SK hynix absorbed 59% of foreign investors' month of net selling in Korean stocks

Take the two chipmakers out and the remainder is small. In Korea Exchange data, SK hynix's 12.009 trillion won and Samsung Electronics' 5.186 trillion won add up to 17.195 trillion won, about 85% of the 20.305 trillion won total ^[7][8][1][2]. That leaves roughly 3.1 trillion won of net foreign selling across every other stock on the main board for the month ^[3]. Foreigners sold a net 3 trillion won on Sept. 28 alone ^[4], so one session came close to matching a month of net selling in everything else ^[3].

The split inside the pair is uneven too, with hynix taking 2.3 times Samsung's selling ^[6]. The sources do not give index weights. Some of the concentration may be proportional selling in a market that is heavily weighted toward semiconductors, as Seoul Economic Daily describes it ^[17]. The ownership ratios are a better check. Even at its lowest in more than three years, foreign ownership of SK hynix sits about 10 percentage points above foreigners' 39.66% share of the KOSPI's total market value ^[6][5][4]. Samsung, at 46.41%, sits about 6.75 points above it ^[9][5].

Profit-taking after the first-half rally is the explanation both Seoul Economic Daily and the Korea Herald lead with ^[11]. It fits selling that lands hardest on the more heavily owned of the two chipmakers. Both outlets also cite the prolonged US-Iran war and rising interest rates in major economies ^[12]. A rates-driven cut to Korea exposure would also fall hardest on the largest foreign holdings, so the concentration by itself cannot separate the two explanations. There is a measurement issue as well: the totals include an after-market session that opened only on Sept. 15 ^[2], so the month does not compare cleanly with earlier ones.

In my view the profit-taking explanation fits the record best. Foreigners are trimming a memory position they still hold heavily, and the hynix ownership ratio tracks that better than the KOSPI total does. The view is wrong if chip shares steady after earnings and foreign selling then moves into the rest of the board, because that pattern would be a rates-driven exit from Korea. Lee Jae-won, an analyst at Yuanta Securities Korea, ties the recovery to rates. He said the shrinking scale of selling even on days of strong index gains, such as Oct. 1, "is the first sign that supply and demand could normalize once long-term interest rates stabilize" ^[16].

The early-October flows ^[10] are small against the period's average of about 923 billion won of net foreign selling per session ^[7]. Oct. 2's 190 billion won is about a fifth of that average ^[8]. Micron, the first of the three major memory makers to report, posted better-than-expected results on Sept. 30 ^[13]. "Macro jitters should peak this month, and the improved profit visibility after the third-quarter earnings season will serve as an incentive for foreign net buying," said Han Ji-young, an analyst at Kiwoom Securities ^[15].