Terrestrial Energy Inc. (IMSR) has 12 known insider and institutional holders on record. The largest holder is Sella Roberto Marco with 180,316 shares. Other notable holders include Irish Simon and Brenner Andrew Scott.
Over the last 12 months, insiders have made 36 transactions in IMSR stock — 13 buys (valued at RSU Award) and 0 sells (valued at RSU Award). Insider buying has outpaced selling during this period, which may signal confidence in the company's prospects.
IMSR Insider Ownership
Top Holder
Sella Roberto Marco
180,316 shares
Buys (12 mo)
13
$0.00 value
Sells (12 mo)
0
$0.00 value
12-Month Transaction Activity
Top Insider Holders
| # |
Name |
Role |
Shares Owned |
Last Filed |
Relative Size |
| 1 |
Sella Roberto Marco |
10 Percent Owner |
180,316 |
2026-01-22 |
|
| 2 |
Irish Simon |
Chief Executive Officer |
166,298 |
2025-10-30 |
|
| 3 |
Brenner Andrew Scott |
Other: Former Director |
25,000 |
2025-10-30 |
|
| 4 |
Connor Michael J |
Other: Former Director |
25,000 |
2025-10-30 |
|
| 5 |
Loveless Jacob |
Other: Former Director |
25,000 |
2025-10-30 |
|
| 6 |
Johnson William D |
Director |
6,894 |
2026-01-09 |
|
| 7 |
Buckman Frederick W |
Director |
6,703 |
2025-12-22 |
|
| 8 |
Jones Robert Wood |
Director |
5,865 |
2025-12-22 |
|
| 9 |
Macdiarmid John Hugh |
Director |
5,865 |
2025-12-22 |
|
| 10 |
Pardee Charles G |
Director |
5,027 |
2025-12-22 |
|
| 11 |
Matthews Shawn |
Director |
4,190 |
2025-12-22 |
|
| 12 |
Hill David John |
Director |
3,352 |
2025-12-22 |
|
Recent Transactions (last 12 months)
| Date |
Name |
Role |
Type |
Shares |
Price |
Value |
| 2025-10-29 |
Sella Roberto Marco |
10 Percent Owner |
Unknown |
- |
- |
- |
| 2025-02-21 |
Sella Roberto Marco |
10 Percent Owner |
Unknown |
670,544 |
$2.24 |
$1.5M |
| 2025-12-18 |
Johnson William D |
Director |
RSU Award |
1,029 |
- |
- |
| 2025-12-18 |
Macdiarmid John Hugh |
Director |
RSU Award |
5,865 |
- |
- |
| 2025-12-18 |
Hill David John |
Director |
RSU Award |
3,352 |
- |
- |
| 2025-12-18 |
Matthews Shawn |
Director |
RSU Award |
4,190 |
- |
- |
| 2025-12-18 |
Pardee Charles G |
Director |
RSU Award |
5,027 |
- |
- |
| 2025-12-18 |
Jones Robert Wood |
Director |
RSU Award |
5,865 |
- |
- |
| 2025-12-18 |
Johnson William D |
Director |
RSU Award |
5,865 |
- |
- |
| 2025-12-18 |
Buckman Frederick W |
Director |
RSU Award |
6,703 |
- |
- |
| 2025-11-06 |
Matthews Shawn |
Director |
Other (Sell) |
3,500,000 |
$11.50 |
$40.25M |
| 2025-10-28 |
Leblanc David Michael |
Chief Technology Officer |
Unknown |
- |
- |
- |
| 2027-06-20 |
Smith William F. |
Chief Operating Officer |
Unknown |
134,109 |
$7.83 |
$1.05M |
| 2025-10-28 |
Smith William F. |
Chief Operating Officer |
Unknown |
111,758 |
$2.01 |
$225K |
| 2024-04-01 |
Smith William F. |
Chief Operating Officer |
Unknown |
156,461 |
$2.24 |
$350K |
| 2025-10-28 |
Macdiarmid John Hugh |
Director |
Unknown |
- |
- |
- |
| 2024-04-01 |
Macdiarmid John Hugh |
Director |
Unknown |
78,231 |
$2.24 |
$175K |
| 2026-10-21 |
Irish Simon |
Chief Executive Officer |
Unknown |
1,023,160 |
- |
- |
| 2025-10-28 |
Irish Simon |
Chief Executive Officer |
Unknown |
- |
- |
- |
| 2024-07-14 |
Irish Simon |
Chief Executive Officer |
Unknown |
178,812 |
$2.24 |
$400K |
| 2026-04-30 |
Thrasher Brian Patrick |
Chief Financial Officer |
Unknown |
156,461 |
$7.83 |
$1.23M |
| 2026-07-09 |
Millsap Steven M. |
Gc, Sec'y & Chief Comp. Off'r |
Unknown |
134,109 |
$9.17 |
$1.23M |
| 2025-10-28 |
Hill David John |
Director |
Unknown |
- |
- |
- |
| 2024-04-01 |
Hill David John |
Director |
Unknown |
67,055 |
$2.24 |
$150K |
| 2025-10-28 |
Pardee Charles G |
Director |
Unknown |
- |
- |
- |
