For more than a year, South Korea had the most exciting stock market on earth. Money poured in, prices only seemed to travel in one direction, and a country long dismissed by investors as perennially cheap suddenly looked like the great growth story of the age. Then, in the space of a few weeks, the whole edifice came down. What had been the envy of global markets is now the site of one of the fastest collapses in modern financial history.
The scale of the preceding boom explains the violence of the bust. From the spring of last year to its peak in June, the benchmark KOSPI index surged by close to 300 percent, its strongest run since the legendary bull market of the 1980s. At its height the index touched a record above 9,385, and for a brief, giddy moment South Korea ranked as the sixth largest equity market in the world. Investors spoke of a mad bull, and for a while the label felt like a boast rather than a warning.
Built on borrowed money
Underneath the rally sat a structure that looked sturdy only while prices rose. This was a boom powered less by pension funds and foreign institutions than by ordinary Koreans, millions of whom threw themselves into the market with a fervour that unsettled even the optimists. They did not simply buy shares. They bought leverage, borrowing to amplify their bets and crowding into risky products that magnified the swings of individual stocks.
The favourite vehicles were single stock exchange traded funds tied to the country's two chip champions, Samsung Electronics and SK Hynix, the companies whose memory chips sit at the heart of the artificial intelligence boom. By early July the value of outstanding leveraged positions had swelled to a record 29.2 trillion won, close to 20 billion dollars. It was a wager, repeated a million times over, that Korea's grip on the world's most important technology was unbreakable and that the only direction left was up.
A blow from Beijing
The unbreakable assumption broke on July 28. Word arrived that China had begun mass producing its own deep ultraviolet machines, the intricate tools used to etch advanced chips, a capability that had until then belonged to a tiny club of foreign suppliers. For a market whose entire thesis rested on Korean dominance of the chip supply chain, the news landed like a hammer. If Beijing could build the machines itself, the moat that justified so many of those leveraged bets suddenly looked a great deal shallower.






