Comparable stake leader
BAILLIE GIFFORD & CO
SEC ownership of Adaptimmune Therapeutics PLC
Top holders, 13D/G large-stake signals, insider positions, and transaction flow tied to CIK 0001621227.
Disclosed value leader
BAILLIE GIFFORD & CO
Comparable rows
3/21
Latest evidence
28 Aug 2025
- Parsed ownership sources
-
13D/G and 3/4/5
Source: Parsed SEC ownership filingsUse: Compare filing families carefully
- Largest SEC-reported holder
-
BAILLIE GIFFORD & CO
Ranking: Comparable ownership first, then disclosed value
- Comparable ownership rows
-
3 of 21
Meaning: Rows with safely comparable ownership %
- Latest 13D/G holder
-
BAILLIE GIFFORD & CO
Source: Latest parsed Schedule 13D/G stake
- Latest parsed ownership date
-
28 Aug 2025
Freshness: Most recent filing date in this holder set
- Issuer CIK
- 0001621227
- Issuer location
- Abingdon, Oxfordshire
Ownership snapshot
CIK-linked ownership evidence from parsed SEC filings.
3 signals
Issuer
Names, identifiers, and filing context for this profile.
2 identity fields
Ownership snapshot
Top shareholders of Adaptimmune Therapeutics PLC (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
BAILLIE GIFFORD & CO
Disclosed value leader
BAILLIE GIFFORD & CO
Comparable rows
3/21
Latest evidence
28 Aug 2025
13D/G
3/4/5
Lead comparable stake: 4.6%
18 rows are not safely comparable across share classes.
13D/G row: BAILLIE GIFFORD & CO
Showing 1-8 of 21 holder rows.
Quick read
BAILLIE GIFFORD & CO leads the comparable SEC ownership view at 4.6%.
3 of 21 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 BAILLIE GIFFORD & CO's linked filing trail.
Comparable ownership
Top 3
BAILLIE GIFFORD & CO
4.6%
EcoR1 Capital, LLC
4.2%
New Enterprise Associates 14, L.P.
0%
Ownership % is shown only when SEC disclosures are safely comparable across share classes.
Detailed SEC evidence table Showing 1-8 of 21 holder rows
| Holder | Evidence | Ownership % | Position | 12M Net Δ | As of |
|---|---|---|---|---|---|
| BAILLIE GIFFORD & CO |
13D/G
|
4.6%
|
$19,146,934
70,914,570 shares
|
$0 | 31 Dec 2024 |
| EcoR1 Capital, LLC |
3/4/5
13D/G
10%+ Owner
|
4.2%
from 13D/G
|
$10,247,969
100,371,882 shares
|
— | 28 Jul 2025 |
| New Enterprise Associates 14, L.P. |
13D/G
|
0%
|
$0.4
4 shares
|
$0 | 15 Aug 2025 |
| William C. Bertrand Jr. |
3/4/5
Chief Operating Officer
|
—
mixed-class rows
|
$102,997
2,068,558 shares
mixed-class rows
|
— | 28 Aug 2025 |
| Garry E. Menzel |
3/4/5
Director
|
—
mixed-class rows
|
$50,513
1,196,660 shares
mixed-class rows
|
— | 01 Jul 2024 |
| Adrian Rawcliffe |
3/4/5
Chief Executive Officer, Director
|
—
mixed-class rows
|
$25,745
3,473,159 shares
mixed-class rows
|
— | 20 Feb 2025 |
| Cintia Piccina |
3/4/5
Chief Commercial Officer
|
—
mixed-class rows
|
$10,588
1,093,117 shares
mixed-class rows
|
— | 20 Feb 2025 |
| Elliot Norry |
3/4/5
Chief Medical Officer
|
—
mixed-class rows
|
$4,362
1,082,206 shares
mixed-class rows
|
— | 20 Feb 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.
Forms 3/4/5 flow
Insider trading overview
Insider buy and sell flow is broadly balanced over the last 12 months. No Buy or Sell transactions have been reported since 28 Sep 2025.
Buys
$0
Insiders: 0
Sells
$0
Insiders: 0
Net
$0
Shares: 0
Window
Last 12 months
4 rolling buckets
Buy value
Sell value
Shares: 0
Shares: 0
| Window (months) | Buy shares | Sell shares | Buy value | Sell value | Net value |
|---|---|---|---|---|---|
| 0-3 | 0 | 0 | $0 | $0 | $0 |
| 3-6 | 0 | 0 | $0 | $0 | $0 |
| 6-9 | 0 | 0 | $0 | $0 | $0 |
| 9-12 | 0 | 0 | $0 | $0 | $0 |
Reporting owners
Insider holders from Forms 3/4/5
Showing 1-20 of 22 reporting-owner rows connected to Adaptimmune Therapeutics PLC. Open a relationship link for the CIK-to-CIK filing trail.
Rows
22
Largest Forms 3/4/5 holder
EcoR1 Capital, LLC
Net 12M change
$0
Latest report
10 Sep 2025
Recent insider transactions for Adaptimmune Therapeutics PLC
Showing up to 300 recent insider transactions from the last 12 months.
| Insider | Symbol | Class | Transaction | % | SEC-reported value | SEC-reported price | Shares | Shares owned | Date | Ownership |
|---|---|---|---|---|---|---|---|---|---|---|
| No insider transactions were found in the last 12 months for this issuer. | ||||||||||
* marks a reported price that did not pass the local price check.