Taiwan chipmaker UMC jumped 6% on a wave of buying tied to silicon photonics, a good day for its shareholders and a sign money is rotating back into the stock.

• UMC briefly hit its daily limit before closing up 6%, reclaiming both its 5-day and monthly average lines.
• Trading volume was the heaviest of any stock on the Taiwan market.
• All three major investor groups bought: foreign funds added for a fourth straight day, local investment trusts snapped a three-day selling streak, and dealers kept buying.
• The spark is UMC's tie-up with Singapore chip designer SILITH, whose Singapore plant has now shipped its first mass-produced silicon photonics wafers.

Outlook: If silicon photonics moves from development into real volume production, UMC's years of investment could start showing up in sales.