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 ($2.3m 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 ≈ $12.14. Options: 11 managers hold calls ($36.7m notional), 11 hold puts ($6.4m).
Trends to Q3 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 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q4 2023 | 150 | 117 |
| 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 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q4 2024 | $113.7m | $7.4m | 0.06 |
| Q1 2025 | $61.6m | $5.5m | 0.09 |
| Q2 2025 | $54.4m | $4.8m | 0.09 |
| Q3 2025 | $36.7m | $6.4m | 0.18 |
Biggest buyers
| Freestone Grove Partners LP | New | +1.9m |
| BlackRock, Inc. | Added | +1.2m |
| ArrowMark Colorado Holdings LLC | Added | +991.6k |
| BARCLAYS PLC | Added | +623.1k |
| ACADIAN ASSET MANAGEMENT LLC | Added | +560.2k |
| D. E. Shaw & Co., Inc. | Added | +538.5k |
| ROYCE & ASSOCIATES LP | New | +510.0k |
| Cubist Systematic Strategies, LLC | New | +439.2k |
| Paradice Investment Management LLC | Added | +429.3k |
| AQR CAPITAL MANAGEMENT LLC | Added | +374.1k |
Biggest sellers
| Stephens Investment Management Group LLC | Sold out | -1.7m |
| Ophir Asset Management Pty Ltd | Sold out | -1.5m |
| Champlain Investment Partners, LLC | Sold out | -1.5m |
| BROWN ADVISORY INC | Sold out | -1.1m |
| Capital World Investors | Sold out | -767.0k |
| FRED ALGER MANAGEMENT, LLC | Sold out | -667.3k |
| MORGAN STANLEY | Reduced | -528.0k |
| GOLDMAN SACHS GROUP INC | Reduced | -455.1k |
| ROYAL BANK OF CANADA | Reduced | -418.0k |
| ExodusPoint Capital Management, LP | Sold out | -417.3k |
Biggest calls
| UBS Group AG | Unchanged | $33.3m2.7m shares |
| Walleye Capital LLC | Added | $840.1k69.2k shares |
| CITADEL ADVISORS LLC | Added | $546.3k45.0k shares |
| WOLVERINE TRADING, LLC | Added | $439.8k37.3k shares |
| IMC-Chicago, LLC | Added | $424.9k35.0k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | $298.6k24.6k shares |
| SIMPLEX TRADING, LLC | Added | $216.0k17.8k shares |
| Walleye Trading LLC | Reduced | $199.1k16.4k shares |
| TUDOR INVESTMENT CORP ET AL | New | $168.7k13.9k shares |
| HRT FINANCIAL LP | New | $167.0k13.8k shares |
Biggest puts
| GROUP ONE TRADING LLC | Added | $1.6m130.5k shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $1.4m115.1k shares |
| D. E. Shaw & Co., Inc. | New | $849.8k70.0k shares |
| CITADEL ADVISORS LLC | Added | $654.3k53.9k shares |
| JANE STREET GROUP, LLC | Unchanged | $542.7k44.7k shares |
| Walleye Capital LLC | Added | $537.8k44.3k shares |
| SIMPLEX TRADING, LLC | Added | $301.0k24.8k shares |
| Walleye Trading LLC | Added | $251.3k20.7k shares |
| TUDOR INVESTMENT CORP ET AL | New | $166.3k13.7k shares |
| WOLVERINE TRADING, LLC | Added | $154.4k13.1k 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 Q3 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 |
|---|---|---|---|---|---|
| Q4 2023 | 3 | $220.1k | 0 | — | — |
| 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 | — | — |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2025-08-11 | Sheridan John F PRESIDENT & CEO, director | Bought | $102.3k10.0k shares |
| 2025-08-08 | Vosseller Leigh EVP & CHIEF FINANCIAL OFFICER · Leigh A. Vosseller Trust | Bought | $149.4k13.7k shares |
Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).
