Tandem Diabetes Care Inc has 7 Schedule 13D or 13G filings on record since 2025-11-13. 2 holders' latest filing reports 5% or more of common stock, par value $0.001 per share. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| Vanguard Portfolio Management | 5.91% | 4,052,274 | SCHEDULE 13G, 2026-04-29 | 2026-03-31 |
| Vanguard Capital Management | 5.18% | 3,553,772 | SCHEDULE 13G, 2026-04-30 | 2026-03-31 |
| ArrowMark Colorado Holdings, LLC | 4.26% | 2,889,691 | SCHEDULE 13G/A, 2026-02-17 | 2025-12-31 |
| Voya Financial, Inc. | 0.2% | 149,088 | SCHEDULE 13G/A, 2026-08-06 | 2026-06-30 |
| The Vanguard Group | 0% | 0 | SCHEDULE 13G/A, 2026-03-27 | 2026-03-13 |
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-11-13 | ArrowMark Colorado Holdings, LLC | 5.46% | SCHEDULE 13G |
| 2026-02-17 | ArrowMark Colorado Holdings, LLC | 4.26% | SCHEDULE 13G/A |
| 2026-03-27 | The Vanguard Group | 0% | SCHEDULE 13G/A |
| 2026-04-29 | Vanguard Portfolio Management | 5.91% | SCHEDULE 13G |
| 2026-04-30 | Vanguard Capital Management | 5.18% | SCHEDULE 13G |
| 2026-05-05 | Voya Financial, Inc. | 6.3% | SCHEDULE 13G |
| 2026-08-06 | Voya Financial, Inc. | 0.2% | SCHEDULE 13G/A |
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Where this comes from
Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.
Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.