.00% of their portfolio | 46.6k $1.0m | Reduced -2.2k |
| Nierenberg Investment Management Company, LLC 0.49% of their portfolio | 44.6k $979.3k | New |
| WINTON GROUP Ltd 0.03% of their portfolio | 44.2k $972.5k | New |
| STATE OF WISCONSIN INVESTMENT BOARD 0.00% of their portfolio | 43.1k $947.1k | Reduced -21.6k |
| Jump Financial, LLC 0.01% of their portfolio | 41.4k $910.3k | Reduced -77.0k |