Atrium Therapeutics, Inc.

Overview

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• TickerRNA on Nasdaq¹
• IndustryPharmaceutical Preparations¹
• HeadquartersSan Diego, California¹
• Incorporated inDE²
• Business address3020 Callan Road, San Diego, Ca 92121²
• Filer category, Emerging growth company²

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Corporate structure

Atrium Therapeutics, Inc. is part of a group headed by Avidity Biosciences, Inc.. 3 entities, 2 countries on record. Switch between the flow chart and the network, and select any entity to see its details.

Built from subsidiaries listed in Exhibit 21 of annual reports filed with the SEC; major holders from Schedules 13D and 13G. Each entity in the chart links to its source.

Leadership

Who has led Atrium Therapeutics, Inc., and when. Pick a name to see everywhere that person has worked.

• Chief financial officerBrendan R. Winslow Feb 26, 2026 to now³

Timeline

1. Oct 9, 20268-K Other events¹³
2. Oct 8, 20268-K Entered a material agreement; Unregistered sale of shares; Other events¹⁴
3. Aug 13, 20268-K Results of operations¹⁵
4. Jul 14, 20268-K Other events¹⁶
5. May 14, 20268-K Results of operations¹⁷
6. Feb 27, 20268-K Entered a material agreement; Change in control; Executive or director change¹⁸
7. Feb 26, 20268-K Regulation FD disclosure¹⁹

Calendar

Coming up

1. Nov 12, 2026Reports results for the quarter ending Sep/2026²⁰

When it reported results

1. Aug 13, 2026Reported quarterly or annual results¹⁵
2. May 14, 2026Reported quarterly or annual results¹⁷

Upcoming dates from Nasdaq's calendar; past results from the company's 8-K filings (Item 2.02). The full markets calendar

Filings

53 filings to the SEC since October 2021: 2 quarterly reports, 7 major events, 30 insider forms, 7 large holders, 7 other. The latest 20:

1. Oct 9, 20268-K/A EDGAR
2. Oct 8, 20268-K EDGAR
3. Sep 22, 20264 EDGAR
4. Sep 22, 20264 EDGAR
5. Sep 22, 20264 EDGAR
6. Sep 22, 20264 EDGAR
7. Sep 22, 20264 EDGAR
8. Sep 22, 20264 EDGAR
9. Sep 22, 20264 EDGAR
10. Sep 22, 20264 EDGAR
11. Aug 14, 2026SCHEDULE 13G/A EDGAR
12. Aug 14, 2026SCHEDULE 13G EDGAR
13. Aug 14, 2026SCHEDULE 13G/A EDGAR
14. Aug 13, 202610-Q EDGAR
15. Aug 13, 20268-K EDGAR
16. Jul 27, 2026SCHEDULE 13G/A EDGAR
17. Jul 14, 20268-K EDGAR
18. May 15, 2026SCHEDULE 13G EDGAR
19. May 14, 202610-Q EDGAR
20. May 14, 20268-K EDGAR

Every filing from the last five years, summarized. The full record is on SEC EDGAR.

Major holders

Investors who own more than 5% of the shares must tell the SEC: a 13D if they may seek to influence the company, a 13G if they hold passively.

• PRICE T ROWE ASSOCIATES INC /MD/SCHEDULE 13G/A, 2 filings Apr 8, 2026 to Aug 14, 2026²¹
• RA CAPITAL MANAGEMENT, L.P.SCHEDULE 13G/A, 2 filings May 15, 2026 to Aug 14, 2026²²
• Sessa Capital IM, L.P.SCHEDULE 13G, 1 filing Aug 14, 2026²³
• BlackRockSCHEDULE 13G/A, 2 filings Apr 27, 2026 to Jul 27, 2026²⁴

SEC filer profile

How Atrium Therapeutics, Inc. is registered with the Securities and Exchange Commission, from its EDGAR record and the cover page of its latest annual report.

• Name on EDGARAtrium Therapeutics, Inc.¹
• CIK0002093101
• Filer status<br>emerging growth company¹
• Incorporated inDelaware¹
• Fiscal year endsDecember 31¹
• Industry code (SIC)2834 Pharmaceutical Preparations¹
• SEC reviewing officeOffice of Life Sciences, Division of Corporation Finance¹
• Business address3020 Callan Road, San Diego, CA 92121¹
• Phone858-401-7900¹
• Shares outstanding17,105,643 as of Aug 3, 2026²⁵
• On EDGAR sinceDec 10, 2025¹
• Filings53 in all: 4 (19), 3 (11), 8-K (6), SCHEDULE 13G (4), SCHEDULE 13G/A (3), 10-12B/A (2), 10-Q (2), S-8 (2)¹
  All 12 form types

  10-12B (1), 8-K/A (1), CERT (1), SEC STAFF ACTION (1)

• Latest filingsQuarterly report (10-Q) Aug 13, 2026
  Latest 8-K (8-K) Oct 8, 2026