Comparable stake leader
Sessa Capital IM, L.P.
SEC ownership of Atrium Therapeutics, Inc.
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0002093101.
Disclosed value leader
Sessa Capital IM, L.P.
Comparable rows
50/50
Latest evidence
30 Jun 2026
- Public ticker
- RNA on Nasdaq
- Parsed ownership sources
-
13F and 13D/G
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
Sessa Capital IM, L.P.
Ranking: Comparable ownership first, then disclosed value
- Comparable ownership rows
-
50 of 50
Meaning: Rows with safely comparable ownership %
- Latest 13D/G holder
-
Sessa Capital IM, L.P.
Source: Latest parsed Schedule 13D/G stake
- Latest parsed ownership date
-
30 Jun 2026
Freshness: Most recent filing date in this holder set
- Issuer CIK
- 0002093101
- Issuer location
- San Diego, CA
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
3 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of Atrium Therapeutics, Inc. (13F + 13D/G + 3/4/5)
Grouped by holder across the latest SEC ownership disclosures. Start with comparable ownership when available, then verify the linked 13F, 13D/G, or 3/4/5 evidence.
Comparable stake leader
Sessa Capital IM, L.P.
Disclosed value leader
Sessa Capital IM, L.P.
Comparable rows
50/50
Latest evidence
30 Jun 2026
13F
13D/G
Lead comparable stake: 8.8%
13D/G row: Sessa Capital IM, L.P.
Showing 1-8 of 50 holder rows.
Quick read
Sessa Capital IM, L.P. leads the comparable SEC ownership view at 8.8%.
50 of 50 rows have a safely comparable ownership percentage. Use this as a filing-backed starting point, then open the detailed table for source links, reporting role, position value, share count, and filing date.
Open SEC evidence
Opens Sessa Capital IM, L.P.'s linked filing trail.
Comparable ownership
Top 5
Sessa Capital IM, L.P.
8.8%
PRICE T ROWE ASSOCIATES INC /MD/
8.6%
BlackRock, Inc.
6.6%
VANGUARD CAPITAL MANAGEMENT LLC
4.3%
CRCM LP
3.4%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 50 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| Sessa Capital IM, L.P. |
13F
13D/G
Company
|
8.8%
from 13D/G
|
$20,175,000
1,500,000 shares
|
— | 30 Jun 2026 |
| PRICE T ROWE ASSOCIATES INC /MD/ |
13F
13D/G
Company · T. Rowe Price Associates, Inc.
|
8.6%
from 13D/G
|
$19,813,000
1,472,984 shares
|
— | 30 Jun 2026 |
| BlackRock, Inc. |
13F
13D/G
Company
|
6.6%
from 13D/G
|
$19,468,551
1,447,476 shares
|
— | 30 Jun 2026 |
| VANGUARD CAPITAL MANAGEMENT LLC |
13F
Company
|
4.3%
|
$9,829,677
730,831 shares
|
— | 30 Jun 2026 |
| CRCM LP |
13F
Company
|
3.4%
|
$7,844,780
583,255 shares
|
— | 30 Jun 2026 |
| TIG Advisors, LLC |
13F
Company
|
3.3%
|
$7,552,619
561,533 shares
|
— | 30 Jun 2026 |
| GEODE CAPITAL MANAGEMENT, LLC |
13F
Company
|
2.3%
|
$5,205,392
386,929 shares
|
— | 30 Jun 2026 |
| TWO SIGMA INVESTMENTS, LP |
13F
Company
|
2%
|
$4,646,719
345,481 shares
|
— | 30 Jun 2026 |
How to read this table
Rows are grouped by holder and ranked first by SEC-reported ownership % when it is safely comparable, then by disclosed holdings value. — indicates unavailable or non-comparable values; "mixed-class rows" means the latest filing spans non-comparable classes.
Forms 3/4/5 flow
Insider trading overview
Insider buy and sell flow is broadly balanced over the last 12 months. No Buy or Sell transactions have been reported since 17 Aug 2025.
Buys
$0
Insiders: 0
Sells
$0
Insiders: 0
Net
$0
Shares: 0
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 0
Shares: 0
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 0 | $0 | $0 | $0 |
| 3-6 | 0 | 0 | $0 | $0 | $0 |
| 6-9 | 0 | 0 | $0 | $0 | $0 |
| 9-12 | 0 | 0 | $0 | $0 | $0 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-11 of 11 reporting-owner rows connected to Atrium Therapeutics, Inc.. Open a relationship link for the CIK-to-CIK filing trail.
