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 ($3.8m this quarter). Holder counts are more reliable. Shares outstanding: 68.5m as of 2026-05-04, 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 ≈ $19.18. Options: 10 managers hold calls ($107.8m notional), 10 hold puts ($8.7m).
Trends to Q1 2026
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 |
| Q1 2026 | 274 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| 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 |
| Q1 2026 | 134 | 128 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q2 2025 | $54.4m | $4.8m | 0.09 |
| Q3 2025 | $36.7m | $6.4m | 0.18 |
| Q4 2025 | $67.0m | $9.8m | 0.15 |
| Q1 2026 | $107.8m | $8.7m | 0.08 |
Biggest buyers
| UBS Group AG | Added | +1.6m |
| WELLINGTON MANAGEMENT GROUP LLP | Added | +944.5k |
| Soleus Capital Management, L.P. | New | +783.0k |
| Defilade Capital Management, L.P. | New | +761.9k |
| Driehaus Capital Management LLC | Added | +694.1k |
| TWO SIGMA INVESTMENTS, LP | Added | +662.7k |
| ExodusPoint Capital Management, LP | New | +632.9k |
| MARSHALL WACE, LLP | Added | +566.9k |
| GOLDMAN SACHS GROUP INC | Added | +535.5k |
| VOYA INVESTMENT MANAGEMENT LLC | Added | +484.6k |
Biggest sellers
| Assenagon Asset Management S.A. | Reduced | -1.0m |
| BNP PARIBAS FINANCIAL MARKETS | Reduced | -1.0m |
| TWO SIGMA ADVISERS, LP | Sold out | -938.0k |
| MORGAN STANLEY | Reduced | -723.0k |
| BARCLAYS PLC | Reduced | -496.7k |
| BlackRock, Inc. | Reduced | -458.3k |
| JENNISON ASSOCIATES LLC | Reduced | -362.9k |
| BANK OF AMERICA CORP /DE/ | Reduced | -329.3k |
| Sessa Capital IM, L.P. | Reduced | -269.2k |
| Balyasny Asset Management L.P. | Sold out | -262.8k |
Biggest calls
| UBS Group AG | Added | $99.3m5.2m shares |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | $2.0m104.0k shares |
| BARCLAYS PLC | New | $1.7m90.6k shares |
| HRT FINANCIAL LP | Added | $1.6m83.7k shares |
| IMC-Chicago, LLC | Added | $1.1m55.9k shares |
| CITADEL ADVISORS LLC | Added | $897.2k46.8k shares |
| JANE STREET GROUP, LLC | Added | $665.2k34.7k shares |
| SIMPLEX TRADING, LLC | Reduced | $212.8k11.1k shares |
| Walleye Trading LLC | Reduced | $207.0k10.8k shares |
| GROUP ONE TRADING LLC | Added | $109.3k5.7k shares |
Biggest puts
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Added | $2.1m108.9k shares |
| Point72 Asset Management, L.P. | New | $1.7m90.0k shares |
| JANE STREET GROUP, LLC | Added | $1.4m70.9k shares |
| HRT FINANCIAL LP | New | $985.0k51.4k shares |
| BARCLAYS PLC | New | $801.3k41.8k shares |
| CITADEL ADVISORS LLC | Added | $722.7k37.7k shares |
| GROUP ONE TRADING LLC | Reduced | $521.4k27.2k shares |
| IMC-Chicago, LLC | Added | $396.8k20.7k shares |
| Walleye Trading LLC | Reduced | $69.0k3.6k shares |
| SIMPLEX TRADING, LLC | Reduced | $30.7k1.6k 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 Q1 2026
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 |
|---|---|---|---|---|---|
| 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 | — | — |
| Q1 2026 | 0 | — | 1 | $4.4k | $46 |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2026-03-17 | Novara Mark David EVP & CHIEF COMMERCIAL OFFICER | Sold | $4.3k187 shares |
| 2026-03-05 | Novara Mark David EVP & CHIEF COMMERCIAL OFFICER | Sold plan | $462 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, Q1 2026
| Manager | Shares | Change |
|---|---|---|
| BlackRock, Inc. 0.00% of their portfolio | 10.7m $204.9m | Reduced -458.3k |
| Sessa Capital IM, L.P. 1.73% of their portfolio | 4.7m $90.7m | Reduced -269.2k |
| VANGUARD PORTFOLIO MANAGEMENT LLC 0.00% of their portfolio | 4.0m $76.6m | First filing |
| ArrowMark Colorado Holdings LLC 1.58% of their portfolio | 3.1m $59.5m | Added +213.9k |
| VANGUARD CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 3.0m $58.3m | First filing |
| GW&K Investment Management, LLC 0.45% of their portfolio | 2.7m $51.5m | Added +13.9k |
| STATE STREET CORP 0.00% of their portfolio | 2.7m $51.0m | Added +20.5k |
