Taiwanese chipmaker Visual Photonics Epitaxy (VPEC) surged to its daily limit as demand for optical components picked up — good news for holders, though a broad market slide trimmed the gain.

• The stock hit its limit-up price within half an hour of trading resuming after a regulatory trading restriction was lifted.
• Optical chip sales are booming, more than doubling from a year ago and now making up over a quarter of revenue.
• China approving some substrate shipments should push optical sales up sharply this quarter, even as a key substrate stays in short supply.
• The company is buying two extra chipmaking machines beyond its original plan to serve new US customer orders.
• Foreign investors have bought the stock five days running; profit forecasts point to earnings rising by half again next year.

Outlook: Growth looks set to accelerate this quarter, but the wider Taiwan market falling more than 600 points is capping how far the stock can run.