Comparable stake leader
Roberto Marco Sella
SEC ownership of Terrestrial Energy Inc. /DE/
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0002019804.
Disclosed value leader
Simon Irish
Comparable rows
50/50
Latest evidence
30 Jun 2026
- Public ticker
- IMSR, IMSRW on Nasdaq
- Parsed ownership sources
-
13D/G, 3/4/5, and 13F
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
Roberto Marco Sella
Ranking: Comparable ownership first, then disclosed value
- Comparable ownership rows
-
50 of 50
Meaning: Rows with safely comparable ownership %
- Latest 13D/G holder
-
Roberto Marco Sella
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
- 0002019804
- Issuer location
- Charlotte, NC
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 Terrestrial Energy Inc. /DE/ (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
Roberto Marco Sella
Disclosed value leader
Simon Irish
Comparable rows
50/50
Latest evidence
30 Jun 2026
13D/G
3/4/5
13F
Lead comparable stake: 14%
13D/G row: Roberto Marco Sella
Showing 1-8 of 50 holder rows.
Quick read
Roberto Marco Sella leads the comparable SEC ownership view at 14%.
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 Roberto Marco Sella's linked filing trail.
Comparable ownership
Top 5
Roberto Marco Sella
14%
Simon Irish
13%
David Michael LeBlanc
9.7%
BARCLAYS PLC
6.2%
First Trust Capital Management L.P.
4.7%
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 |
|---|---|---|---|---|---|
| Roberto Marco Sella |
13D/G
3/4/5
10%+ Owner
|
14%
|
$93,974,555
15,378,689 shares
|
$0 | 29 Oct 2025 |
| Simon Irish |
3/4/5
13D/G
Chief Executive Officer, Director
|
13%
from 13D/G
|
$98,684,142
5,333,007 shares
mixed-class rows
|
— | 28 Oct 2025 |
| David Michael LeBlanc |
3/4/5
13D/G
Chief Technology Officer, Director · David LeBlanc
|
9.7%
from 13D/G
|
$119,621
52,499 shares
mixed-class rows
|
— | 12 Apr 2026 |
| BARCLAYS PLC |
13D/G
13F
Company
|
6.2%
|
$15,368,295
1,420,360 shares
|
$0 | 31 Dec 2024 |
| First Trust Capital Management L.P. |
13D/G
|
4.7%
|
$11,889,476
1,071,124 shares
|
-$7,523,891 | 30 Jun 2025 |
| LMR Partners LLP |
13F
13D/G
Company
|
4.1%
from 13D/G
|
$15,863,036
3,937,112 shares
mixed-class rows
|
— | 30 Jun 2026 |
| PICTON MAHONEY ASSET MANAGEMENT |
13D/G
|
4.1%
|
$10,457,099
942,081 shares
|
-$11,520,901 | 30 Jun 2025 |
| MERUS GLOBAL INVESTMENTS, LLC |
13D/G
|
3.8%
|
$9,613,244
866,058 shares
|
-$6,816,621 | 30 Jun 2025 |
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 19 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 1-19 of 19 reporting-owner rows connected to Terrestrial Energy Inc. /DE/. Open a relationship link for the CIK-to-CIK filing trail.
