Terrestrial Energy Inc.
IMSR- Exchange
- Nasdaq
- Industry
- Fabricated Plate Work (Boiler Shops)
- SEC CIK
- 0002019804
No open-market purchases or sales by Terrestrial Energy Inc. insiders were filed in the last 90 days; 110 institutions reported holding it in 13F filings for Q2 2026, worth $151.3M in total; no superinvestor holds it.
Other share classesIMSRW
Holders of 5% or more of IMSR
Holders whose latest Schedule 13D or 13G filing reports 5% or more of Terrestrial Energy Inc., largest stake first. The change is against the holder's previous filing.
| Holder | Latest form | Stake | Change | First filed | Latest filing | Filing |
|---|---|---|---|---|---|---|
| Sella Roberto Marco | 13G | 14.34%15.4M shares | New | Jan 22, 20261 filing | Jan 22, 2026 | SEC |
| Irish Simon | 13D | 12.80%13.6M shares | New | Nov 4, 20251 filing | Nov 4, 2025 | SEC |
| LeBlanc David Michael | 13D | 9.70%11.4M shares | New | Nov 4, 20251 filing | Nov 4, 2025 | SEC |
| Linden Capital L.P. | 13G | 8.70%2.00M shares | New | Mar 31, 20251 filing | Mar 31, 2025 | SEC |
| Picton Mahoney Asset Management | 13G | 8.61%1.98M shares | New | Oct 17, 20241 filing | Oct 17, 2024 | SEC |
| Barclays PLC | 13G/A | 6.17%1.42M shares | 0.00 ppfrom 6.17% | Feb 7, 20252 filings | Mar 21, 2025 | SEC |
| Magnetar Financial LLC | 13G/A | 6.07%1.40M shares | – | Aug 8, 20251 filing | Aug 8, 2025 | SEC |
| Citadel Advisors LLC | 13G | 5.40%1.23M shares | New | Sep 30, 20251 filing | Sep 30, 2025 | 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
24 Schedule 13D and 13G filings on Terrestrial Energy Inc., newest first, including old-format filings without a stake.
| Filed (ET) | Filer | Form | Stake | Change | Event date | Filing |
|---|---|---|---|---|---|---|
| Feb 17, 20264:53 PM ET | Citadel Advisors LLCand 6 others | 13G/A | 2.20%2.30M shares | –Below 5% | Dec 31, 2025 | SEC |
| Jan 22, 20265:16 PM ET | Sella Roberto Marcoand 2 others | 13G | 14.34%15.4M shares | New | Oct 29, 2025 | SEC |
| Nov 12, 202510:08 AM ET | Linden Capital L.P.and 3 others | 13G/A | 0.90%209.4K shares | –Below 5% | Sep 30, 2025 | SEC |
| Nov 12, 20258:13 AM ET | Magnetar Financial LLCand 3 others | 13G/A | 0.62%142.3K shares | –Below 5% | Sep 30, 2025 | SEC |
| Nov 4, 20254:35 PM ET | LeBlanc David Michael | 13D | 9.70%11.4M shares | New | Oct 28, 2025 | SEC |
| Nov 4, 20254:34 PM ET | Irish Simon | 13D | 12.80%13.6M shares | New | Oct 28, 2025 | SEC |
| Sep 30, 20255:34 PM ET | Citadel Advisors LLCand 6 others | 13G | 5.40%1.23M shares | New | Sep 23, 2025 | SEC |
| Aug 14, 20254:58 PM ET | Merus Global Investments, LLC | 13G/A | 3.80%866.1K shares | −2.60 ppfrom 6.40%Below 5% | Jun 30, 2025 | SEC |
| Aug 14, 20253:09 PM ET | Vivaldi Asset Management, LLCand 3 others | 13G/A | 4.66%1.07M shares | −2.94 ppfrom 7.60%Below 5% | Jun 30, 2025 | SEC |
| Aug 14, 20259:15 AM ET | LMR Partners LLPand 7 others | 13G/A | 4.10%941.3K shares | –Below 5% | Jun 30, 2025 | SEC |
| Aug 13, 20251:19 PM ET | AQR Capital Management LLCand 2 others | 13G/A | 0.01%1.45K shares | −5.59 ppfrom 5.60%Below 5% | Jun 30, 2025 | SEC |
| Aug 8, 20259:01 AM ET | Magnetar Financial LLCand 3 others | 13G/A | 6.07%1.40M shares | – | Jun 30, 2025 | SEC |
| Aug 6, 20255:01 PM ET | Picton Mahoney Asset Management | 13G/A | 4.10%942.1K shares | −4.51 ppfrom 8.61%Below 5% | Jun 30, 2025 | SEC |
| Jun 2, 20255:16 PM ET | Merus Global Investments, LLC | 13G | 6.40%1.48M shares | New | May 23, 2025 | SEC |
| May 15, 20256:54 PM ET | Vivaldi Asset Management, LLCand 3 others | 13G/A | 7.60%1.75M shares | – | Mar 31, 2025 | SEC |
| May 14, 202511:33 AM ET | AQR Capital Management LLCand 2 others | 13G/A | 5.60%1.29M shares | −1.20 ppfrom 6.80% | Mar 31, 2025 | SEC |
| May 12, 20252:20 PM ET | Goldman Sachs Group Incand 1 other | 13G/A | 3.20%746.4K shares | −2.00 ppfrom 5.20%Below 5% | Mar 31, 2025 | SEC |
| Mar 31, 202510:01 AM ET | Linden Capital L.P.and 3 others | 13G | 8.70%2.00M shares | New | Mar 26, 2025 | SEC |
| Mar 21, 20255:15 PM ET | Barclays PLC | 13G/A | 6.17%1.42M shares | 0.00 ppfrom 6.17% | Dec 31, 2024 | SEC |
| Feb 13, 20255:18 PM ET | AQR Capital Management LLCand 2 others | 13G/A | 6.80%1.56M shares | – | Dec 31, 2024 | SEC |
| Feb 12, 202511:38 AM ET | Goldman Sachs Group Incand 1 other | 13G | 5.20%1.19M shares | New | Dec 31, 2024 | SEC |
| Feb 11, 202512:57 PM ET | Picton Mahoney Asset Management | 13G/A | 8.61%1.98M shares | – | Dec 31, 2024 | SEC |
| Feb 7, 20254:15 PM ET | Barclays PLC | 13G | 6.17%1.42M shares | New | Dec 31, 2024 | SEC |
| Oct 17, 20243:14 PM ET | Picton Mahoney Asset Management | 13G | 8.61%1.98M shares | New | Sep 30, 2024 | SEC |
Form 144: proposed insider sales
Notices from officers, directors and other affiliates planning to sell Terrestrial Energy Inc. shares.
No Form 144 notices for Terrestrial Energy Inc. are on file.