Terrestrial Energy (IMSR)
Terrestrial Energy on one page: short interest, daily short volume, fails to deliver, large holders, 13F holders, earnings dates and insider trades. Listed on Nasdaq.
8.1M
Short interest
settlement 2026-10-15
4.7
Days to cover
+0.4 days vs prior
56.0%
Short share of volume
2026-11-02
377
Fails to deliver
settlement 2026-10-14
Mon 29 Mar
Next earnings
estimated date
3 people
Insiders buying, 30 days
$112K combined, latest 2026-10-14
$112K
Insider flow, 90 days
3 buys, 0 sells
As of 2026-11-02.
Short interest
FINRA, twice a month. The newest 24 settlements in the table, 24 in the chart. JSONAs of 15 October 2026, short interest in IMSR is 8,126,703 shares, up 2,323,016 shares over the last month. Over the last 24 readings it ranged from 1,224,234 shares (28 November 2025) to 8,126,703 shares (15 October 2026). The latest reading sits at the top of that range. At the reported average volume of 1.7M shares a day that is 4.7 days to cover.
Embed this chart.The embed keeps its attribution line.
<iframe src="https://xoomar.com/embed/stocks/imsr" width="100%" height="440" style="border:0;max-width:100%" loading="lazy" title="XOOMAR chart"></iframe>
| Settlement | Shares short | Change | Avg daily volume | Days to cover |
|---|---|---|---|---|
| 2026-10-15 | 8,126,703 | +26.1% | 1,747,643 | 4.65 |
| 2026-09-30 | 6,446,554 | +11.1% | 1,522,244 | 4.23 |
| 2026-09-15 | 5,803,687 | -11.8% | 1,303,562 | 4.45 |
| 2026-08-31 | 6,581,856 | +5.5% | 1,049,405 | 6.27 |
| 2026-08-14 | 6,239,551 | +7.1% | 1,340,889 | 4.65 |
| 2026-07-31 | 5,824,372 | +2.5% | 2,450,340 | 2.38 |
| 2026-07-15 | 5,683,558 | -4.9% | 1,831,490 | 3.10 |
| 2026-06-30 | 5,978,828 | +2.8% | 2,251,649 | 2.66 |
| 2026-06-15 | 5,814,557 | +21.7% | 3,302,874 | 1.76 |
| 2026-05-29 | 4,779,175 | +17.0% | 3,432,265 | 1.39 |
| 2026-05-15 | 4,083,931 | +18.6% | 3,440,150 | 1.19 |
| 2026-04-30 | 3,443,602 | +5.1% | 3,144,731 | 1.10 |
| 2026-04-15 | 3,276,068 | +0.6% | 1,517,700 | 2.16 |
| 2026-03-31 | 3,255,139 | -1.3% | 1,838,877 | 1.77 |
| 2026-03-13 | 3,296,337 | -10.6% | 1,172,633 | 2.81 |
| 2026-02-27 | 3,686,500 | -0.3% | 1,362,565 | 2.71 |
| 2026-02-13 | 3,697,779 | +19.7% | 2,018,053 | 1.83 |
| 2026-01-30 | 3,089,469 | -18.1% | 4,483,976 | 1.00 |
| 2026-01-15 | 3,770,596 | +24.7% | 5,828,510 | 1.00 |
| 2025-12-31 | 3,024,640 | +87.7% | 1,973,210 | 1.53 |
| 2025-12-15 | 1,611,109 | +31.6% | 1,488,282 | 1.08 |
| 2025-11-28 | 1,224,234 | -35.8% | 1,976,554 | 1.00 |
| 2025-11-14 | 1,906,165 | -25.5% | 1,782,811 | 1.07 |
| 2025-10-31 | 2,558,429 | +111.0% | 3,505,964 | 1.00 |
Daily short volume
FINRA Reg SHO, the last 30 sessions. JSONAs of 2 November 2026, the short share of IMSR volume is 56.0%, down 15.0 points over the last five sessions. Over the last 30 readings it ranged from 40.5% (9 October 2026) to 71.0% (26 October 2026). The latest reading is in line with the 30-session average of 57.3%, on 658K shares reported.