Rows
19
Largest Forms 3/4/5 holder
Simon Irish
Net 12M change
$0
Latest report
29 Jul 2026
Recent insider transactions for Terrestrial Energy Inc. /DE/
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 |
|---|---|---|---|---|---|---|---|---|---|---|
| Pamela Beth Cowan | IMSR | Stock Option (Right to Buy) | Award | 299,401 | 299,401 | 29 Jul 2026 | Direct | |||
| Kathryn Ann McCarthy | IMSR | Restricted Stock Units | Award | 2,049 | 2,049 | 23 Jul 2026 | Direct | |||
| Steven M. Millsap | IMSR | Restricted Stock Units | Award | 49,917 | 49,917 | 12 Apr 2026 | Direct | |||
| Brian Patrick Thrasher | IMSR | Stock Option (Right to Buy) | Award | 58,236 | 58,236 | 12 Apr 2026 | Direct | |||
| Brian Patrick Thrasher | IMSR | Restricted Stock Units | Award | 49,917 | 49,917 | 12 Apr 2026 | Direct | |||
| William F. Smith | IMSR | Stock Option (Right to Buy) | Award | 32,787 | 32,787 | 12 Apr 2026 | Direct | |||
| David Michael LeBlanc | IMSR | Stock Option (Right to Buy) | Award | 32,787 | 32,787 | 12 Apr 2026 | Direct | |||
| William D. Johnson | HOND | Restricted Stock Units | Award | 17.5% | 1,029 | 6,894 | 18 Dec 2025 | Direct | ||
| Frederick W. Buckman | HOND | Resricted Stock Units | Award | 17.5% | 1,176 | 7,879 | 18 Dec 2025 | Direct | ||
| Frederick W. Buckman | HOND | Restricted Stock Units | Award | 6,703 | 6,703 | 18 Dec 2025 | Direct | |||
| Robert Wood Jones | HOND | Resricted Stock Units | Award | 17.5% | 1,029 | 6,894 | 18 Dec 2025 | Direct | ||
| Robert Wood Jones | HOND | Restricted Stock Units | Award | 5,865 | 5,865 | 18 Dec 2025 | Direct | |||
| David John Hill | HOND | Resricted Stock Units | Award | 17.5% | 588 | 3,940 | 18 Dec 2025 | Direct | ||
| David John Hill | HOND | Restricted Stock Units | Award | 3,352 | 3,352 | 18 Dec 2025 | Direct | |||
| Charles G. Pardee | HOND | Resricted Stock Units | Award | 17.6% | 882 | 5,909 | 18 Dec 2025 | Direct | ||
| Charles G. Pardee | HOND | Restricted Stock Units | Award | 5,027 | 5,027 | 18 Dec 2025 | Direct | |||
| John Hugh MacDiarmid | HOND | Resricted Stock Units | Award | 17.5% | 1,029 | 6,894 | 18 Dec 2025 | Direct | ||
| John Hugh MacDiarmid | HOND | Restricted Stock Units | Award | 5,865 | 5,865 | 18 Dec 2025 | Direct | |||
| Shawn Matthews | HOND | Restricted Stock Units | Award | 4,925 | 4,925 | 18 Dec 2025 | Direct | |||
| Shawn Matthews | HOND | Common Stock, par value $0.0001 per share | Other | -51.4% | -2,920,000 | 2,755,000 | 06 Nov 2025 | See Footnote | ||
| Shawn Matthews | HOND | Warrants | Other | -81.9% | -3,500,000 | 775,000 | 06 Nov 2025 | See Footnote | ||
| Michael J. Connor | HOND | Common Stock, par value $0.0001 per share | Other | 25,000 | 25,000 | 28 Oct 2025 | Direct | |||
| Andrew Scott Brenner | HOND | Common Stock, par value $0.0001 per share | Other | 25,000 | 25,000 | 28 Oct 2025 | Direct | |||
| Jacob Loveless | HOND | Common Stock, par value $0.0001 per share | Other | 25,000 | 25,000 | 28 Oct 2025 | Direct | |||
| Shawn Matthews | HOND | Common Stock, par value $0.0001 per share | Other | 533,514 | 533,514 | 28 Oct 2025 | Direct | |||
| Shawn Matthews | HOND | Common Stock, par value $0.0001 per share | Other | 5,675,000 | 5,675,000 | 28 Oct 2025 | See Footnote | |||
| Shawn Matthews | HOND | Warrants | Other | -81.4% | -5,542,599 | 1,267,599 | 28 Oct 2025 | See Footnote | ||
| Simon Irish | HOND | Restricted Stock Units | Award | 166,298 | 166,298 | 28 Oct 2025 | Direct |
* marks a reported price that did not pass the local price check.