Samsung and SK Hynix power half the Kospi, and that concentration cuts both ways
Some of the world's largest fund managers spent this year selling South Korean stocks, and not because they lost faith in them.
As CNBC reported, citing Korea Exchange data, overseas investors had unloaded a net of about US$801m in Kospi-listed shares by midday Monday in Seoul, while Goldman Sachs estimated net foreign outflows of roughly US$62bn by late May.
Reuters reported foreigners had been net sellers for 21 straight sessions.
Yet the selling says more about success than conviction: the Kospi remains up 78 percent year-to-date, after a 76 percent gain in 2025 that ranked as its best year since 1999.
The mechanics are structural.
As Korean stocks surged, their weightings in global and emerging-market benchmarks rose sharply, pushing active managers to trim positions to stay within risk limits, investors told CNBC.
Chetan Seth, Nomura's Asia-Pacific equity strategist, described "essentially forced selling" from investors and clients.
Nick Wilcox of Man Group pointed to a second driver: investors hitting regulatory caps on individual holdings, "coming up against active limits," he told the outlet.
Domestic buyers more than absorbed the exodus, Wilcox added, pointing to an estimated US$70bn in retail inflows this year.
That dependence on a handful of names is the bigger risk for anyone holding the index.
Reuters reported Samsung Electronics and SK Hynix now account for more than half the Kospi, with their market values up over 150 percent and 200 percent this year, placing each in the US$1tn club.
CNBC noted the pair make up more than 40 percent of the benchmark, magnifying its swings in both directions.
Those swings turned violent this week.
The Kospi closed down 8.3 percent on Monday, its steepest drop since March 4, tripping circuit breakers for only the ninth time in its history, according to Reuters.
The index then rebounded Tuesday, CNBC reported, with SK Hynix up 6.44 percent and Samsung gaining 3.38 percent as buyers returned to AI-linked names.
The trigger came from the United States.
The global sell-off began after Broadcom's quarterly revenue missed estimates, then deepened on Friday when strong US jobs data pushed back expectations for rate cuts.
Goldman Sachs has pushed the final two rate cuts in its Fed forecast back to June and December 2027, the bank said in a Friday note.
"The labor market has been stronger than we anticipated."
Strategists who spoke to Reuters largely read the drop as a repositioning rather than a turn in the story.
"The move looks more like a positioning and momentum unwind than a reassessment of the long-term AI story," said Marc Velan of Lucerne Asset Management, adding that the key question is whether hyperscaler AI spending slows, with no sign of that yet.
Seth described the foreign selling to CNBC as "mechanical right now."
Thomas Mathews of Capital Economics told Reuters that chipmakers are "still making lots of money and the broader economy is strong, which isn't typically a backdrop for a sustained drawdown."
The cautions centre on leverage and liquidity.
Frank Benzimra of Societe Generale told Reuters that leveraged ETFs were "amplifying the decline," while OCBC's Vasu Menon warned a heavy IPO calendar could drain money from existing tech holdings.
CNBC reported OpenAI has confidentially filed to go public, following Anthropic, with SpaceX shares expected to start trading Friday; OpenAI is valued at more than US$850bn.
For now, the policy and price signals point higher.
Reuters reported the won rallied more than 1 percent after South Korean authorities vowed action against speculative trading, with president Lee Jae Myung calling the market "still undervalued."
Goldman Sachs has stayed bullish, CNBC reported, lifting its 12-month Kospi target to 12,000 and forecasting a further 37 percent upside.
