The memory business has rarely had it this good, thanks to the artificial intelligence (AI) boom. Korea’s chipmakers are reporting extraordinary earnings and unusual confidence that the good times will last. SK hynix’s third-quarter operating profit rose more than sevenfold to 83.3 trillion won ($62 billion), an operating margin of almost 80 percent. Samsung Electronics’ rose nearly ninefold to 107.4 trillion won, with its memory business setting records of its own. Across the West Sea, China’s challengers are sharing in the windfall. ChangXin Memory Technologies (CXMT) remains far smaller, but its quarterly revenue rose more than sevenfold to 118.7 billion yuan ($17.8 billion), with a net profit attributable to shareholders of 54.4 billion yuan, reversing years of losses. CXMT and Yangtze Memory Technologies (YMTC) are the twin pillars of China’s drive for memory self-sufficiency, part of Beijing’s broader pursuit of technological independence facing U.S. export restrictions. Fresh capital, new factories and increasingly sophisticated technology are helping them challenge th