Terrestrial Energy Inc.: 5%+ holders

As of November 6, 2026, 3 holders' latest Schedule 13D or 13G filings report owning 5% or more of Terrestrial Energy Inc. The largest reported stake is Roberto Marco Sella's, at 14.34%. 13 filings are on record since August 6, 2025 (Schedule 13G, January 22, 2026).

Who owns Terrestrial Energy Inc. /DE/?

Charles Pardee and 5 others are also named on 2 other Form D filings ↓

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Key facts

• Filed 2026-02-17 · Holder: Kenneth Griffin · Percent: 2.2% · SCHEDULE 13G/A
• Filed 2026-01-22 · Holder: Roberto Marco Sella · Percent: 14.34% · SCHEDULE 13G
• Filed 2025-11-12 · Holder: Magnetar Financial LLC · Percent: 0.62% · SCHEDULE 13G/A
• Filed 2025-11-12 · Holder: Linden Capital L.P. · Percent: 0.9% · SCHEDULE 13G/A
• Filed 2025-11-04 · Holder: Simon Irish · Percent: 12.8% · SCHEDULE 13D

Terrestrial Energy Inc. has 13 Schedule 13D or 13G filings on record since 2025-08-06. 3 holders' latest filing reports 5% or more of common stock, par value $0.0001 per share (the "shares"). Each figure below is the holder's own, as filed, with the filing linked.

Holders

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More on Terrestrial Energy Inc. and the records around it.

The people at Terrestrial Energy Inc.

• Charles Pardee, David Hill, David LeBlanc, Hugh MacDiarmid, Simon Irish and William Johnson are also named on 2 other Form D filings: Terrestrial Energy Inc. (Jul 2025)
• Brian Thrasher and Robert Jones are also named on 1 other Form D filing: Terrestrial Energy Inc. (Jul 2025)

Terrestrial Energy Inc. elsewhere on the record

• Leadership changes Jul 2026
• Form D filing Mar 2026
• Who owns it

Companies that share a holder

• Roberto Marco Sella also filed stake reports on 1 other company: OFFERPAD SOLUTIONS INC. (Oct 2025)
• Merus Global Investments, LLC also filed stake reports on 10 other companies: General Fusion Group Ltd. (Aug 2026), D. Boral ARC Acquisition I Corp. (Jun 2026), Bleichroeder Acquisition Corp. II (Jun 2026)
• Picton Mahoney Asset Management also filed stake reports on 20 other companies: Blue Water Acquisition Corp. III (Oct 2026), Launch One Acquisition Corp. (Oct 2026), Pono Capital Four, Inc. (Oct 2026)

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Purpose of Transaction (Item 4)

Simon Irish

The Reporting Person acquired the shares reported herein for investment purposes and to incentivize him in connection with his employment with the Issuer. To the extent required by Item 4, the information contained in Item 3 and Item 6 is incorporated herein by reference. The Reporting Person serves as Chief Executive Officer of the Issuer and as a member of the Issuer's Board of Directors and, in such capacities, may have influence over the corporate activities of the Issuer, including activities that may relate to items described in subparagraphs (a) through (j) of Item 4 of Schedule 13D. Subject to the that certain Lock-Up Agreement, as described in Item 6 of this Schedule 13D, and the Issuer's Insider Trading Policy (the "Insider Trading Policy"), the Reporting Person may from time to time buy or sell securities of the Issuer as appropriate for his personal circumstances. Except as described herein, the Reporting Person does not have any present plans or proposals that relate to or would result in any of the transactions described in subparagraphs (a) through (j) of Item 4 of Schedule 13D. However, the Reporting Person reserves the right to formulate in the future plans or proposals that may relate to or result in the transactions described in subparagraphs (a) through (j) of Item 4 of Schedule 13D. The Reporting Person may, from time to time, purchase additional securities of the Issuer either in the open market or in privately negotiated transactions, depending …The first part of Item 4 of the SCHEDULE 13D filed 2025-11-04; the filing has the rest

David LeBlanc

The Reporting Person acquired the shares reported herein for investment purposes and to incentivize him in connection with his employment with the Issuer. To the extent required by Item 4, the information contained in Item 3 and Item 6 is incorporated herein by reference. The Reporting Person serves as Chief Technology Officer of the Issuer and as a member of the Issuer's Board of Directors and, in such capacities, may have influence over the corporate activities of the Issuer, including activities that may relate to items described in subparagraphs (a) through (j) of Item 4 of Schedule 13D. Subject to the that certain Lock-Up Agreement, as described in Item 6 of this Schedule 13D, and the Issuer's Insider Trading Policy (the "Insider Trading Policy"), the Reporting Person may from time to time buy or sell securities of the Issuer as appropriate for his personal circumstances. Except as described herein, the Reporting Person does not have any present plans or proposals that relate to or would result in any of the transactions described in subparagraphs (a) through (j) of Item 4 of Schedule 13D. However, the Reporting Person reserves the right to formulate in the future plans or proposals that may relate to or result in the transactions described in subparagraphs (a) through (j) of Item 4 of Schedule 13D. The Reporting Person may, from time to time, purchase additional securities of the Issuer either in the open market or in privately negotiated transactions, depending …The first part of Item 4 of the SCHEDULE 13D filed 2025-11-04; the filing has the rest

Timeline

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Questions about who owns Terrestrial Energy Inc.

Who owns Terrestrial Energy Inc.?

On this page, 3 holders' latest ownership filings report 5% or more of Terrestrial Energy Inc.: Roberto Marco Sella (14.34%, Schedule 13G, filed 2026-01-22), Simon Irish (12.8%, Schedule 13D, filed 2025-11-04) and David LeBlanc (9.7%, Schedule 13D, filed 2025-11-04).

Who are the largest shareholders of Terrestrial Energy Inc.?

By the share each holder's latest filing reports, the largest holders of Terrestrial Energy Inc. on this page are Roberto Marco Sella (14.34%), Simon Irish (12.8%) and David LeBlanc (9.7%).

When did Roberto Marco Sella buy into Terrestrial Energy Inc.?

The filings give report dates, not purchase dates. The earliest filing from Roberto Marco Sella on this page is the Schedule 13G, filed 2026-01-22, reporting 14.34%.

Is this an audit or a full list?

Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 13 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.

Also on the record for Terrestrial Energy Inc.

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Where this comes from

Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.

Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.

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