Holders, Q3 2025
| Manager | Shares | Change |
|---|---|---|
| BlackRock, Inc. 0.00% of their portfolio | 12.1m $146.9m | Added +1.2m |
| VANGUARD GROUP INC 0.00% of their portfolio | 7.1m $85.7m | Reduced -306.5k |
| Sessa Capital IM, L.P. 1.53% of their portfolio | 5.0m $60.7m | Unchanged |
| ArrowMark Colorado Holdings LLC 0.83% of their portfolio | 3.7m $44.8m | Added +991.6k |
| GW&K Investment Management, LLC 0.29% of their portfolio | 2.7m $33.0m | Reduced -168.5k |
| STATE STREET CORP 0.00% of their portfolio | 2.7m $32.4m | Added +22.3k |
| Hood River Capital Management LLC 0.37% of their portfolio | 2.6m $31.0m | Reduced -13.3k |
| Paradice Investment Management LLC 5.98% of their portfolio | 2.2m $26.7m | Added +429.3k |
| Freestone Grove Partners LP 0.17% of their portfolio | 1.9m $22.7m | New |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 1.6m $19.4m | Reduced -8.1k |
| UBS Group AG 0.00% of their portfolio | 1.5m $18.3m | Added +120.4k |
| JACOBS LEVY EQUITY MANAGEMENT, INC 0.07% of their portfolio | 1.5m $18.0m | Added +50.6k |
| GOLDMAN SACHS GROUP INC 0.00% of their portfolio | 1.4m $17.4m | Reduced -455.1k |
| JENNISON ASSOCIATES LLC 0.01% of their portfolio | 1.4m $17.2m | Reduced -238.8k |
| BARCLAYS PLC 0.01% of their portfolio | 1.2m $14.4m | Added +623.1k |
| BAILLIE GIFFORD & CO 0.01% of their portfolio | 1.1m $13.6m | Reduced -5.1k |
| TWO SIGMA INVESTMENTS, LP 0.02% of their portfolio | 1.1m $13.6m | Reduced -115.5k |
| TWO SIGMA ADVISERS, LP 0.02% of their portfolio | 970.9k $11.8m | Added +82.8k |
| ACADIAN ASSET MANAGEMENT LLC 0.02% of their portfolio | 918.7k $11.1m | Added +560.2k |
| D. E. Shaw & Co., Inc. 0.01% of their portfolio | 877.2k $10.6m | Added +538.5k |
| FMR LLC 0.00% of their portfolio | 870.1k $10.6m | Added +345.4k |
| MORGAN STANLEY 0.00% of their portfolio | 737.5k $9.0m | Reduced -528.0k |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 718.1k $8.7m | Added +155.9k |
| MILLENNIUM MANAGEMENT LLC 0.01% of their portfolio | 705.9k $8.6m | Reduced -263.2k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 690.9k $8.4m | Reduced -9.5k |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 681.1k $8.3m | Reduced -418.0k |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 658.4k $8.0m | Added +112.8k |
| Connor, Clark & Lunn Investment Management Ltd. 0.02% of their portfolio | 615.2k $7.5m | Reduced -169.0k |
| Aberdeen Group plc 0.01% of their portfolio | 598.1k $7.3m | Added +241.9k |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 558.5k $6.8m | Reduced -58.5k |
| ROYCE & ASSOCIATES LP 0.06% of their portfolio | 510.0k $6.2m | New |
| Nuveen, LLC 0.00% of their portfolio | 502.6k $6.1m | Reduced -125.9k |
| Trexquant Investment LP 0.06% of their portfolio | 497.7k $6.0m | Added +129.2k |
| Walleye Capital LLC 0.05% of their portfolio | 463.4k $5.6m | Reduced -103.8k |
| Cubist Systematic Strategies, LLC 0.08% of their portfolio | 439.2k $5.3m | New |
| FRONTIER CAPITAL MANAGEMENT CO LLC 0.05% of their portfolio | 415.3k $5.0m | Added +51.2k |
| AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 415.1k $4.9m | Added +374.1k |
| Bank of New York Mellon Corp 0.00% of their portfolio | 384.1k $4.7m | Reduced -14.9k |
| BROWN CAPITAL MANAGEMENT LLC 0.18% of their portfolio | 363.4k $4.4m | Reduced -187.9k |
| DAFNA Capital Management LLC 1.07% of their portfolio | 355.2k $4.3m | Added +61.0k |
| EDMOND DE ROTHSCHILD HOLDING S.A. 0.06% of their portfolio | 333.2k $4.0m | Added +70.6k |
| PRINCIPAL FINANCIAL GROUP INC 0.00% of their portfolio | 326.7k $4.0m | Reduced -68.5k |
| Invesco Ltd. 0.00% of their portfolio | 302.0k $3.7m | Added +75.3k |
| SECTOR GAMMA AS 0.81% of their portfolio | 269.5k $3.3m | Added +59.0k |
| Public Sector Pension Investment Board 0.01% of their portfolio | 263.6k $3.2m | Added +36.5k |
| Kent Lake PR LLC 1.55% of their portfolio | 250.0k $3.0m | New |
| ENVESTNET ASSET MANAGEMENT INC 0.00% of their portfolio | 236.3k $2.9m | Reduced -41.7k |
| ALGERT GLOBAL LLC 0.05% of their portfolio | 226.9k $2.8m | Reduced -304.0k |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 223.7k $2.7m | Reduced -46.6k |
| MOORE CAPITAL MANAGEMENT, LP 0.05% of their portfolio | 220.5k $2.7m | Added +160.8k |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 219.6k $2.7m | Reduced -142.3k |
