Trinseo PLC
TSEOQ- Exchange
- OTC
- Industry
- Plastic Materials, Synth Resins & Nonvulcan Elastomers
- SEC CIK
- 0001519061
No open-market purchases or sales by Trinseo PLC insiders were filed in the last 90 days; 6 institutions reported holding it in 13F filings for Q2 2026, worth $740 in total; no superinvestor holds it.
Holders of 5% or more of TSEOQ
Holders whose latest Schedule 13D or 13G filing reports 5% or more of Trinseo PLC, largest stake first. The change is against the holder's previous filing.
| Holder | Latest form | Stake | Change | First filed | Latest filing | Filing |
|---|---|---|---|---|---|---|
| BlackRock, Inc. | 13G | 6.30%2.26M shares | New | Jul 17, 20251 filing | Jul 17, 2025 | SEC |
| Charles Schwab Investment Management Inc | 13G | 5.80%2.09M shares | New | Feb 12, 20261 filing | Feb 12, 2026 | SEC |
Stakes are as of each holder's latest filing. Holders whose last filing was in the old format (before December 18, 2024) have no stake on record and are not listed, and after an acquisition or delisting holders usually stop filing.
13D and 13G filings
4 Schedule 13D and 13G filings on Trinseo PLC, newest first, including old-format filings without a stake.
| Filed (ET) | Filer | Form | Stake | Change | Event date | Filing |
|---|---|---|---|---|---|---|
| Feb 17, 20265:18 PM ET | CastleKnight Master Fund LPand 5 others | 13G/A | 1.40%516.8K shares | −6.40 ppfrom 7.80%Below 5% | Dec 31, 2025 | SEC |
| Feb 12, 20263:20 PM ET | Charles Schwab Investment Management Inc | 13G | 5.80%2.09M shares | New | Dec 31, 2025 | SEC |
| Aug 14, 20257:06 PM ET | CastleKnight Master Fund LPand 5 others | 13G/A | 7.80%2.77M shares | – | Jun 30, 2025 | SEC |
| Jul 17, 20257:44 PM ET | BlackRock, Inc. | 13G | 6.30%2.26M shares | New | Jun 30, 2025 | SEC |
Form 144: proposed insider sales
Notices from officers, directors and other affiliates planning to sell Trinseo PLC shares.
No Form 144 notices for Trinseo PLC are on file.