LIN SANDRA BEACH 4

What Happened

• Sandra Lin, a director of Trinseo PLC (TSE), recorded an other disposition (code J) on May 12, 2026: the forfeiture of 42,484 restricted stock units (RSUs) previously granted on June 25, 2025. The award was unvested at forfeiture; no per-share price or cash proceeds are reported.

Key Details

• Transaction date: 2026-05-12 (filed with the SEC on 2026-05-14)
• Transaction type/code: Other disposition (J) — voluntary forfeiture of RSUs
• Shares/units affected: 42,484 RSUs forfeited
• Price/Proceeds: N/A — forfeiture, not an open-market sale
• Shares owned after transaction: Not specified in the filing
• Footnote: Confirms RSUs were unvested and forfeited (granted June 25, 2025)

Context

• A forfeiture cancels unvested equity awards and is not a purchase or market sale; it does not generate cash proceeds for the insider. Such forfeitures commonly occur under grant or employment-plan terms (e.g., termination, voluntary forfeiture), but the filing does not state a reason. This filing appears timely (reported two days after the transaction).