| JANE STREET GROUP, LLC 0.00% of their portfolio | 217.3k $2.6m | Added +127.2k |
| SEI INVESTMENTS CO 0.00% of their portfolio | 216.0k $2.6m | Added +29.3k |
| Susquehanna Portfolio Strategies, LLC 0.04% of their portfolio | 206.1k $2.5m | Reduced -40.9k |
| Quantinno Capital Management LP 0.01% of their portfolio | 200.8k $2.4m | Reduced -118.9k |
| PANAGORA ASSET MANAGEMENT INC 0.01% of their portfolio | 195.2k $2.4m | New |
| KBC Group NV 0.01% of their portfolio | 191.8k $2.3m | Unchanged |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 190.2k $2.3m | Reduced -3.0k |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 0.00% of their portfolio | 184.9k $2.2m | Reduced -84.0k |
| Legal & General Group Plc 0.00% of their portfolio | 182.4k $2.2m | Reduced -2.4k |
| CANADA PENSION PLAN INVESTMENT BOARD 0.00% of their portfolio | 177.6k $2.2m | New |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.00% of their portfolio | 175.1k $2.1m | Reduced -82.4k |
| Divisadero Street Capital Management, LP 0.10% of their portfolio | 174.7k $2.1m | Unchanged |
| VOYA INVESTMENT MANAGEMENT LLC 0.00% of their portfolio | 174.1k $2.1m | Added +36.4k |
| CAPITAL FUND MANAGEMENT S.A. 0.02% of their portfolio | 171.1k $2.1m | Reduced -91.3k |
| PDT Partners, LLC 0.13% of their portfolio | 170.4k $2.1m | Unchanged |
| AMERIPRISE FINANCIAL INC 0.00% of their portfolio | 168.7k $2.0m | Reduced -250.3k |
| RENAISSANCE TECHNOLOGIES LLC 0.00% of their portfolio | 161.5k $2.0m | Reduced -180.8k |
| Schonfeld Strategic Advisors LLC 0.01% of their portfolio | 142.9k $1.7m | Reduced -56.9k |
| Russell Investments Group, Ltd. 0.00% of their portfolio | 137.7k $1.7m | Reduced -61.0k |
| RAYMOND JAMES FINANCIAL INC 0.00% of their portfolio | 136.9k $1.7m | Reduced -6.3k |
| Swiss National Bank 0.00% of their portfolio | 129.1k $1.6m | Added +1.8k |
| Brevan Howard Capital Management LP 0.02% of their portfolio | 126.9k $1.5m | Added +32.2k |
| FORMULA GROWTH LTD 0.53% of their portfolio | 122.1k $1.5m | Unchanged |
| Jump Financial, LLC 0.02% of their portfolio | 118.4k $1.4m | Reduced -44.5k |
| MIZUHO MARKETS AMERICAS LLC 0.03% of their portfolio | 117.4k $1.4m | Reduced -21.4k |
| TRUIST FINANCIAL CORP 0.00% of their portfolio | 115.6k $1.4m | Reduced -8.0k |
| RICE HALL JAMES & ASSOCIATES, LLC 0.07% of their portfolio | 102.6k $1.2m | Reduced -1.4k |
| Summit Trail Advisors, LLC 0.02% of their portfolio | 101.3k $1.2m | Added +76.4k |
| GSA CAPITAL PARTNERS LLP 0.10% of their portfolio | 98.9k $1.2m | New |
| Universal- Beteiligungs- und Servicegesellschaft mbH 0.00% of their portfolio | 98.3k $1.2m | Reduced -3.0k |
| HSBC HOLDINGS PLC 0.00% of their portfolio | 92.9k $1.1m | Added +63.2k |
| HRT FINANCIAL LP 0.00% of their portfolio | 88.8k $1.1m | New |
| GROUP ONE TRADING LLC 0.03% of their portfolio | 84.8k $1.0m | Added +28.8k |
| Cerity Partners LLC 0.00% of their portfolio | 76.3k $926.3k | Reduced -6.0k |
| DARK FOREST CAPITAL MANAGEMENT LP 0.03% of their portfolio | 75.5k $917.0k | Added +14.5k |
| BANQUE PICTET & CIE SA 0.01% of their portfolio | 75.0k $910.3k | Reduced -9.0k |
| XTX Topco Ltd 0.05% of their portfolio | 73.5k $892.8k | Added +54.8k |
| INTECH INVESTMENT MANAGEMENT LLC 0.01% of their portfolio | 73.5k $892.2k | Added +26.1k |
| PRUDENTIAL FINANCIAL INC 0.00% of their portfolio | 69.4k $842.9k | Reduced -313.4k |
| NEW YORK STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 68.3k $829.0k | Unchanged |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 65.8k $799.0k | Added +6.6k |
| STATE OF WISCONSIN INVESTMENT BOARD 0.00% of their portfolio | 64.7k $785.2k | Reduced -95.9k |
| SG Americas Securities, LLC 0.00% of their portfolio | 63.1k $765.0k | Added +35.3k |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.00% of their portfolio | 62.7k $761.2k | Reduced -940 |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 60.6k $735.7k | Added +3 |
| Y-Intercept (Hong Kong) Ltd 0.02% of their portfolio | 56.9k $691.1k | New |
| NATIXIS ADVISORS, LLC 0.00% of their portfolio | 56.4k $685.0k | Added +14.0k |
| CANADA LIFE ASSURANCE Co 0.00% of their portfolio | 56.3k $664.0k | Unchanged |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 54.8k $664.9k | Added +6.4k |