Montage Technology (6809.HK) tumbled over 8% to HK$307.2 during regular trading.
The decline came as the semiconductor sector weakened broadly. At press time, Hua Hong Semiconductor fell 7.68%, while GigaDevice slipped 7.48%. Earlier, Citigroup reiterated a buy rating, citing strong fundamentals but noting pressure from industry-wide adjustments and fallout from South Korea's antitrust probe.