Tandem Diabetes Care Inc
TNDM- Exchange
- Nasdaq
- Industry
- Surgical & Medical Instruments & Apparatus
- SEC CIK
- 0001438133
No open-market purchases or sales by Tandem Diabetes Care Inc insiders were filed in the last 90 days; 274 institutions reported holding it in 13F filings for Q2 2026, worth $1.19B in total; no superinvestor holds it.
Holders of 5% or more of TNDM
Holders whose latest Schedule 13D or 13G filing reports 5% or more of Tandem Diabetes Care Inc, largest stake first. The change is against the holder's previous filing.
| Holder | Latest form | Stake | Change | First filed | Latest filing | Filing |
|---|---|---|---|---|---|---|
| BlackRock, Inc. | 13G/A | 15.20%10.1M shares | – | Apr 29, 20251 filing | Apr 29, 2025 | SEC |
| Sessa Capital (Master), L.P. | 13G | 6.71%4.47M shares | New | May 15, 20251 filing | May 15, 2025 | SEC |
| Voya Financial, Inc. | 13G | 6.30%4.34M shares | New | May 5, 20261 filing | May 5, 2026 | SEC |
| Vanguard Capital Management LLC | 13G | 5.18%3.55M shares | New | Apr 30, 20261 filing | Apr 30, 2026 | SEC |
Stakes are as of each holder's latest filing. Holders whose last filing was in the old format (before December 18, 2024) have no stake on record and are not listed, and after an acquisition or delisting holders usually stop filing.
13D and 13G filings
7 Schedule 13D and 13G filings on Tandem Diabetes Care Inc, newest first, including old-format filings without a stake.
| Filed (ET) | Filer | Form | Stake | Change | Event date | Filing |
|---|---|---|---|---|---|---|
| May 5, 202610:48 AM ET | Voya Financial, Inc. | 13G | 6.30%4.34M shares | New | Mar 31, 2026 | SEC |
| Apr 30, 20262:07 PM ET | Vanguard Capital Management LLC | 13G | 5.18%3.55M shares | New | Mar 31, 2026 | SEC |
| Mar 27, 20261:18 PM ET | Vanguard Group Inc | 13G/A | 0.00%0 shares | –Below 5% | Mar 13, 2026 | SEC |
| Feb 17, 20264:37 PM ET | ArrowMark Colorado Holdings LLC | 13G/A | 4.26%2.89M shares | −1.20 ppfrom 5.46%Below 5% | Dec 31, 2025 | SEC |
| Nov 13, 20259:01 AM ET | ArrowMark Colorado Holdings LLC | 13G | 5.46%3.69M shares | New | Sep 30, 2025 | SEC |
| May 15, 20254:13 PM ET | Sessa Capital (Master), L.P.and 4 others | 13G | 6.71%4.47M shares | New | Mar 31, 2025 | SEC |
| Apr 29, 202512:19 PM ET | BlackRock, Inc. | 13G/A | 15.20%10.1M shares | – | Mar 31, 2025 | SEC |
Form 144: proposed insider sales
Notices from officers, directors and other affiliates planning to sell Tandem Diabetes Care Inc shares.
No Form 144 notices for Tandem Diabetes Care Inc are on file.