The Short Answer
At the Korean close on August 28, 2026, SK Hynix settled at KRW 1,653,000, -4.45% on the day.
The circulating explanation is "foreign investors are fleeing." Broken down by investor type, that explanation does not hold.
Foreign investors net-sold 190,235 shares — just 6.80% of the day's volume. Domestic institutions net-sold
796,000 shares, or 28.46% — 4.18x the foreign leg. The foreign ownership ratio slipped only from
50.63% to 50.60%, essentially unchanged. This session was sold by domestic institutions, not foreigners.
The Data: The Two Legs Must Be Read Separately
Figures below are settled Korea Exchange closing data for 2026-08-28. Net-sell ratio = net shares sold ÷ same-day volume.
| Name | Close (KRW) | Day | Volume | Foreign net-sell | Domestic institutional net-sell | Combined | Foreign ownership |
|---|---|---|---|---|---|---|---|
| SK Hynix (000660) | 1,653,000 | -4.45% | 2,796,942 | 6.80% | 28.46% | 35.26% | 50.63% → 50.60% |
| Samsung Electronics (005930) | 257,000 | -3.38% | 14,698,877 | 13.11% | 11.24% | 24.35% | 46.73% → 46.72% |
Why Reading Only the Foreign Leg Inverts the Conclusion
This is the part worth remembering. The two-day change in SK Hynix's foreign leg:
- Aug 27: foreign net-sell = 5.05% of volume
- Aug 28: foreign net-sell = 6.80% of volume (wider by only +1.75 pp)
On that leg alone, August 28 looks like a mild continuation of the prior day — nothing unusual.
Add domestic institutions:
- Aug 27: combined net-sell = 9.49% of volume
- Aug 28: combined net-sell = 35.26% of volume — a 3.7x jump
The entire event sits in the domestic institutional leg. Most financial coverage quotes foreign flows only. On this
particular day that metric carries almost no information, and it points readers toward "foreigners are fleeing" — the
opposite of what the data shows.
The Two Names Were Not Sold by the Same People
Treating "Korean memory" as a single trade hides a material difference:
| Domestic institutional ÷ foreign | Character of the selling | Foreign leg prior day (Aug 27) | |
|---|---|---|---|
| SK Hynix | 4.18x | Domestic-institution driven | net sell 5.05% |
| Samsung Electronics | 0.86x | Both legs roughly comparable | net BUY 8.32% |
Samsung's foreign leg genuinely reversed: from net buying 8.32% of volume on Aug 27 to net selling 13.11% on Aug 28.
Hynix's foreign leg simply continued two days of modest net selling, with no reversal.
Same day, same sector — but the sellers were not the same people.
The US Tape: Rotation Inside the Same Semiconductor Basket
Settled August 27 (US) — gains ranked strictly by proximity to AI compute, with memory negative:
| NVIDIA | Broadcom | TSMC | Semis ETF (SMH) | Nasdaq ETF (QQQ) | S&P ETF (SPY) | AMD | Micron | SanDisk |
|---|---|---|---|---|---|---|---|---|
| +8.74% | +4.49% | +2.30% | +3.10% | +1.37% | +0.66% | -0.89% | -0.32% | -0.96% |
That +3.10% in the semiconductor ETF was carried entirely by NVIDIA, Broadcom and TSMC.
"The semis ETF is up" is not the same as "semiconductors are up."
August 28 intraday (as of 2026-08-28 10:34 ET — ⚠️ this session has NOT settled; these numbers will still move) —
almost a mirror image of the prior day:
| Micron | SanDisk | Western Digital | Semis ETF (SMH) | NVIDIA | Broadcom | TSMC | AMD | Nasdaq ETF |
|---|---|---|---|---|---|---|---|---|
| +1.04% | +1.91% | +2.11% | -1.13% | -1.25% | +0.21% | -0.28% | +0.06% | -0.01% |
Memory up, compute down — the direction from the previous session is fully reversed.
This is rotation within semiconductors, not a move in the sector as a whole.
What This Data Does NOT Establish
- It does not establish a memory-specific problem. Micron's spread versus the semis ETF across three sessions was
+0.59pp (Aug 26, settled), -3.42pp (Aug 27, settled) and +2.17pp (Aug 28, intraday) — it oscillates,
with no sustained underperformance trend. - It says nothing about valuation. Memory is cyclical: earnings fall faster than price, so P/E is highest at the
trough. The percentile reads backwards. - It does not establish a new de-risking cycle. A single day of 28.46% domestic institutional net selling is a
spike until it repeats.
What to Watch Next
- Whether the combined net-sell ratio retreats. Back below 10% = single-day spike. Two consecutive sessions above
20% = a new round of de-risking is real. - Whether Samsung's foreign ownership ratio (46.72%) falls a second consecutive day. This is a slow-moving
variable; a turn in it means more than any single day of flow. - The August 28 US close. Whether the intraday memory bounce holds into the settlement determines whether that
spread is oscillation or an inflection.
Method and Definitions
- Korea: Korea Exchange investor-type trading data, settled close for 2026-08-28. Net-sell ratio = net shares sold ÷
same-day volume (same source, same day). - US: August 27 figures are settled closes; August 28 figures are live intraday quotes, with the as-of stamp shown
inline. The two are never mixed. - Korea closes 14:30 KST and the US closes 16:00 ET — different time windows, so no cross-market ratio of daily returns
is computed here. - This is public-layer market-structure analysis. It contains no position, sizing or trade-execution information and is
not investment advice.