Who owns Terrestrial Energy (IMSR)
Which tracked institutional funds hold IMSR, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See IMSR company fundamentals →
Ownership as of the 2026-Q2 13F filings (latest filed 2026-09-22). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
How the tape is positioned
30 tracked funds added or opened IMSR while 15 trimmed or exited it between 2026-Q1 and 2026-Q2 — the tape is split. When large holders disagree on a name, the funds moving first are sometimes ahead of the story.
A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.
Conviction spread
IMSR’s largest tracked holder by dollar value, VANGUARD CAPITAL MANAGEMENT LLC, sizes it at 0.0% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 0.0pp gap the other way — the median holder sizes IMSR more heavily than its largest holder by dollar value does.
Book-share is each fund’s reported value in IMSR divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.
Institutional & insider positioning
Between 2026-Q1 and 2026-Q2, across 117 tracked filers holding IMSR, 67 increased or opened the position and 52 reduced or closed it; over the same quarter, there were no open-market insider Form 4s.
This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.
New buyers & exits
Funds opening or closing a position in IMSR between the 2026-Q1 and 2026-Q2 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.
New buyers 6
- HIGHBRIDGE CAPITAL MANAGEMENT LLC$2M
- JANE STREET GROUP, LLC$2M
- XTX Topco Ltd$670K
- Aquatic Capital Management LLC$630K
- VOLORIDGE INVESTMENT MANAGEMENT, LLC$590K
- Engineers Gate Manager LP$583K
Full exits 2
- HITE Hedge Asset Management LLC$1M
- Harraden Circle Investments, LLC$733K
Largest adds
- VANGUARD CAPITAL MANAGEMENT LLC$16M
- UBS Group AG$10M
- LMR Partners LLP$3M
- EXCHANGE TRADED CONCEPTS, LLC$3M
- Hudson Bay Capital Management LP$2M
- SUSQUEHANNA INTERNATIONAL GROUP, LLP$2M
Largest trims
- MILLENNIUM MANAGEMENT LLC$404M
- CITADEL ADVISORS LLC$8M
- Alyeska Investment Group, L.P.$3M
- D. E. Shaw & Co., Inc.$3M
- GOLDMAN SACHS GROUP INC$2M
- RENAISSANCE TECHNOLOGIES LLC$1M
Institutional holders
One row per tracked fund, most shares held first (every row is from one quarter; reported value breaks ties). “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding.
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| VANGUARD CAPITAL MANAGEMENT LLC added | 3,414,196 | $24M | 14.6% | 2026-Q2 |
| LMR Partners LLP trimmed | 3,246,410 | $11M | 6.6% | 2026-Q2 |
| EXCHANGE TRADED CONCEPTS, LLC added | 2,160,074 | $15M | 9.3% | 2026-Q2 |
| UBS Group AG added | 1,772,173 | $13M | 7.6% | 2026-Q2 |
| Hudson Bay Capital Management LP trimmed | 1,296,174 | $4M | 2.7% | 2026-Q2 |
| PEAK6 LLC added | 1,236,146 | $4M | 2.5% | 2026-Q2 |
| CANTOR FITZGERALD, L. P. trimmed | 1,082,851 | $4M | 2.1% | 2026-Q2 |
| BlackRock, Inc. trimmed | 1,074,524 | $8M | 4.6% | 2026-Q2 |
| JPMORGAN CHASE & CO trimmed | 966,797 | $7M | 4.1% | 2026-Q2 |
| Caption Management, LLC | 865,372 | $3M | 1.8% | 2026-Q2 |
| ARISTEIA CAPITAL, L.L.C. added | 840,047 | $3M | 1.7% | 2026-Q2 |
| Magnetar Financial LLC trimmed | 723,000 | $2M | 1.5% | 2026-Q2 |