| Driehaus Capital Management LLC 0.32% of their portfolio | 2.3m $44.2m | Added +694.1k |
| GOLDMAN SACHS GROUP INC 0.01% of their portfolio | 2.2m $42.5m | Added +535.5k |
| CITADEL ADVISORS LLC 0.03% of their portfolio | 2.2m $42.0m | Added +104.1k |
| UBS Group AG 0.01% of their portfolio | 2.0m $39.3m | Added +1.6m |
| Paradice Investment Management LLC 7.35% of their portfolio | 2.0m $39.2m | Reduced -35.3k |
| TWO SIGMA INVESTMENTS, LP 0.03% of their portfolio | 1.9m $35.7m | Added +662.7k |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 1.7m $32.2m | Added +30.5k |
| JENNISON ASSOCIATES LLC 0.02% of their portfolio | 1.7m $31.8m | Reduced -362.9k |
| JACOBS LEVY EQUITY MANAGEMENT, INC 0.12% of their portfolio | 1.5m $29.2m | Reduced -129.8k |
| MARSHALL WACE, LLP 0.03% of their portfolio | 1.4m $27.7m | Added +566.9k |
| MORGAN STANLEY 0.00% of their portfolio | 1.4m $26.0m | Reduced -723.0k |
| Freestone Grove Partners LP 0.18% of their portfolio | 1.3m $25.5m | Reduced -112.1k |
| First Light Asset Management, LLC 2.26% of their portfolio | 1.3m $25.2m | Added +225.2k |
| BAILLIE GIFFORD & CO 0.02% of their portfolio | 1.1m $20.9m | Reduced -56.1k |
| WELLINGTON MANAGEMENT GROUP LLP 0.00% of their portfolio | 1.0m $20.0m | Added +944.5k |
| VOYA INVESTMENT MANAGEMENT LLC 0.02% of their portfolio | 804.1k $15.4m | Added +484.6k |
| D. E. Shaw & Co., Inc. 0.01% of their portfolio | 783.9k $15.0m | Reduced -70.4k |
| Soleus Capital Management, L.P. 0.61% of their portfolio | 783.0k $15.0m | New |
| Defilade Capital Management, L.P. 2.05% of their portfolio | 761.9k $14.6m | New |
| MILLENNIUM MANAGEMENT LLC 0.01% of their portfolio | 761.7k $14.6m | Added +178.1k |
| FMR LLC 0.00% of their portfolio | 714.0k $13.7m | Added +41.4k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 706.6k $13.5m | Added +14.9k |
| ROYCE & ASSOCIATES LP 0.13% of their portfolio | 696.6k $13.4m | Added +46.3k |
| Quantinno Capital Management LP 0.02% of their portfolio | 653.9k $12.5m | Added +361.4k |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 642.6k $12.3m | Reduced -3.7k |
| ExodusPoint Capital Management, LP 0.12% of their portfolio | 632.9k $12.1m | New |
| Holocene Advisors, LP 0.02% of their portfolio | 477.4k $9.2m | Added +460.9k |
| VANGUARD FIDUCIARY TRUST CO 0.00% of their portfolio | 471.7k $9.0m | First filing |
| Aberdeen Group plc 0.01% of their portfolio | 434.0k $8.3m | Reduced -113.0k |
| BARCLAYS PLC 0.00% of their portfolio | 421.2k $8.1m | Reduced -496.7k |
| Point72 Asset Management, L.P. 0.01% of their portfolio | 420.5k $8.1m | New |
| FRONTIER CAPITAL MANAGEMENT CO LLC 0.08% of their portfolio | 397.2k $7.6m | Reduced -15.1k |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 373.2k $7.2m | Reduced -329.3k |
| Nuveen, LLC 0.00% of their portfolio | 363.8k $7.0m | Reduced -199.5k |
| DAFNA Capital Management LLC 1.55% of their portfolio | 355.2k $6.8m | Unchanged |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 349.8k $6.9m | Added +8.2k |
| FIRST TRUST ADVISORS LP 0.00% of their portfolio | 342.7k $6.6m | New |
| Bank of New York Mellon Corp 0.00% of their portfolio | 336.3k $6.4m | Reduced -13.5k |
| AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 331.9k $6.4m | Reduced -7.7k |
| PRINCIPAL FINANCIAL GROUP INC 0.00% of their portfolio | 331.5k $6.4m | Added +7.3k |
| Invesco Ltd. 0.00% of their portfolio | 294.1k $5.6m | Added +16.3k |
| ACADIAN ASSET MANAGEMENT LLC 0.01% of their portfolio | 278.1k $5.3m | Reduced -114.6k |
| SECTOR GAMMA AS 1.21% of their portfolio | 267.1k $5.1m | Unchanged |
| EDMOND DE ROTHSCHILD HOLDING S.A. 0.07% of their portfolio | 258.2k $4.9m | Unchanged |
| BEACONLIGHT CAPITAL, LLC 2.74% of their portfolio | 253.9k $4.9m | New |
| Trexquant Investment LP 0.03% of their portfolio | 249.3k $4.8m | Added +146.6k |
| ENVESTNET ASSET MANAGEMENT INC 0.00% of their portfolio | 243.2k $4.7m | Added +21.6k |