| Date | Short volume | Total volume | Short share | Exempt |
|---|---|---|---|---|
| 2026-11-02 | 368K | 658K | 56.0% | 53,932 |
| 2026-10-30 | 615K | 1.1M | 58.4% | 69,801 |
| 2026-10-29 | 623K | 999K | 62.3% | 45,156 |
| 2026-10-28 | 843K | 1.3M | 65.5% | 252,854 |
| 2026-10-27 | 912K | 1.7M | 52.3% | 13,043 |
| 2026-10-26 | 517K | 729K | 71.0% | 104 |
| 2026-10-23 | 263K | 468K | 56.2% | 21,222 |
| 2026-10-22 | 412K | 622K | 66.2% | 0 |
| 2026-10-21 | 482K | 840K | 57.5% | 3,102 |
| 2026-10-20 | 345K | 547K | 63.1% | 5,782 |
| 2026-10-19 | 317K | 510K | 62.2% | 278 |
| 2026-10-16 | 276K | 548K | 50.4% | 9 |
| 2026-10-15 | 670K | 1.2M | 57.6% | 4,974 |
| 2026-10-14 | 517K | 816K | 63.3% | 2,684 |
| 2026-10-13 | 774K | 1.2M | 63.5% | 74,393 |
| 2026-10-12 | 362K | 784K | 46.2% | 2,786 |
| 2026-10-09 | 369K | 911K | 40.5% | 2,985 |
| 2026-10-08 | 406K | 840K | 48.3% | 1,504 |
| 2026-10-07 | 350K | 601K | 58.3% | 1,010 |
| 2026-10-06 | 309K | 637K | 48.5% | 42 |
| 2026-10-05 | 248K | 517K | 47.9% | 82 |
| 2026-10-02 | 271K | 484K | 56.0% | 0 |
| 2026-10-01 | 384K | 721K | 53.2% | 528 |
| 2026-09-30 | 330K | 590K | 55.9% | 0 |
| 2026-09-29 | 507K | 758K | 66.9% | 75 |
| 2026-09-28 | 329K | 575K | 57.2% | 349 |
| 2026-09-25 | 240K | 371K | 64.6% | 59 |
| 2026-09-24 | 241K | 454K | 53.1% | 5,036 |
| 2026-09-23 | 198K | 366K | 54.1% | 1,698 |
| 2026-09-22 | 481K | 755K | 63.7% | 3,761 |
Fails to deliver
SEC, the last 30 settlement dates with a fail. JSONAs of 14 October 2026, the fails-to-deliver balance in IMSR is 377 shares, down 8,395 shares over the last settlement date. Over the last 30 readings it ranged from 304 shares (21 September 2026) to 101,825 shares (2 September 2026). The latest reading sits at the bottom of that range.
| Settlement | Shares failed | Price | Value |
|---|---|---|---|
| 2026-10-14 | 377 | $3.11 | $1K |
| 2026-10-13 | 8,772 | $2.96 | $26K |
| 2026-10-09 | 22,525 | $3.40 | $77K |
| 2026-10-06 | 7,914 | $3.75 | $30K |
| 2026-10-05 | 34,818 | $3.78 | $132K |
| 2026-10-02 | 53,293 | $3.83 | $204K |
| 2026-09-29 | 48,409 | $4.12 | $199K |
| 2026-09-28 | 12,169 | $4.31 | $52K |
| 2026-09-22 | 18,076 | $4.50 | $81K |
| 2026-09-21 | 304 | $4.16 | $1K |
| 2026-09-18 | 40,374 | $4.39 | $177K |
| 2026-09-17 | 33,910 | $4.25 | $144K |
| 2026-09-16 | 39,456 | $4.28 | $169K |
| 2026-09-11 | 3,232 | $5.26 | $17K |
| 2026-09-10 | 64,922 | $5.32 | $345K |
| 2026-09-09 | 2,687 | $5.67 | $15K |
| 2026-09-08 | 2,289 | $5.15 | $12K |
| 2026-09-04 | 7,635 | $5.08 | $39K |
| 2026-09-03 | 101,825 | $5.09 | $518K |
| 2026-09-02 | 101,825 | $4.98 | $507K |
| 2026-08-31 | 7,879 | $5.10 | $40K |
| 2026-08-28 | 969 | $5.49 | $5K |
| 2026-08-26 | 35,952 | $5.58 | $201K |
| 2026-08-25 | 8,268 | $5.19 | $43K |
| 2026-08-21 | 13,343 | $5.27 | $70K |
| 2026-08-20 | 7,028 | $5.69 | $40K |
| 2026-08-19 | 47,403 | $5.51 | $261K |
| 2026-08-18 | 62,891 | $5.82 | $366K |
| 2026-08-17 | 6,614 | $5.89 | $39K |
| 2026-08-14 | 31,689 | $6.06 | $192K |
Insider trades
SEC Form 4, newest first. JSONInsiders at IMSR reported 3 open-market buys worth $112K in the last 90 days and no open-market sells. Latest filing: Irish Simon (Chief Executive Officer) on 2026-10-28.