Rows
11
Largest Forms 3/4/5 holder
Kathleen P. Gallagher
Net 12M change
$0
Latest report
20 Apr 2026
| Name | Relationship | Holdings Value | Past Year Net Change | Change % | Valuation | Report Date |
|---|---|---|---|---|---|---|
| Kathleen P. Gallagher | Chief Executive Officer and President, Director | $1,756,309 | Mixed | 20 Apr 2026 | ||
| Steven George Hughes | Chief Medical Officer | $977,314 | Mixed | 20 Apr 2026 | ||
| Husam Younis | Chief Scientific Officer | $704,029 | Mixed | 20 Apr 2026 | ||
| Rocio Martin Hoyos | Chief Strategy Officer | $623,848 | Mixed | 20 Apr 2026 | ||
| Brendan R. Winslow | Chief Financial Officer | $582,949 | Mixed | 20 Apr 2026 | ||
| Stephanie Kenney | Chief Corporate Affairs Officer | $474,103 | Mixed | 20 Apr 2026 | ||
| Sarah Boyce | Director | Mixed | 27 Feb 2026 | |||
| Carsten Boess | Director | Mixed | 27 Feb 2026 | |||
| Troy E. Wilson | Director | Mixed | 27 Feb 2026 | |||
| W. Michael Flanagan | Director | Mixed | 27 Feb 2026 | |||
| Simona Skerjanec | Director | Mixed | 27 Feb 2026 |
Recent insider transactions for Atrium Therapeutics, Inc.
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| Stephanie Kenney | RNA | Common Stock | Award | 549.4% | 30,000 | 35,460 | 20 Apr 2026 | Direct | ||
| Stephanie Kenney | RNA | Stock Option (Right to Buy) | Award | 60,000 | 60,000 | 20 Apr 2026 | Direct | |||
| Steven George Hughes | RNA | Common Stock | Award | 69.6% | 30,000 | 73,097 | 20 Apr 2026 | Direct | ||
| Steven George Hughes | RNA | Stock Option (Right to Buy) | Award | 60,000 | 60,000 | 20 Apr 2026 | Direct | |||
| Brendan R. Winslow | RNA | Common Stock | Award | 220.6% | 30,000 | 43,601 | 20 Apr 2026 | Direct | ||
| Brendan R. Winslow | RNA | Stock Option (Right to Buy) | Award | 60,000 | 60,000 | 20 Apr 2026 | Direct | |||
| Kathleen P. Gallagher | RNA | Common Stock | Award | 355.2% | 102,500 | 131,361 | 20 Apr 2026 | Direct | ||
| Kathleen P. Gallagher | RNA | Stock Option (Right to Buy) | Award | 205,000 | 205,000 | 20 Apr 2026 | Direct | |||
| Rocio Martin Hoyos | RNA | Common Stock | Award | 180.1% | 30,000 | 46,660 | 20 Apr 2026 | Direct | ||
| Rocio Martin Hoyos | RNA | Stock Option (Right to Buy) | Award | 60,000 | 60,000 | 20 Apr 2026 | Direct | |||
| Husam Younis | RNA | Common Stock | Award | 132.4% | 30,000 | 52,657 | 20 Apr 2026 | Direct | ||
| Husam Younis | RNA | Stock Option (Right to Buy) | Award | 60,000 | 60,000 | 20 Apr 2026 | Direct | |||
| Sarah Boyce | Stock Option (Right to Buy) | Award | 20,000 | 20,000 | 27 Feb 2026 | Direct | ||||
| Carsten Boess | Stock Option (Right to Buy) | Award | 20,000 | 20,000 | 27 Feb 2026 | Direct | ||||
| Troy Edward Wilson | Stock Option (Right to Buy) | Award | 20,000 | 20,000 | 27 Feb 2026 | Direct | ||||
| W. Michael Flanagan | Stock Option (Right to Buy) | Award | 20,000 | 20,000 | 27 Feb 2026 | Direct | ||||
| Simona Skerjanec | Stock Option (Right to Buy) | Award | 20,000 | 20,000 | 27 Feb 2026 | Direct |
* marks a reported price that did not pass the local price check.