- Common stock, par value $0.0001 per share (the "Shares") (IMSR)

Q: What does CUSIP 881454102 represent in this 13F holders report?

CUSIP 881454102 is the security identifier for IMSR - Terrestrial Energy Inc. /DE/ - Common stock, par value $0.0001 per share (the "Shares") used to aggregate holder disclosures.

Q: How many institutions held IMSR - Terrestrial Energy Inc. /DE/ - Common stock, par value $0.0001 per share (the "Shares") in Q4 2025?

82 institutional investors reported IMSR - Terrestrial Energy Inc. /DE/ - Common stock, par value $0.0001 per share (the "Shares") for Q4 2025. Use the holders table for investor-level position and value details.

CUSIP: 881454102

Q4 2025 13F Holders as of 31 Dec 2025

Security type / class: Equity / Common stock, par value $0.0001 per share (the "Shares")
Total 13F shares: 21,415,986
Total 13F value: $130,661,482
Share change: +21,387,486
Put/Call ratio: 35%
SEC-reported price per share: $6.11
Number of holders: 82
Value change: +$130,487,347
Number of buys: 81
Shares outstanding: 104,718,000

Security key

881454102

Report period

Q4 2025

Institutions

Top holders

IMSR full security history Ownership snapshot Full 13F holder table Newer quarter: Q2 2026 Terrestrial Energy Inc. /DE/ SEC filings Terrestrial Energy Inc. /DE/ company facts

Broader feeds

Latest 13F filings Latest 13D/G filings Investors directory

Reporting periods

Holder history for CUSIP 881454102

Newer quarter: Q2 2026

Recent filing periods:

Q2 2026

Ownership snapshot

Top reported holders of IMSR - Terrestrial Energy Inc. /DE/ - Common stock, par value $0.0001 per share (the "Shares") (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

15/15

Latest evidence

31 Dec 2025

13D/G 3/4/5 13F Lead comparable stake: 14% 13D/G row: Roberto Marco Sella Showing 1-6 of 15 holder rows.

Quick read

Roberto Marco Sella leads the comparable SEC ownership view at 14%.

15 of 15 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 1-6 of 15 holder rows

Holder	Evidence	Ownership %	Position	12M Net Δ	As of
Roberto Marco Sella	13D/G 3/4/5 10%+ Owner 13D/G 3/4/5	14%	$93,974,555 15,378,689 shares	$0	29 Oct 2025
Simon Irish	3/4/5 13D/G Chief Executive Officer, Director 3/4/5 13D/G	13% from 13D/G	$98,684,142 5,333,007 shares mixed-class rows	—	28 Oct 2025
David Michael LeBlanc	13D/G David LeBlanc 13D/G	9.7%	— 11,400,410 shares	$0	28 Oct 2025
BARCLAYS PLC	13D/G 13D/G	6.2%	$15,368,295 1,420,360 shares	$0	31 Dec 2024
First Trust Capital Management L.P.	13D/G 13D/G	4.7%	$11,889,476 1,071,124 shares	-$7,523,891	30 Jun 2025
LMR Partners LLP	13F 13D/G Company 13F 13D/G	4.1% from 13D/G	$11,901,631 725,267 shares	—	30 Sep 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.

13F holder rows

Institutional holders as of Q4 2025

Investor-level positions for this CUSIP, loaded as an interactive table.

Institutions

21,415,986

Rows available

Investor	Option	Weight %	Change %	SEC-reported value	* Price	Shares	Share Change	Activity	Report Period

^* SEC-reported price is the security price as of the portfolio date and can indicate the last known price at which the security was still held. The marker flags a reported price that did not pass the local price check.

Compare Q4 2025 vs Q3 2025 Across Filers

Q3 2025 holders

Q4 2025 holders

Holder diff

Investor	Q3 2025 Shares	Q4 2025 Shares	Share Diff	Share Chg %	Q3 2025 value	Q4 2025 value	Value change	Value Chg %

Trend: ostatnie 8 kwartałów (+ wybrane okresy porównania).

Quarterly Holders Trend

Quarterly Value Trend

Quarterly Shares Trend