Hot US inflation hit a Kospi whose 55 trillion won of chipmaker buybacks had wound down

SK Hynix lost 11.4% ^[7] and Kioxia 11.2% ^[10], an average of 11.3% ^[23], while TSMC lost 2.2% ahead of its earnings report ^[12] and Taiwan's Taiex 3% ^[11]. The two memory names fell about five times as hard as TSMC ^[24], though TSMC had its own results to trade around, which muddies the comparison. A rate shock should mark down every AI earnings stream by roughly the same fraction. This one did not, and the gap points at something specific to memory.

Seoul Economic Daily names the candidate. It says the common shock in both the July and October selloffs is the advance of China's ChangXin Memory Technologies and the fear of more memory supply ^[29], and that this month's trigger was news of new CXMT technology and plans to launch server DDR5 products ^[30]. July's version took the Kospi down 32.64%, from 8,303.41 on the 1st to 5,593.56 on the 30th ^[14]. The calendar is awkward for a pure inflation story. The US data came out on the 14th ^[4] and the 15th was the seventh straight session lower ^[2], so six of the seven losses came before the print ^[18].

The buyers were also missing. Samsung Electronics' 15 trillion won and SK hynix's 40 trillion won buyback programs, 55 trillion won between them ^[25], supported the market in August and September and have effectively wound down this month, according to Seoul Economic Daily ^[20]. With both programs done, the companies' own bid is gone, and foreign investors appear to be moving money from Korean equities into US assets ^[16]. Eun Chi-kwan, head of equity management at Korea Investment Management, said: "Trading value from individuals has plunged and institutional money is unlikely to flow in, so there is not enough domestic demand to absorb what foreigners are selling." ^[15]

The rate channel is real all the same. Seoul Economic Daily says the data raised the odds of a rate increase ^[4] and that slowing revenue growth at Anthropic deepened doubts about AI infrastructure spending ^[5]. Lee Jin-woo, head of the research center at Meritz Securities, said: "Three months ago, the core question was whether companies could recover the money they had invested in AI and turn a profit. Now the question is whether they can keep investing at all, with funding costs higher," ^[6]. SoftBank, an OpenAI investor, lost 9.4% ^[13], a move that fits the funding-cost story better than the memory-supply one. The CPI step behind it was 0.3 points ^[19].

We think the print was an accelerant, or rather a multiplier, on a market already coming apart for memory-specific and flow reasons, so the rate-shock reading of AI exposure is half right. The counter-thesis is the Meritz one: if funding cost is the live question, inflation is the cause and CXMT the backdrop. A third outcome is that both hold and the next CPI print does more damage than this one.

The tests are numeric. At 5,554.22 the Kospi sits 13.2% below the 14th's 200-day line of 6,395.03 ^[26], more than double the 6% gap that day ^[21], and regaining the line takes a 15.1% rally ^[27]. Since 1995, 91 of 124 breaks below that line, or 73.4%, were recovered within two weeks, which leaves 33 that were not ^[22][28]. In July the line came back in two days ^[22]. A rally through 6,395 with no buyback restart and no retail buyers would mean we over-read the flow problem. If TSMC's losses widen to match memory's while CXMT news stays quiet, the rate reading wins.