Latest Period
Q1 2026
Security Snapshot
Terrestrial Energy Inc. /DE/ - Common stock, par value $0.0001 per share (the "Shares") (IMSR) Institutional Ownership
CUSIP: 881454102
13F Institutional Holders and Ownership History from Q4 2025 to Q1 2026
Institutions Reporting
88
Shares (Excl. Options)
18,641,337
Price
$6.00
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- Security type / class
- Equity / Common stock, par value $0.0001 per share (the "Shares")
- Symbol
- IMSR on Nasdaq
- All holders as of 31 Mar 2026
- Q1 2026
- Total 13F shares
- 18,641,337
- Total 13F value
- $111,253,410
- Portfolio coverage rank
- 0%
- Share change
- -2,085,873
- Value change
- -$12,845,554
- Number of holders
- 88
- Shares outstanding
- 104,718,000
- SEC-reported price per share
- $7.12
Latest holder snapshot
5 signals
Issuer context
Names, identifiers, and filing context for this profile.
2 identity fields
13F Shares, Excluding Options vs Price
13F Value, Excluding Options
Total Investors
Key facts
- IMSR - Terrestrial Energy Inc. /DE/ - Common stock, par value $0.0001 per share (the "Shares") is tracked under CUSIP 881454102.
- 88 institutions reported positions in Q1 2026.
- 6 significant owners is listed from Schedule 13D/13G reporting.
Change
- Holder count moved from 82 to 88 between Q4 2025 and Q1 2026.
- SEC-reported value moved from $130,661,482 to $111,253,410.
Research use
- You can quickly see who holds this security, then open quarter and manager detail pages for full evidence.
- 13F and Schedule 13D/13G sections are kept together so you can cross-check institutional and beneficial ownership context.
Evidence
Source: SEC Form 13F
Open SEC evidence
Latest holder context comes from 88 institutions filings for Q1 2026.
Security key
881454102
Latest holder period
Q1 2026
13F holders
88
13D/G owners
6
CIK / CUSIP context first
Open Q1 2026 holders
IMSR full holder history
Terrestrial Energy Inc. /DE/ SEC filings
Terrestrial Energy Inc. /DE/ company facts
Terrestrial Energy Inc. /DE/ insider transactions
Broader feeds
Recent Quarterly Holder Reports
Open recent reporting periods for CUSIP 881454102:
13D/G owners
Significant owners
Large-stake holder rows connected to Schedule 13D/G evidence.
Rows
6
Security
IMSR
| Filer | Ownership | Change % | Holdings Value | Net Change | Nb Shares | Change % | Reporting Name | Report Period |
|---|---|---|---|---|---|---|---|---|
| Sella Roberto Marco | 14% | $93,974,555 | 15,378,689 | Roberto Marco Sella | 29 Oct 2025 | |||
| Irish Simon | 13% | 13,586,445 | Simon Irish | 28 Oct 2025 | ||||
| LeBlanc David Michael | 9.7% | 11,400,410 | David LeBlanc | 28 Oct 2025 | ||||
| CITADEL ADVISORS LLC | 2.2% | $24,811,883 | 2,303,796 | Kenneth Griffin | 31 Dec 2025 | |||
| Linden Capital L.P. | 0.9% | 209,426 | Linden Capital L.P. | 30 Sep 2025 | ||||
| Magnetar Financial LLC | 0.62% | 142,304 | MAGNETAR FINANCIAL LLC | 30 Sep 2025 |
As of 31 Mar 2026, 88 institutional investors reported holding 18,641,337 shares of Terrestrial Energy Inc. /DE/ - Common stock, par value $0.0001 per share (the "Shares") (IMSR). This represents 18% of the company’s total 104,718,000 outstanding shares.
13F concentration
Top 25 institutional shareholders
Largest 13F positions for this security by reported shares and value.
Top holder share
15%
| Institution | Ownership % | Shares Held | Share Change % | Portfolio % | Holdings Value |
|---|---|---|---|---|---|
| EXCHANGE TRADED CONCEPTS, LLC | 2% | 2,091,161 | 0.1% | $12,557,422 | |
| VANGUARD CAPITAL MANAGEMENT LLC | 1.2% | 1,303,452 | 0% | 0% | $7,827,229 |
| CITADEL ADVISORS LLC | 1.2% | 1,277,258 | -37% | 0.01% | $7,669,934 |
| D. E. Shaw & Co., Inc. | 1.2% | 1,214,777 | +13% | 0.01% | $7,294,736 |
| BlackRock, Inc. | 1.1% | 1,120,885 | +2.6% | 0% | $6,730,914 |
| JPMORGAN CHASE & CO | 1% | 1,073,073 | -8.3% | 0% | $5,934,094 |
| Alyeska Investment Group, L.P. | 0.69% | 722,000 | 0% | 0.01% | $4,308,650 |
| LMR Partners LLP | 0.66% | 690,702 | +17% | 0.04% | $4,147,666 |
| GEODE CAPITAL MANAGEMENT, LLC | 0.63% | 659,388 | -17% | 0% | $3,962,170 |
| Vennlight Capital Management, LP | 0.55% | 575,499 | 3.5% | $3,455,872 | |
| WINTON GROUP Ltd | 0.47% | 496,300 | -23% | 0.1% | $2,980,282 |
| UBS Group AG | 0.47% | 493,577 | -3.7% | 0% | $2,963,930 |
| Hudson Bay Capital Management LP | 0.43% | 452,287 | -39% | 0.02% | $2,715,984 |
| Verition Fund Management LLC | 0.42% | 444,958 | -41% | 0.03% | $2,671,973 |
| RENAISSANCE TECHNOLOGIES LLC | 0.39% | 407,900 | +136% | 0% | $2,449,440 |
| GOLDMAN SACHS GROUP INC | 0.38% | 396,238 | +41% | 0% | $2,379,409 |
| STATE STREET CORP | 0.33% | 345,520 | +5.8% | 0% | $2,074,848 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC | 0.32% | 337,991 | -18% | 0% | $2,029,636 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | 0.32% | 330,276 | -5.2% | 0% | $1,983,307 |
| Creek Drive Management Group LLC | 0.32% | 330,000 | 1.2% | $1,981,650 | |
| VANGUARD FIDUCIARY TRUST CO | 0.29% | 300,407 | 0% | 0% | $1,803,944 |
| MORGAN STANLEY | 0.27% | 285,549 | +133% | 0% | $1,714,722 |
| Magnetar Financial LLC | 0.23% | 244,000 | +881% | 0.01% | $1,465,220 |
| HITE Hedge Asset Management LLC | 0.23% | 240,113 | 0.08% | $1,441,879 | |
| TORONTO DOMINION BANK | 0.22% | 225,974 | +804% | 0% | $1,356,974 |
Quarter history
Institutional holders across reporting periods
Holder count, reported shares/value, and median price by quarter.
Periods
2
Latest
Q1 2026
Rows shown
1-2 of 2