| Date | Insider | Title | Type | Shares | Price | Value | Owned after |
|---|---|---|---|---|---|---|---|
| 2026-10-28 | Irish Simon | Chief Executive Officer | Exercise or conversion | 55K | $0.00 | $0 | 2.9M |
| 2026-10-21 | Irish Simon | Chief Executive Officer | Exercise or conversion | 512K | $0.00 | $0 | 2.8M |
| 2026-10-14 | Pardee Charles G | Director | Buy | 8K | $2.95 | $22K | 14K |
| 2026-10-13 | Irish Simon | Chief Executive Officer | Buy | 17K | $3.01 | $51K | 2.3M |
| 2026-10-09 | BUCKMAN FREDERICK W | Director | Buy | 12K | $3.28 | $39K | 19K |
| 2025-11-06 | HCM Investor Holdings II, LLC | Other | Other transaction | 2.9M | price not stated in the filing | not stated | 2.8M |
| 2025-10-28 | Matthews Shawn | Director | Other transaction | 534K | price not stated in the filing | not stated | 534K |
| 2025-10-28 | Matthews Shawn | Director | Other transaction | 5.7M | price not stated in the filing | not stated | 5.7M |
| 2025-10-28 | Loveless Jacob | Other | Other transaction | 25K | price not stated in the filing | not stated | 25K |
| 2025-10-28 | Brenner Andrew Scott | Other | Other transaction | 25K | price not stated in the filing | not stated | 25K |
| 2025-10-28 | Connor Michael J | Other | Other transaction | 25K | price not stated in the filing | not stated | 25K |
Form 4 filings are due within two business days of the trade. Insiders sell for many reasons that say nothing about the company; open-market buys are rarer.
Large holders (13D and 13G)
One row per reporting person with its latest filing, newest first. JSON3 holders report 5% or more of IMSR in their latest filing, 2 on Schedule 13D (active intent). The largest reported stake is Roberto Marco Sella at 14.3% of the class (15,378,689 shares), filed 2026-01-22 for an event on 2025-10-29.
| Filed | Form | Holder | Shares | Of class | Event |
|---|---|---|---|---|---|
| 2026-02-17 | 13G/Ano. 1 | Kenneth Griffinparent holding company, individual | 2.3M | 2.2% | 2025-12-31 |
| 2026-02-17 | 13G/Ano. 1 | Citadel GP LLCparent holding company, other entity | 2.0M | 1.9% | 2025-12-31 |
| 2026-02-17 | 13G/Ano. 1 | Citadel Advisors Holdings LPparent holding company, partnership | 2.0M | 1.9% | 2025-12-31 |
| 2026-02-17 | 13G/Ano. 1 | Citadel Advisors LLCinvestment adviser, parent holding company, other entity | 2.0M | 1.9% | 2025-12-31 |
| 2026-02-17 | 13G/Ano. 1 | Citadel Securities GP LLCparent holding company, other entity | 275K | 0.3% | 2025-12-31 |
| 2026-02-17 | 13G/Ano. 1 | Citadel Securities LLCbroker-dealer, other entity | 275K | 0.3% | 2025-12-31 |
| 2026-02-17 | 13G/Ano. 1 | Citadel Securities Group LPparent holding company, partnership | 275K | 0.3% | 2025-12-31 |
| 2026-01-22 | 13G | Roberto Marco Sellaindividual | 15.4M | 14.3% | 2025-10-29 |
| 2026-01-22 | 13G | Roberto M. Sella 2012 Family Trustother entity | 1.5M | 1.4% | 2025-10-29 |
| 2026-01-22 | 13G | LL Charitable Foundationother entity | 653K | 0.6% | 2025-10-29 |
| 2025-11-12 | 13G/Ano. 1 | Siu Min Wongindividual, parent holding company | 209K | 0.9% | 2025-09-30 |
| 2025-11-12 | 13G/Ano. 1 | Linden Capital L.P.partnership | 209K | 0.9% | 2025-09-30 |
| 2025-11-12 | 13G/Ano. 1 | Linden GP LLCparent holding company | 209K | 0.9% | 2025-09-30 |
| 2025-11-12 | 13G/Ano. 1 | Linden Advisors LPinvestment adviser, partnership | 209K | 0.9% | 2025-09-30 |
| 2025-11-12 | 13G/Ano. 2 | MAGNETAR FINANCIAL LLCinvestment adviser, other entity | 142K | 0.6% | 2025-09-30 |
| 2025-11-12 | 13G/Ano. 2 | MAGNETAR CAPITAL PARTNERS LPparent holding company, partnership | 142K | 0.6% | 2025-09-30 |
| 2025-11-12 | 13G/Ano. 2 | SUPERNOVA MANAGEMENT LLCparent holding company, other entity | 142K | 0.6% | 2025-09-30 |
| 2025-11-12 | 13G/Ano. 2 | DAVID J. SNYDERMANparent holding company, individual | 142K | 0.6% | 2025-09-30 |
| 2025-11-04 | 13D | David LeBlancindividual | 11.4M | 9.7% | 2025-10-28 |
| 2025-11-04 | 13D | Simon Irishindividual | 13.6M | 12.8% | 2025-10-28 |
13F holders
Tracked managers holding IMSR at their latest 13F. JSON5 of the 30 tracked managers held IMSR at their latest 13F, $7.2M in total at quarter-end prices. D. E. Shaw & Co. is the largest at $4.7M (0.0% of its portfolio) as of 2026-06-30. Over the prior quarter 2 added shares and 3 cut.
