Atrium Therapeutics, Inc.
RNA- Exchange
- Nasdaq
- Industry
- Pharmaceutical Preparations
- SEC CIK
- 0002093101
No open-market purchases or sales by Atrium Therapeutics, Inc. insiders were filed in the last 90 days; 154 institutions reported holding it in 13F filings for Q2 2026, worth $192.8M in total; no superinvestor holds it.
Holders of 5% or more of RNA
Holders whose latest Schedule 13D or 13G filing reports 5% or more of Atrium Therapeutics, Inc., largest stake first. The change is against the holder's previous filing.
| Holder | Latest form | Stake | Change | First filed | Latest filing | Filing |
|---|---|---|---|---|---|---|
| Sessa Capital IM, L.P. | 13G | 8.80%1.50M shares | New | Aug 14, 20261 filing | Aug 14, 2026 | SEC |
| Price T Rowe Associates Inc | 13G/A | 8.60%1.47M shares | −1.40 ppfrom 10.00% | Apr 8, 20262 filings | Aug 14, 2026 | SEC |
| BlackRock, Inc. | 13G/A | 6.60%1.14M shares | +1.40 ppfrom 5.20% | Apr 27, 20262 filings | Jul 27, 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 Atrium Therapeutics, Inc., newest first, including old-format filings without a stake.
| Filed (ET) | Filer | Form | Stake | Change | Event date | Filing |
|---|---|---|---|---|---|---|
| Aug 14, 20264:37 PM ET | Ra Capital Management, L.P.and 3 others | 13G/A | 0.00%0 shares | −5.60 ppfrom 5.60%Below 5% | Jun 30, 2026 | SEC |
| Aug 14, 20264:07 PM ET | Sessa Capital IM, L.P.and 1 other | 13G | 8.80%1.50M shares | New | Jun 30, 2026 | SEC |
| Aug 14, 202610:38 AM ET | Price T Rowe Associates Inc | 13G/A | 8.60%1.47M shares | −1.40 ppfrom 10.00% | Jun 30, 2026 | SEC |
| Jul 27, 20264:25 PM ET | BlackRock, Inc. | 13G/A | 6.60%1.14M shares | +1.40 ppfrom 5.20% | Jun 30, 2026 | SEC |
| May 15, 20264:32 PM ET | Ra Capital Management, L.P.and 3 others | 13G | 5.60%864.1K shares | New | Mar 31, 2026 | SEC |
| Apr 27, 20264:12 PM ET | BlackRock, Inc. | 13G | 5.20%892.4K shares | New | Mar 31, 2026 | SEC |
| Apr 8, 20263:25 PM ET | Price T Rowe Associates Inc | 13G | 10.00%1.55M shares | New | Mar 31, 2026 | SEC |
Form 144: proposed insider sales
Notices from officers, directors and other affiliates planning to sell Atrium Therapeutics, Inc. shares.
No Form 144 notices for Atrium Therapeutics, Inc. are on file.