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 Q3 2026

13F reference period

Q2 2026

Institutions Reporting

109

Shares (Excl. Options)

21.3MFull value: 21,296,870 · shares · 30 Jun 2026

Price

$7.08

The headline uses the Q2 2026 reference period after its reporting deadline. Available reports may still be incomplete or amended. Newer periods in the history table contain incoming reports and may be incomplete.

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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 30 Jun 2026
Q2 2026
Total 13F shares
21,296,870
Latest holder snapshot 5 signals
Total 13F value
$150,558,001
Portfolio coverage rank
0%
Share change
+2,915,828
Value change
+$21,242,721
Number of holders
109
Issuer context Names, identifiers, and filing context for this profile. 2 identity fields
Shares outstanding
104,718,000
SEC-reported price per share
$3.89
13F Shares, Excluding Options vs Price
13F Value, Excluding Options
Total Investors
Filing notes and source

Key facts

  • IMSR - Terrestrial Energy Inc. /DE/ - Common stock, par value $0.0001 per share (the "Shares") is tracked under CUSIP 881454102.
  • 109 institutions reported positions in Q2 2026.
  • 6 significant owners is listed from Schedule 13D/13G reporting.

Change

  • Holder count moved from 88 to 109 between Q1 2026 and Q2 2026.
  • SEC-reported value moved from
    $111.25MFull value: $111,253,410 · USD · 31 Mar 2026
    to
    $150.56MFull value: $150,558,001 · USD · 30 Jun 2026
    .

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

Latest holder context comes from 109 institutions filings for Q2 2026.

Open SEC evidence

Security key

881454102

13F reference period

Q2 2026

13F holders

109

13D/G owners

6

CIK / CUSIP context first

Open Q2 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

Latest 13F filings Latest 13D/G filings All securities

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 30 Jun 2026, 109 institutional investors reported holding
21.3MFull value: 21,296,870 · shares · 30 Jun 2026
shares of Terrestrial Energy Inc. /DE/ - Common stock, par value $0.0001 per share (the "Shares") (IMSR). This represents 20% of the company’s total
104.72MFull value: 104,718,000 · shares · Stored outstanding share count
outstanding shares.

13F concentration

Top 25 institutional shareholders

Largest 13F positions for this security by reported shares and value.

Top holder share
17%
Institution Ownership % Shares Held Share Change % Portfolio % Holdings Value
VANGUARD CAPITAL MANAGEMENT LLC 3.3% 3,414,196 +162% 0% $24,172,508
EXCHANGE TRADED CONCEPTS, LLC 2.1% 2,160,074 +3.3% 0.08% $15,293,324
UBS Group AG 1.7% 1,772,173 +259% 0% $12,546,985
HRT FINANCIAL LP 1.1% 1,125,849 0.01% $7,971,000
BlackRock, Inc. 1% 1,074,524 -4.1% 0% $7,607,630
JPMORGAN CHASE & CO 0.92% 966,797 -9.9% 0% $6,777,247
GEODE CAPITAL MANAGEMENT, LLC 0.66% 693,934 +5.2% 0% $4,915,460
LMR Partners LLP 0.66% 690,702 0% 0.04% $4,890,170
D. E. Shaw & Co., Inc. 0.64% 667,968 -45% 0% $4,729,214
Hudson Bay Capital Management LP 0.56% 589,293 +30% 0.02% $4,172,195
Pacer Advisors, Inc. 0.55% 574,618 0.01% $4,068,000
SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.55% 571,832 +73% 0% $4,048,571
WINTON GROUP Ltd 0.48% 504,000 +1.6% 0.12% $3,568,320
MORGAN STANLEY 0.39% 412,815 +45% 0% $2,922,730
Verition Fund Management LLC 0.36% 374,958 -16% 0.02% $2,654,703
VANGUARD FIDUCIARY TRUST CO 0.35% 365,772 +22% 0% $2,589,666
Vennlight Capital Management, LP 0.34% 353,010 -39% 1.7% $2,499,311
STATE STREET CORP 0.33% 346,696 +0.34% 0% $2,454,608
CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.32% 333,599 -1.3% 0% $2,361,881
HIGHBRIDGE CAPITAL MANAGEMENT LLC 0.23% 244,000 0.06% $1,710,440
JANE STREET GROUP, LLC 0.23% 240,719 0% $1,704,290
Alyeska Investment Group, L.P. 0.21% 222,000 -69% 0% $1,571,760
RENAISSANCE TECHNOLOGIES LLC 0.18% 183,800 -55% 0% $1,301,304
Creek Drive Management Group LLC 0.17% 175,000 -47% 0.77% $1,239,000
CastleKnight Management LP 0.16% 165,400 +172% 0.04% $1,171,032

Quarter history

Institutional holders across reporting periods

Holder count, reported shares/value, and median price by quarter.

Periods
4
Headline period
Q2 2026
Rows shown
1-4 of 4
Period 13F Shares, Excl. Options Value, Excl. Options Value Change Price (Median) Investors
2026 Q3 863,770 $3,359,842 -$6,270,984 $3.89 11
2026 Q2 21,296,870 $150,558,001 +$21,242,721 $7.08 109
2026 Q1 18,641,337 $111,253,410 -$12,847,821 $6.00 88
2025 Q4 21,415,986 $130,661,482 +$130,487,347 $6.11 82
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