KOSPI's Wildest Week: How Microsoft's Earnings Beat Turned a Historic Crash Into a Record Rebound
KOSPI's Wildest Week: How Microsoft's Earnings Beat Turned a Historic Crash Into a Record Rebound
If you blinked between July 22 and July 31, you missed a market cycle that normally takes years to complete. Korea's KOSPI index went from an all-time high, to its worst monthly decline since records began in 1990, to its single largest one-day percentage gain in history — all inside ten trading sessions. I have covered Korean equities for two decades, through the 2008 crisis, the 2020 pandemic crash, and more taper tantrums than I care to count. I have never seen a week like this one. And the strangest part is that the hero of the rebound wasn't a Korean company, a Korean regulator, or even an Asian market at all. It was Microsoft's earnings call, delivered nine time zones away in Redmond, Washington.
This piece pulls apart that week — the crash, the rebound, the Fed decision sitting awkwardly in the middle of it, and what all three mean for how you should think about Korean tech exposure heading into August. I'll try to keep it entertaining, because honestly, if you can't laugh a little at a market that fell 34% and then rallied 18% within days, you probably shouldn't be reading financial news at all.
1. The Week That Broke Every Rule
Let's set the scene. On July 22, the KOSPI closed at an all-time high of 9,114.55, riding a spectacular AI-driven semiconductor rally that had made Samsung Electronics and SK Hynix two of the best-performing large-cap stocks on the planet in 2026. Six trading days later, on July 28, the index had cratered to 6,023.66 — a single-day drop of 10.84% that triggered circuit breakers on both the KOSPI and KOSDAQ. The next day, July 29, it kept falling, touching an intraday low of 5,511.25. Measured from the July 1 close, that intraday low represented a monthly decline of roughly 33.6% — worse than October 1997 during the Asian Financial Crisis (-27.25%) and worse than October 2008 during the Global Financial Crisis (-23.13%). By any measure available since 1990, this was the worst month the Korean stock market has ever recorded.
Then, on July 31, the index closed at 6,595.45 — up 17.91% in a single session, the largest one-day percentage gain in KOSPI history. Samsung Electronics jumped roughly 26.8%. SK Hynix surged nearly 30%, hitting its daily upper limit. If you had described this chart to me in advance without dates attached, I would have guessed you were describing a small-cap biotech stock awaiting FDA news, not the benchmark index of the world's tenth-largest economy.
2. Anatomy of a Crash: How KOSPI Fell From 9,114 to 5,511
No single villain caused this. It was a convergence of three separate pressures that happened to arrive at once, each amplifying the other.
First, Samsung Electronics and SK Hynix together account for more than half of KOSPI's total market capitalization — an extraordinary concentration for a major index. When China's domestic memory-chip industry showed signs of catching up faster than expected, threatening the long-term thesis behind Korea's AI-chip rally, the two stocks fell together, and because they are more than half the index, the index fell with them almost one-for-one.
Second, foreign investors turned into aggressive net sellers, dumping roughly KRW 17.9 trillion (about $13 billion) worth of Korean shares across the KOSPI and KOSDAQ markets in July alone, with a single-day sale of nearly KRW 5 trillion on July 28. Bloomberg described the move bluntly: Korean retail investors were left reeling as the index posted its worst monthly drop on record.
Third, and this is the part that made the crash so much sharper than it needed to be — retail investors had piled into newly launched single-stock leveraged ETFs tracking Samsung and SK Hynix, first listed on May 27, 2026. These products amplify daily moves, which is a wonderful feature on the way up and a genuinely brutal one on the way down. I'll get into the regulatory fallout from this later, because Seoul's financial authorities moved with a speed I have rarely seen from any regulator, anywhere.
KOSPI's ten-day round trip, July 22–31, 2026. Source: Korea Exchange, Yonhap, Herald Corp.
Table 1 — KOSPI's July 2026 in Numbers
| Metric | Value |
|---|---|
| All-time closing high (Jul 22) | 9,114.55 |
| Record one-day drop (Jul 28) | -10.84% (close: 6,023.66) |
| Intraday low (Jul 29) | 5,511.25 |
| Record one-day gain (Jul 31) | +17.91% (close: 6,595.45) |
| July monthly decline (peak to trough) | ~-33.6% to -33.9% |
| Foreign net selling in July | ~KRW 17.9 trillion |
| Market cap lost (Jun close to Jul 28) | ~KRW 2,456 trillion (-32.97%) |
3. Enter Microsoft: The Earnings Call That Changed Everything
Here is where the story leaves Seoul entirely and heads to Redmond. On July 29-30, Microsoft reported fiscal fourth-quarter results that landed like a shot of adrenaline into a market that badly needed one. Azure revenue growth came in at roughly 43% year-over-year, comfortably ahead of expectations, and capital expenditure guidance came in below what some of the more anxious corners of Wall Street had feared. In an environment where the dominant fear was that AI infrastructure spending had become an unsustainable bubble, Microsoft essentially stood up and said: no, the demand is real, and we can fund it without blowing out free cash flow. The stock jumped roughly 16.4%, adding on the order of half a trillion dollars in market value in a single session — one of the largest one-day market cap gains by a single company in history.
