The Index That Was Two Companies

1. The Bank of Korea hikes into a boom that lasted twelve days

On July 16 the Monetary Policy Board raised the base rate a quarter point to 2.75%, unanimously, its first increase in 42 months. Governor Shin Hyun-song declined to soften it: inflation would sit above target for a considerable period, financial risks were still there, and policy needed to keep a hiking stance. Nobody read that as a one-off. A central bank that had not moved since January 2023 was opening a cycle, and a good part of the case for opening it was a chip-led boom that had turned Korea into one of the best-performing equity markets on the planet.

Twelve days later that market gave up 16% in two sessions.

The currency is the one thing that has gone the way the Board wanted. The won has been the strongest major currency against the dollar this month, better than 6% up from July 1, trading near 1,460 after spending the spring at a 17-year low in real effective terms. Higher rates helped. So did a trade surplus fattened by exactly the memory exports now being repriced.

The read: Shin is holding a tightening stance whose only visible achievement is a firmer won, justified by a boom whose stock market has just handed back a year of gains inside a month. Which of those two was he actually aiming at?

2. Two companies trip the circuit breaker twice in 48 hours

Tuesday the Kospi fell 10.84% to close at 6,023.66, its fourth-largest single-day drop on record and the eighth circuit breaker of 2026. Wednesday opened up 1.09%, ran as high as 3.4%, turned around half past ten and was down 12.6% by early afternoon before closing at 5,663.24, off 5.98%. Trading halted on both the Kospi and the Kosdaq for a second straight day, which Korea Exchange had never done. Across the two sessions 864.5 trillion won of market value went away. On the month the index is down 32.5%, and it crossed 9,000 for the first time in its history only on June 18.

The trigger was SK Hynix. The company posted quarterly operating profit of 60.54 trillion won, up 557% on the year, on revenue of 79.32 trillion, at an operating margin of 76% that no memory maker has ever recorded. First-half revenue passed 100 trillion won for the first time. It was the best quarter in the firm's history and it landed 6.6% below what analysts had modelled, because the HBM4 ramp pushed revenue into the second half. The shares closed down 9.61%, and are off 46.7% in a month. Samsung, which reports in full on July 30, is down 35.5%.

Sunday's issue argued that an index falling because two firms missed is a verdict on two firms rather than on an economy, and that concentration is a governance problem on the way down. Korea has spent this week making the point at a scale the S&P 500 has never come close to. Samsung and SK Hynix are more than 40% of the Kospi's market capitalisation, which makes the national benchmark a leveraged position in two memory manufacturers wearing the costume of a diversified index.

The read: a company can print the most profitable quarter in its history and shed a tenth of its value the same day, because the price was never about the quarter. What exactly did people think they were buying at 9,000?

3. Koo Yun-cheol apologises for a product he approved in May

Wednesday evening Finance Minister Koo Yun-cheol convened an emergency meeting at six with Shin, FSC chairman Lee Eog-weon and Financial Supervisory Service governor Lee Chan-jin. Hours earlier he had sat in front of parliament and apologised for something more specific: the single-stock leveraged ETFs launched in May, products that track Samsung and SK Hynix at a multiple, which he conceded had reached the market without enough study beforehand. They sold out on listing.

They were not the only borrowed money in the building. Margin loan balances passed 60 trillion won in May, a record, concentrated in the same two names. By the middle of July more than 1.2 million leveraged retail accounts had been margin-called and somewhere between 320,000 and 360,000 were forcibly sold out. The Financial Services Commission has since banned new single-stock leveraged listings and raised margin requirements. Retail investors sold more than 2 trillion won net on Wednesday; institutions bought 2.4 trillion and could not hold the line.

The read: the leverage did not cause the repricing, it set the speed of it. A margin call is a seller with no opinion, and an index cleared out by margin calls is not telling anyone what memory chips are worth. Koo has apologised for the ETF. The harder question is who looked at a market where two stocks are 40% of the index and decided it could carry that much borrowed money.

The week ahead

• Samsung's full second quarter, July 30: preliminary guidance on July 7 pointed to roughly 89.4 trillion won of operating profit, which would be a third consecutive record. SK Hynix has just shown what the market now does with a record. Read the segment breakdown, not the headline.
• Whatever came out of Wednesday's six o'clock meeting: four regulators in a room after a two-day halt usually produces something. Watch whether the response addresses leverage or simply buys the index.
• The won against the equity market: the currency has been the best major performer this month while the stock market had its worst. One of those two is mispricing Korea, and August will start to say which.