Taiwan's stock market swung wildly Thursday, and chipmaker UMC — a favorite of over a million small shareholders — got hit hardest as domestic funds sold heavily.

• Taiwan's main index jumped over 400 points early on tech strength, then flipped to a loss before closing up 214 points.
• UMC opened strong on foreign buying but sank back to flat after local investment funds dumped 28,000 lots — by far their biggest sale of the day.
• Memory chip stocks and a late push in TSMC rescued the index from closing in the red.
• Domestic funds were net sellers across the board, also unloading banks like Hua Nan and Mega, plus Wan Hwa, ASE and other chip names.

Outlook: UMC's million-plus small shareholders are stuck between foreign buyers and local funds heading for the exit, so more choppy trading is likely.