SCHEDULE 13G/A

Trinseo PLC

Ordinary Shares, par value $0.01 per share · CUSIP: G9059U107

Event date: 2025-12-31

Reporting persons may disclose overlapping interests. Their amounts are shown individually and are not added into a filing total.

Filing-level shares

Unavailable

Percent of class

Unavailable

• CastleKnight Master Fund LP

  Shares: 516,826.00 · Class: 1.4%

• CastleKnight Fund GP LLC

  Shares: 516,826.00 · Class: 1.4%

• CastleKnight Management LP

  Shares: 516,826.00 · Class: 1.4%

• CastleKnight Management GP LLC

  Shares: 516,826.00 · Class: 1.4%

• Weitman Capital LLC

  Shares: 516,826.00 · Class: 1.4%

• Aaron Weitman

  Shares: 516,826.00 · Class: 1.4%

Amounts are as disclosed in this filing. Schedule type alone does not establish investment intent.