| Public Sector Pension Investment Board 0.01% of their portfolio | 242.6k $4.7m | Added +7.9k |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 208.7k $4.0m | Reduced -1.0m |
| Susquehanna Portfolio Strategies, LLC 0.06% of their portfolio | 206.2k $4.0m | Added +139.7k |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 206.0k $3.9m | Reduced -2.5k |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP 0.00% of their portfolio | 193.6k $3.7m | Added +57.8k |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 186.3k $3.6m | Added +2.1k |
| Assenagon Asset Management S.A. 0.01% of their portfolio | 178.6k $3.4m | Reduced -1.0m |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC 0.00% of their portfolio | 168.5k $3.2m | Added +3.6k |
| Lisanti Capital Growth, LLC 0.80% of their portfolio | 165.3k $3.2m | Reduced -97.6k |
| PANAGORA ASSET MANAGEMENT INC 0.01% of their portfolio | 163.7k $3.1m | Added +17.5k |
| MIZUHO MARKETS AMERICAS LLC 0.08% of their portfolio | 157.4k $3.0m | Added +12.7k |
| Legal & General Group Plc 0.00% of their portfolio | 155.3k $3.0m | Reduced -16.6k |
| TORONTO DOMINION BANK 0.01% of their portfolio | 150.1k $2.9m | New |
| Russell Investments Group, Ltd. 0.00% of their portfolio | 133.6k $2.6m | Added +4.9k |
| Swiss National Bank 0.00% of their portfolio | 133.3k $2.6m | Unchanged |
| RAYMOND JAMES FINANCIAL INC 0.00% of their portfolio | 125.3k $2.4m | Added +5.2k |
| BANQUE PICTET & CIE SA 0.03% of their portfolio | 123.9k $2.4m | Added +26.7k |
| FEDERATED HERMES, INC. 0.00% of their portfolio | 123.8k $2.4m | Added +123.8k |
| AMERIPRISE FINANCIAL INC 0.00% of their portfolio | 121.2k $2.3m | Reduced -7.6k |
| CANADA PENSION PLAN INVESTMENT BOARD 0.00% of their portfolio | 118.4k $2.3m | Reduced -59.2k |
| ALGERT GLOBAL LLC 0.03% of their portfolio | 117.8k $2.3m | Added +8.9k |
| INTECH INVESTMENT MANAGEMENT LLC 0.02% of their portfolio | 111.4k $2.1m | Added +84.0k |
| Verition Fund Management LLC 0.02% of their portfolio | 107.1k $2.1m | Added +96.5k |
| SEI INVESTMENTS CO 0.00% of their portfolio | 95.3k $1.8m | Reduced -11.3k |
| Zurcher Kantonalbank (Zurich Cantonalbank) 0.00% of their portfolio | 94.3k $1.8m | Added +20.3k |
| PDT Partners, LLC 0.11% of their portfolio | 93.8k $1.8m | Reduced -16.6k |
| Universal- Beteiligungs- und Servicegesellschaft mbH 0.00% of their portfolio | 87.4k $1.7m | Reduced -1.7k |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 84.3k $1.6m | Added +19.8k |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.00% of their portfolio | 80.7k $1.5m | Reduced -49.6k |
| Nierenberg Investment Management Company, LLC 0.76% of their portfolio | 79.5k $1.5m | Added +35.0k |
| TUDOR INVESTMENT CORP ET AL 0.01% of their portfolio | 79.0k $1.5m | Reduced -29.1k |
| Y-Intercept (Hong Kong) Ltd 0.03% of their portfolio | 77.9k $1.5m | Reduced -6.1k |
| Cerity Partners LLC 0.00% of their portfolio | 76.2k $1.5m | Reduced -543 |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 73.1k $1.6m | Reduced -161.1k |
| RICE HALL JAMES & ASSOCIATES, LLC 0.08% of their portfolio | 72.9k $1.4m | Added +10.5k |
| FORMULA GROWTH LTD 0.61% of their portfolio | 70.8k $1.4m | Reduced -91 |
| PRUDENTIAL FINANCIAL INC 0.00% of their portfolio | 69.4k $1.3m | Added +4.4k |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 68.7k $1.3m | Added +11.9k |
| CITIGROUP INC 0.00% of their portfolio | 68.3k $1.3m | Added +50.0k |
| NEW YORK STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 66.1k $1.3m | Reduced -2.2k |
| Cinctive Capital Management LP 0.08% of their portfolio | 63.8k $1.2m | New |
| NATIXIS ADVISORS, LLC 0.00% of their portfolio | 61.1k $1.2m | Added +4.1k |
| XTX Topco Ltd 0.02% of their portfolio | 60.8k $1.2m | New |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 60.6k $1.2m | Added +6.4k |
| JONES FINANCIAL COMPANIES LLLP 0.00% of their portfolio | 58.4k $1.2m | Added +56.8k |
| VANGUARD ASSET MANAGEMENT, Ltd 0.00% of their portfolio | 58.3k $1.1m | First filing |