Rate-cut hopes have flipped into hike fears, and KOSPI has slid for a fourth straight session while Samsung and SK hynix lean on buybacks to hold the line
🎧 Post Summary
📌 1-Minute Summary
On September 15, KOSPI closed down 0.85% at 6,627.26, its fourth consecutive daily decline. The 10-year U.S. Treasury yield climbed back above 5%, and crude oil topped $100 a barrel. With the September FOMC meeting a day away, markets are now pricing in a roughly 90% chance of a rate hike rather than a cut. KOSDAQ bucked the trend, rising 0.70% on strength in cybersecurity and biotech names. Samsung Electronics and SK hynix continued large-scale share buybacks to offset foreign selling.
Just weeks ago, the market’s biggest question was when the Fed would start cutting rates. That calculus has flipped entirely ahead of the September 15-16 FOMC meeting. Markets are now leaning toward a hike, and KOSPI has slid for four straight sessions under the weight of that uncertainty. What triggered the reversal, and how are Korea’s chip giants holding up?
① KOSPI Closes at 6,627, a Fourth Straight Decline — Behind the Triple Threat
KOSPI opened at 6,659.25 on the 15th and briefly rallied to an intraday high of 6,715.46, but afternoon profit-taking dragged the index down 57.11 points (-0.85%) from the previous close of 6,684.37, to finish at 6,627.26 — a fourth consecutive daily decline since September 10. Three forces weighed on the market: the 10-year U.S. Treasury yield re-crossed 5%, fueling concerns over prolonged high rates; crude oil broke above $100 a barrel, reviving inflation worries; and anxiety over the September FOMC meeting compounded the pressure, with foreign and institutional investors together selling a net 2.4 trillion won.
② An Unusual Reversal — How Rate-Cut Hopes Turned Into Hike Fears
This FOMC meeting has drawn unusual attention because market sentiment flipped almost overnight. Before the Jackson Hole symposium on August 28, the probability of a September rate hike stood at just 35.4% on the CME FedWatch tool. But when Fed Chair Kevin Warsh struck a hawkish tone at Jackson Hole — warning that underlying inflation wasn’t cooling — sentiment shifted sharply. The hike probability jumped to 55.7% immediately after the speech and climbed further to 89-90% as of September 14. Warsh reportedly reaffirmed the PCE price index as the Fed’s key inflation gauge to address market doubts, while dismissing the idea of adopting a more flexible alternative model.
③ KOSDAQ Bucks the Trend — Cybersecurity and Biotech Strength Decouples It From KOSPI
KOSDAQ closed at 812.41, up 5.62 points (+0.70%) from the previous day’s 806.79, moving in the opposite direction from KOSPI. Cybersecurity stocks like Aton and Hancom WITH, along with biotech name Genbio, hit their daily upper limits, with sector-specific strength lifting the index. While large-cap chip stocks on KOSPI were buffeted by macro headwinds, KOSDAQ moved on its own set of catalysts.
④ Chipmakers’ Defense — Samsung and SK hynix Buybacks vs. Foreign Selling
Over the course of August, foreign investors net-sold 7.0596 trillion won of SK hynix, 1.4484 trillion won of Samsung preferred shares, and 819.8 billion won of Samsung common shares, concentrating their selling in large-cap chip names. Retail investors took the opposite side, net-buying 2.6418 trillion won of SK hynix and 2.2878 trillion won of Samsung over the same period. That dynamic has continued into September. Whether the two companies’ large-scale buybacks can absorb foreign selling — and which company shows stronger HBM4 supply expansion and yield improvement first — are seen as the key variables for chip stocks this month. Meanwhile, semiconductor exports surged more than 270% year-over-year in the first ten days of September, with total exports for the period hitting a record $35 billion, powered largely by chips.
📌 Investor Notes
- Volatility could increase around the FOMC announcement (September 16 local time); it may be safer to react after the decision rather than position ahead of it.
- The 90% figure is merely a market-implied probability — the actual decision will hinge on the combination of employment and inflation data.
- Buybacks may not fully offset foreign selling, so supply-and-demand dynamics bear continued watching.
- Even within the chip sector, HBM4 supply and yield issues could create diverging performance between individual stocks.
In short, the September FOMC meeting is this week’s single biggest variable for markets. A rate-hike scenario that would have seemed unthinkable just weeks ago is now priced in at roughly 90%, leaving KOSPI to catch its breath for a fourth straight session. Even so, Samsung and SK hynix are holding the line with large-scale buybacks, and semiconductor exports are on pace for a record. Once the FOMC decision lands, we’ll see which way this tug-of-war finally tips.
References
- Firebat – “September 15, 2026 KOSPI Closing Report | FOMC and High Oil Prices Push Index to Edge of 6,600” (firebat.co.kr)
- Money Today – “[Spot] KOSDAQ Closes Up 5.62 Points (0.70%) at 812.41” (mt.co.kr)
- CEO Magazine – “[Preview] Will the September FOMC Raise Rates? Outlook and Impact Analysis” (ceomagazine.co.kr)
- EBN News Center – “Samsung and SK hynix Diverge — September’s Key Variable Is Buybacks” (ebn.co.kr)
- eToday – “[Featured Stocks] Samsung and SK hynix Weaken Together as U.S. Chip Stocks Slump” (etoday.co.kr)
- Kori Insight – “September Week 3 Economic News Analysis: KOSPI Falls Below 7,000, Samsung, SK hynix, and Government Livelihood Policy” (koriinsight.com)