Meta Platforms, which reported around the same time, told almost the opposite story. Revenue growth was healthy at roughly 22% year-over-year, but free cash flow collapsed by around 91% quarter-over-quarter as capital spending on AI infrastructure ballooned faster than the company could monetize it. Meta's stock fell about 9.2%. Put the two side by side and you get a genuinely useful natural experiment: the market wasn't punishing "AI spending" as a category. It was punishing AI spending that didn't come with a credible, near-term revenue story attached — and rewarding the company that could show both.
Two earnings reports, two completely different AI narratives. Source: company filings, Reuters, The Motley Fool.
Table 2 — Microsoft vs. Meta: Q2 FY2026 Scorecard
| Metric | Microsoft (MSFT) | Meta (META) |
|---|---|---|
| Stock reaction | +16.4% | -9.2% |
| Revenue growth (YoY) | ~+18% (overall); Azure ~+43% | ~+22% |
| Free cash flow change (QoQ) | Positive / above estimates | ~-91% |
| Market narrative | AI capex is paying for itself | AI capex is outrunning monetization |
4. Tracing the Transmission: From Redmond to Seoul in 24 Hours
What makes this week worth writing about, rather than just another volatile stretch for emerging markets, is how cleanly you can trace the cause and effect. It's rare to get a real-world case study this clean, so let's walk through it step by step.
The 24-hour chain reaction that turned Wall Street relief into a Korean market record. Source: Reuters, AP, The Motley Fool, Yonhap.
Microsoft's earnings landed after the US close on July 29. By July 30, the stock was up double digits and the broader Nasdaq had its best session in weeks, up roughly 2.6%, as chip and AI-infrastructure names across the board caught a bid. That relief carried directly into Asian trading on the morning of July 31 (Korea time). With Samsung Electronics and SK Hynix representing such an outsized share of the KOSPI, and with both stocks having been beaten down to what many desks considered oversold levels, the rebound in US tech sentiment gave Korean traders — foreign and domestic alike — a reason to step back in aggressively. Samsung closed up roughly 26.8%. SK Hynix closed up nearly 30%. The index itself closed up 17.91%, a record that, frankly, I hope stands for a very long time, because getting there involved a lot of pain for a lot of retail investors.
5. Meanwhile, at the Fed: Warsh's First Hawkish Revolt
Sandwiched right in the middle of this chaos was a Federal Reserve decision that, in a quieter week, would have been the biggest story in markets on its own. On July 29 — the same day KOSPI was hitting its intraday low — the FOMC voted 9-3 to hold the federal funds rate steady at 3.50%-3.75% for the fifth consecutive meeting. On the surface, a hold is a hold. But the composition of that vote is what caught my attention.
Three regional Fed presidents — Cleveland's Beth Hammack, Minneapolis's Neel Kashkari, and Dallas's Lorie Logan — dissented in favor of a 25-basis-point hike. A three-vote dissent at the Fed is genuinely unusual; it's the kind of split that tells you the committee's center of gravity is shifting even when the headline decision doesn't move. This was also only the second meeting under new Fed Chair Kevin Warsh, who has been deliberately stripping back forward guidance — his post-meeting statement was almost identical to June's, offering markets very little new information to trade on. Treasury yields moved regardless: the 10-year rose to roughly 4.657% and the 30-year climbed above 5.19% as traders concluded that a September hike is now a live possibility rather than a tail risk. The CME FedWatch tool had the odds of a hike at roughly 35% heading into the meeting; that number has only crept higher since.
A rare three-vote hawkish dissent under Chair Kevin Warsh. Source: Federal Reserve, CNBC.
I want to be direct about why this matters for Korea specifically: a Fed that hikes into September would strengthen the dollar, pressure the won, and make it harder for foreign capital to justify staying in a market that just delivered one of the most violent volatility episodes in its history. The KOSPI rebound and the Fed's hawkish undertone are, in a sense, pulling in opposite directions — and August will likely be about which force wins.
6. The Concentration Problem Nobody Fixed
Here's my honest, slightly grumpy take as someone who has watched this market for twenty years: nothing structural changed this week. Samsung Electronics and SK Hynix still account for more than half of KOSPI's total market capitalization. That concentration is exactly what turned an ordinary semiconductor correction into a historic monthly crash, and it is exactly what turned an ordinary earnings-driven relief rally into a record one-day gain. The same structural feature that makes KOSPI look terrifying on the way down makes it look euphoric on the way up. If you're an investor who prefers your index funds to actually behave like diversified baskets rather than leveraged bets on two chipmakers, this week should give you pause, regardless of how good the rebound felt.
