Asian semiconductor shares fell on Thursday, led by steep declines in Japan and South Korea, as investors assessed mixed results from Qualcomm and Arm and questioned whether heavy artificial-intelligence infrastructure spending will generate sustainable returns. Qualcomm shares dropped more than 9% in extended U.S. trading after fourth-quarter handset-chip revenue missed expectations, underscoring pressure on its core smartphone business. Arm reported quarterly revenue and earnings above analyst estimates, but royalty revenue rose 8% to $670 million, below forecasts, sending its shares down about 3% after hours. Samsung Electronics fell 5.7%, SK Hynix lost 7.4%, Advantest declined more than 11%, Lasertec dropped 12.5% and Kioxia fell 9.2%. Chinese semiconductor stocks mostly rose as Beijing's latest market-support measures boosted demand for domestic chipmakers.