| GEODE CAPITAL MANAGEMENT, LLC added | 693,934 | $5M | 3.0% | 2026-Q2 |
| D. E. Shaw & Co., Inc. trimmed | 667,968 | $5M | 2.9% | 2026-Q2 |
| BOOTHBAY FUND MANAGEMENT, LLC added | 621,000 | $4M | 2.7% | 2026-Q2 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP added | 571,832 | $4M | 2.5% | 2026-Q2 |
| WINTON GROUP Ltd added | 504,000 | $4M | 2.2% | 2026-Q2 |
| MORGAN STANLEY added | 412,815 | $3M | 1.8% | 2026-Q2 |
| Verition Fund Management LLC trimmed | 374,958 | $3M | 1.6% | 2026-Q2 |
| VANGUARD FIDUCIARY TRUST CO added | 365,772 | $3M | 1.6% | 2026-Q2 |
| Vennlight Capital Management, LP trimmed | 353,010 | $2M | 1.5% | 2026-Q2 |
| STATE STREET CORP added | 346,696 | $2M | 1.5% | 2026-Q2 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC trimmed | 333,599 | $2M | 1.4% | 2026-Q2 |
| HIGHBRIDGE CAPITAL MANAGEMENT LLC | 244,000 | $2M | 1.0% | 2026-Q2 |
| JANE STREET GROUP, LLC trimmed | 240,719 | $2M | 1.0% | 2026-Q2 |
| Alyeska Investment Group, L.P. trimmed | 222,000 | $2M | 1.0% | 2026-Q2 |
| Linden Advisors LP | 194,560 | $648K | 0.4% | 2026-Q2 |
| RENAISSANCE TECHNOLOGIES LLC trimmed | 183,800 | $1M | 0.8% | 2026-Q2 |
| Creek Drive Management Group LLC trimmed | 175,000 | $1M | 0.8% | 2026-Q2 |
| Arosa Capital Management LP | 175,000 | $592K | 0.4% | 2026-Q2 |
| CastleKnight Management LP added | 165,400 | $1M | 0.7% | 2026-Q2 |
| Shay Capital LLC added | 134,539 | $953K | 0.6% | 2026-Q2 |
| NORTHERN TRUST CORP added | 126,539 | $896K | 0.5% | 2026-Q2 |
| Yorkville Advisors Global, LP | 122,000 | $864K | 0.5% | 2026-Q2 |
| Periscope Capital Inc. | 122,000 | $730K | 0.4% | 2026-Q2 |
| COMMONWEALTH EQUITY SERVICES, LLC added | 110,794 | $784K | 0.5% | 2026-Q2 |
| TORONTO DOMINION BANK trimmed | 110,000 | $779K | 0.5% | 2026-Q2 |
| MILLENNIUM MANAGEMENT LLC trimmed | 96,035 | $680K | 0.4% | 2026-Q2 |
| XTX Topco Ltd trimmed | 94,601 | $670K | 0.4% | 2026-Q2 |
| Mount Lucas Management LP added | 93,000 | $658K | 0.4% | 2026-Q2 |
| Aquatic Capital Management LLC new | 88,952 | $630K | 0.4% | 2026-Q2 |
| SONA ASSET MANAGEMENT (US) LLC | 85,566 | $606K | 0.4% | 2026-Q2 |
| Squarepoint Ops LLC trimmed | 85,500 | $605K | 0.4% | 2026-Q2 |
| VOLORIDGE INVESTMENT MANAGEMENT, LLC new | 83,374 | $590K | 0.4% | 2026-Q2 |
| Engineers Gate Manager LP added | 82,295 | $583K | 0.4% | 2026-Q2 |
| TIEMANN INVESTMENT ADVISORS, LLC | 75,995 | $538K | 0.3% | 2026-Q2 |
| MOORE CAPITAL MANAGEMENT, LP | 75,000 | $531K | 0.3% | 2026-Q2 |
| IMC-Chicago, LLC added | 74,991 | $531K | 0.3% | 2026-Q2 |
| Parallax Volatility Advisers, L.P. new | 68,518 | $485K | 0.3% | 2026-Q2 |
| Saba Capital Management, L.P. | 65,681 | $219K | 0.1% | 2026-Q2 |
| AQR CAPITAL MANAGEMENT LLC new | 59,777 | $423K | 0.3% | 2026-Q2 |
| GOLDMAN SACHS GROUP INC trimmed | 59,425 | $421K | 0.3% | 2026-Q2 |
| Swiss National Bank | 56,600 | $401K | 0.2% | 2026-Q2 |
| BALYASNY ASSET MANAGEMENT L.P. trimmed | 56,461 | $400K | 0.2% | 2026-Q2 |
| Walleye Capital LLC trimmed | 52,616 | $178K | 0.1% | 2026-Q2 |
| ALLSTATE CORP new | 50,205 | $355K | 0.2% | 2026-Q2 |
| WOLVERINE ASSET MANAGEMENT LLC added | 50,067 | $169K | 0.1% | 2026-Q2 |
| Alberta Investment Management Corp | 50,000 | $169K | 0.1% | 2026-Q2 |
