Taiwan's chip substrate stocks are selling off, a bad sign for investors betting on an endless AI hardware boom, though buyers may get cheaper entry points.

• Nanya PCB fell more than 6% and Unimicron more than 4%, both on heavy trading volume.
• Nanya PCB is reportedly holding BT substrate prices flat next quarter because raw material costs have stopped climbing fast.
• Broadcom said it will build its own substrate capacity in Singapore from 2027, easing the shortage that drove prices up.
• Kinsus bucked the trend and rose, splitting the group as money rotates to whatever still looks strong.
• Taiwan's main index gave up an early 350-point gain and closed down, with the over-the-counter index falling harder.

Outlook: Substrate stocks look set to keep swinging until AI server demand and company guidance give a clearer signal.