| Fund | Quarter | Shares | Value | Of portfolio | Change in shares |
|---|---|---|---|---|---|
| D. E. Shaw & Co. | 2026-06-30 | 668K | $4.7M | 0.00% | -547K |
| Renaissance Technologies | 2026-06-30 | 184K | $1.3M | 0.00% | -224K |
| Millennium Management | 2026-06-30 | 96K | $680K | 0.00% | new |
| AQR Capital Management | 2026-06-30 | 60K | $423K | 0.00% | new |
| Citadel Advisors | 2026-06-30 | 10K | $71K | 0.00% | -1.3M |
Only the 30 tracked managers on the funds hub; a 13F reports long positions in US listed stock at quarter end, 45 days late, and says nothing about shorts or positions sold since.
What this page is
Terrestrial Energy in the regulatory record
Regulators publish company data in separate files that never sit next to each other: FINRA's twice-monthly short interest, its daily short sale volume, the SEC's fails-to-deliver counts, and each insider's Form 4. A company page puts those series for one ticker on one URL, with planned sales, large holders, 13F holders and financials beside them, so the short position, the daily flow, the settlement fails and what insiders are doing can be read together.
Each section has its own history table, a one-line summary of the latest figures and its own JSON and CSV links, and says when its source last updated.
This page follows Terrestrial Energy (IMSR), SEC CIK 2019804, listed on Nasdaq. The cross-market tables live on the short interest and insider transactions hubs.
Source and updates
- Short interest
- FINRA consolidated short interestSource: FINRA.Twice a month, about eight business days after settlement. Latest 2026-10-15.JSON and CSV
- Daily short volume
- FINRA Reg SHO daily filesSource: FINRA.Every trading day, the morning after FINRA posts it. Latest 2026-11-02.JSON and CSV
- Fails to deliver
- SEC fails-to-deliver dataSource: SEC.Twice a month, a few weeks after the half month ends. Latest 2026-10-14.JSON and CSV
- Large holders
- SEC EDGAR Schedule 13D and 13GSource: SEC.New filings appear shortly after the SEC posts them. A 13D is due within five business days of crossing 5%; a 13G follows the passive schedule. Latest 2026-02-17.JSON and CSV
- 13F holders
- SEC EDGAR Form 13F-HRSource: SEC.Quarterly, filed within 45 days of quarter end; 30 tracked managers. Latest 2026-06-30.JSON and CSV
- Earnings dates
- SEC EDGAR 8-K filings (Item 2.02)Source: SEC.Twice a day. Reported dates come from the company's 8-K filings; the next date is marked as an estimate until the 8-K arrives. Latest 2026-08-11.JSON and CSV
- Insider trades
- SEC EDGAR Form 4Source: SEC.New filings appear shortly after the SEC posts them; they're due two business days after the trade. Latest 2026-10-28.JSON and CSV
- Company record
- EDGAR filing index for CIK 2019804Ticker, name and exchange from the SEC's company list, refreshed weekly.
- Rate limits
- 10 requests a minute without a key, 30 with a free key from a free account.
How to read it
- Read the position against the flow: rising short interest with a high daily short share is new shorting; rising short interest with a normal short share is old shorts holding on.
- Insider buys next to a large short position are rare and stand out; insider sells next to one are common and mean little.
- Fails to deliver matter relative to the float, not in absolute shares; a million failed shares in a mega cap is noise.
Analysis of what the data shows, not advice. XOOMAR does not recommend buying, selling or holding anything.
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Datasets
Frequently Asked Questions
How much of IMSR is sold short?
What is IMSR's daily short volume?
Does IMSR have fails to deliver?
Are IMSR insiders buying or selling?
Who owns 5% or more of IMSR?
Which tracked 13F managers own IMSR?
Data on this page is provided for informational purposes only and is not financial advice. See our editorial policy.