Taiwan's top IC substrate maker Unimicron crashed to the daily loss limit after prosecutors opened a probe into whether it relabelled China-made products as "Made in Taiwan," a hit to shareholders but one analysts call contained.

• Unimicron opened locked at limit down with a mountain of sell orders piled up and no buyers.
• Prosecutors in Taoyuan questioned 14 people over the origin-labelling case; several were released on bail, including a division head who posted a large bond.
• Local analysts call this a compliance failure, not fake accounting, and see little damage to core earnings; the odds of landing on the US entity list look very low.
• High-end ABF substrates are still in short supply worldwide, and rivals like Nan Ya PCB, Kinsus and Ibiden have no spare capacity to take the orders.
• The wider Taiwan market fell too, dropping through 46,000 as TSMC, MediaTek and Foxconn all slid on hawkish comments from Fed chair Warsh.

Outlook: The worst case looks like fines, back taxes and criminal charges for individuals, but Taiwanese firms that have long blurred cross-strait production lines now face much tighter US scrutiny.