| MMCAP International Inc. SPC | 44,279 | $313K | 0.2% | 2026-Q2 |
| LPL Financial LLC added | 42,381 | $300K | 0.2% | 2026-Q2 |
| TUDOR INVESTMENT CORP ET AL added | 42,225 | $299K | 0.2% | 2026-Q2 |
| ExodusPoint Capital Management, LP new | 40,205 | $285K | 0.2% | 2026-Q2 |
| SIMON QUICK ADVISORS, LLC | 40,000 | $283K | 0.2% | 2026-Q2 |
| Y-Intercept (Hong Kong) Ltd new | 38,150 | $270K | 0.2% | 2026-Q2 |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM | 31,276 | $221K | 0.1% | 2026-Q2 |
| CANADA PENSION PLAN INVESTMENT BOARD new | 29,000 | $205K | 0.1% | 2026-Q2 |
| AMERICAN CENTURY COMPANIES INC new | 26,768 | $190K | 0.1% | 2026-Q2 |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC trimmed | 26,399 | $187K | 0.1% | 2026-Q2 |
| BANK OF AMERICA CORP /DE/ trimmed | 25,431 | $180K | 0.1% | 2026-Q2 |
| PRELUDE CAPITAL MANAGEMENT, LLC added | 25,000 | $177K | 0.1% | 2026-Q2 |
| Advisory Services Network, LLC added | 24,555 | $174K | 0.1% | 2026-Q2 |
| DRW Securities, LLC | 22,000 | $156K | 0.1% | 2026-Q2 |
| Legal & General Group Plc added | 21,537 | $152K | 0.1% | 2026-Q2 |
| SLT Holdings LLC new | 21,000 | $149K | 0.1% | 2026-Q2 |
| Foundations Investment Advisors, LLC new | 21,000 | $149K | 0.1% | 2026-Q2 |
| FLAX POND CAPITAL, LLC added | 21,000 | $126K | 0.1% | 2026-Q2 |
| MARSHALL WACE, LLP trimmed | 20,278 | $144K | 0.1% | 2026-Q2 |
| Vanguard Global Advisers, LLC trimmed | 19,963 | $141K | 0.1% | 2026-Q2 |
| VANGUARD ASSET MANAGEMENT, Ltd | 19,453 | $138K | 0.1% | 2026-Q2 |
| JONES FINANCIAL COMPANIES LLLP added | 17,382 | $117K | 0.1% | 2026-Q2 |
| Zurcher Kantonalbank (Zurich Cantonalbank) new | 17,093 | $121K | 0.1% | 2026-Q2 |
| Bank of New York Mellon Corp trimmed | 16,911 | $120K | 0.1% | 2026-Q2 |
| BANK OF MONTREAL /CAN/ added | 16,469 | $117K | 0.1% | 2026-Q2 |
| Valeo Financial Advisors, LLC new | 15,000 | $106K | 0.1% | 2026-Q2 |
| Stoic Point Capital Management LLC | 13,402 | $45K | 0.0% | 2026-Q2 |
| US BANCORP \DE\ new | 11,655 | $39K | 0.0% | 2026-Q2 |
| DNB Asset Management AS new | 11,430 | $81K | 0.0% | 2026-Q2 |
| Vanguard Investments Australia, Ltd. | 10,674 | $76K | 0.0% | 2026-Q2 |
| CITADEL ADVISORS LLC trimmed | 10,061 | $71K | 0.0% | 2026-Q2 |
| Cornerstone Advisory, LLC new | 10,003 | $71K | 0.0% | 2026-Q2 |
| INSIGNEO ADVISORY SERVICES, LLC | 10,000 | $71K | 0.0% | 2026-Q2 |
| FIRST FOUNDATION ADVISORS | 10,000 | $71K | 0.0% | 2026-Q2 |
| Clear Street Group Inc. | 10,000 | $34K | 0.0% | 2026-Q2 |
| Rockefeller Capital Management L.P. added | 7,000 | $50K | 0.0% | 2026-Q2 |
| Federation des caisses Desjardins du Quebec added | 6,450 | $46K | 0.0% | 2026-Q2 |
| KLP KAPITALFORVALTNING AS | 6,300 | $45K | 0.0% | 2026-Q2 |
| ROYAL BANK OF CANADA trimmed | 3,333 | $24K | 0.0% | 2026-Q2 |
| OSAIC HOLDINGS, INC. added | 2,737 | $19K | 0.0% | 2026-Q2 |
| NATIONAL BANK OF CANADA /FI/ trimmed | 1,999 | $14K | 0.0% | 2026-Q2 |
| CITIGROUP INC trimmed | 1,510 | $11K | 0.0% | 2026-Q2 |
Ownership over time
Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.
Reading this table
Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.
About 13F filings
A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.