7. SK Hynix and the HBM Backstop
One genuinely constructive data point from late July: on July 29, SK Hynix confirmed it had completed long-term supply agreements (LTAs) with more than ten customers for its HBM4 high-bandwidth memory chips, with full ramp-up expected in the second half of 2026. In an environment where China's memory-chip catch-up is the single biggest bear-case argument against Korean semiconductors, locked-in, multi-year customer commitments are about as close to a fundamental floor as this sector gets right now. It doesn't erase the volatility we just lived through, but it does suggest that the demand side of the AI memory story — as opposed to the trading and leverage side — remains intact. For readers tracking the broader HBM supply chain and the ongoing AI infrastructure buildout, I've covered the mechanics of that cycle in more depth here: SK Hynix's HBM4 Long-Term Contracts: Why They Matter More Than the Headlines.
8. What the Regulators Are Doing (Whether Korea Likes It or Not)
Korean financial authorities did not sit on their hands. Following the initial deposit-requirement hike on July 16 (raising the minimum deposit for single-stock leveraged ETFs from KRW 10 million to KRW 30 million), regulators convened an emergency market-stability meeting on July 29, led by Deputy Prime Minister and Finance Minister Koo Yun-cheol alongside Bank of Korea Governor Shin Hyun-song, Financial Services Commission Chairman Lee Eok-won, and Financial Supervisory Service Governor Lee Chan-jin. The headline outcome under discussion: a proposed 20% cap limiting how much of an individual investor's total portfolio can be allocated to single-stock leveraged ETFs, along with mandatory simulated-trading requirements before new investors can access these products, modeled partly on Hong Kong's flexible-leverage framework. It's a rare case of a regulator reacting to a volatility event within days rather than months, and it's worth watching closely if you have any exposure to Korean leveraged products specifically — as opposed to the underlying shares themselves, which are a different risk conversation entirely.
9. August Outlook: Two Roads Ahead
So where does this leave us heading into August? I see two genuinely plausible paths, and I don't think it's honest to pretend one is obviously more likely than the other yet — this is a market that just proved it can move 30+ percentage points in either direction within a matter of days.
What determines whether this week's rebound becomes a trend or a blip.
My own read, for what it's worth after twenty years of doing this: I lean cautiously constructive, but only on the fundamentals — not on the price action. Microsoft's and Meta's results genuinely clarified that AI capital spending is bifurcating into "spending that generates revenue" and "spending that doesn't," and SK Hynix's long-term contracts suggest Korea's memory makers are still on the right side of that line. That's a real, durable positive. But the mechanism that made this week so violent — extreme concentration in two stocks, amplified by leveraged retail products — hasn't been dismantled, only patched. I would treat the rebound as a genuine easing of the most acute AI-bubble fears, not as confirmation that Korean equity volatility is behind us. The September FOMC meeting, and whether Warsh's committee actually delivers the hike three of his colleagues just voted for, is likely to be the next real test.
10. Basic Investment Guidelines
I'll keep this section deliberately general, because anyone telling you exactly what to buy after a week like this either got lucky once or is selling something. A few basic, sensible starting points:
- Understand your actual exposure to Samsung Electronics and SK Hynix, whether direct, through KOSPI-tracking funds, or through sector ETFs — concentration risk doesn't disappear just because it's diversified across several fund wrappers.
- If you hold or are considering single-stock leveraged products, read the prospectus on daily rebalancing decay — these instruments are not designed to be held through multi-week volatility, and the 60% losses many July buyers experienced are a direct product of that structural feature, not just bad luck.
- Watch the September 15-16 FOMC meeting and Warsh's Jackson Hole remarks (August 27-29) for the next major directional catalyst on rates — and by extension, on the dollar-won exchange rate.
- Separate the "AI infrastructure demand" thesis (which July's earnings mostly reinforced) from the "Korean market leverage and concentration" thesis (which July's crash mostly exposed) — they are related but distinct risks.
For readers building out a broader view of the AI capex cycle and its knock-on effects across global markets, see also: The Real Cost of America's AI Power Crisis and What Warsh's Fed Is Deliberately Not Telling Markets.
This article is published for informational and analytical purposes only. Nothing contained herein constitutes financial, investment, legal, or tax advice. All investment decisions involve risk, including the possible loss of principal. Past performance is not indicative of future results. Readers should conduct their own research and consult a qualified financial advisor before making any investment decisions. The views expressed are solely those of the author based on publicly available information.
Sources
- Korea Exchange (KRX) — official trading data, July 2026
- Herald Corp / Herald Business — "코스피 '잔인한 7월'" and related coverage, July 29-30, 2026
- Segye Ilbo — leveraged ETF investor loss reporting, July 29, 2026
- Federal Reserve — FOMC Statement, July 29, 2026 (federalreserve.gov)
- CNBC — "Fed rate decision July 2026: Divided Fed holds interest rates steady"
- Fox Business — "July FOMC: Fed holds interest rates steady," July 29, 2026
- Advisor Perspectives (dshort) — "Fed's Interest Rate Decision: July 29, 2026"
- Reuters / The Motley Fool — Microsoft and Meta Q2 FY2026 earnings coverage, July 29-30, 2026
- Financial News (fnnews.com), Newspim, Newsway — Korean regulatory response coverage, July 29-31, 2026
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