Taiwan IC substrate maker Unimicron is under criminal investigation for relabelling China-made boards as "Made in Taiwan" — bad news for the stock, and for the growing list of active ETFs that loaded up on it.

• Prosecutors in Taoyuan searched Unimicron's head office and plant, questioned 14 people, and released five on bail, including the PCB unit's general manager and a vice president.
• The suspected offence is faking product origin labels on boards shipped back from China and passing them off as Taiwanese-made.
• The stock hit a record high the morning of the raid, then abruptly turned negative — investors now fear a sharp re-rating, with talk of the price halving.
• Several Taiwanese active ETFs hold large Unimicron positions, so the fallout spreads to fund holders who never picked the stock themselves.
• If US customers question where the boards were really made, orders could shift to rivals Kinsus and Nan Ya PCB.

Outlook: Monday's trading and whether big institutions and ETF managers cut their Unimicron stakes will set the tone, while prosecutors widen the probe.