SEOUL, July 8 : Shares of South Korean memory chipmakers Samsung Electronics and SK Hynix fell as much as 4.4 per cent and 5 per cent, respectively, in early morning trade on Wednesday, tracking a broad selloff in U.S. semiconductor stocks after investors grew increasingly concerned about the sustainability of the AI-driven chip boom. High-flying memory and semiconductor stocks tumbled overnight, with Intel, Micron and AMD closing down 9.7 per cent, 4.7 per cent and 6.5 per cent, respectively. [MKTS/GLOB] Also, the Philadelphia Semiconductor Index lost 4.7 per cent as investors questioned whether AI-related spending can be sustained.