Bank worker Yongjoon Kim lost 20 million Korean won ($14,000; £10,500) on the South Korean stock market last month.

Kim's money was meant to help buy a home, as he is getting married later this year.

Instead the value of his tech investments slumped by around 25% in July.

"It's going to sting and I'm going to have to work really hard to make up for this," Kim says. "But for others who have taken more risk, they're going to feel the pain."

Many of his friends are worse off, and now in a "desperate" situation after "going all in" with their savings, he says.

While plenty of investors are piling into technology stocks, sharp market swings mean the bets don't always pay off, with prices often moving on every major headline.

Nowhere is that instability more pronounced than in South Korea's tech-heavy Kospi, widely regarded as the world's most volatile stock index.

A global frenzy around artificial intelligence has driven wild swings in the value of the country's biggest chipmakers.

The Kospi faced "one of the sharpest corrections" in its history between June and August, comparable to the drops seen during Covid-19 and the 1997 Asian financial crisis, says Wee Khoon Chong from financial services company BNY.

The index more than doubled its value since the start of the year to rise above 9,000 points in mid-June, before plunging to 5,500 within a few weeks. It has now recovered some ground to about 6,800 points.

A key reason for the sell-off in recent weeks has been concerns over the huge amounts of money being spent on AI, Chong adds.

The slump has had a big impact on many of the country's personal investors who bought tech stocks over the past year.

For Woongsa Kim, a look at his shares trading app is a painful reminder of what he had made then lost by investing in the South Korean stock market.

At the start of the year, he used about half of a bonus from work to buy shares in tech giant SK Hynix.

The stock quadrupled in value before most of those gains were wiped out, leaving his investment, now worth about 300 million won, at roughly half the value of its peak.

"Thinking about it just brings tears to my eyes," Kim told the BBC.

The sell-off came after tech shares had soared for months, "generating the extreme euphoria" that has moved some personal investors to take out loans to invest, says investment analyst Tobias Reger.

It has been most acutely felt by people who used leverage - a form of borrowing in the financial markets.

Leveraging lets an investor control a larger number of stocks than their own cash would otherwise allow, which delivers a bigger profit if the shares rise.

However, if the stocks fall past an agreed level it can trigger what is known as a margin call - when a broker demands payment of the debt.

By the end of July an estimated 1.2 million South Korean personal investor accounts had faced margin calls, equivalent to about one in every 30 working-age adults in the country.

Leveraged trading is a growing trend among personal investors that has also picked up in markets like Taiwan and the US, says Frank Benzimra, the head of Asia equity strategy at financial services group Societe Generale.

That has raised the risks around AI-related stocks, he adds.

After his US-listed Nvidia shares soared by more than 1,000%, Chanyong Park, who works in marketing, says he put most of the profits into SK Hynix shares. But that bet went sour as their value has fallen by around $10,000.

"This was money I'd invested to save before planning to leave my job around October to start my own business. But now I'm seriously wondering whether I'll have enough."

Park plans to hold on to his SK Hynix shares in hopes of a rebound, although recent swings have made him hesitant to invest more.

"It doesn't always feel like movements are driven by rational reasons - sometimes it still feels a lot like gambling," he says.

Another investor Youngji Park says he went "all in", putting the majority of his available cash into Samsung shares that peaked at a total value of 45 million Korean won.

But his investment has suffered a "gut-wrenching" slump, Park says.

He too plans to keep hold of his shares in the hope that they will rise again.

"I feel like a fool for trusting the Korean stock market," he says. "It's a long-term game now. I'll just have to wait it out."

College student Soomin Yi says she pooled money with a friend to invest in SK Hynix after experiencing "fomo" (fear of missing out).

But she now wishes she had sold her shares in the company when they peaked at three million won each in June, instead of buying into speculation that they would rise to five million won.

"We didn't really have anyone around us who is experienced in investing, and we did not study investing seriously before buying the stock," Yi says.

The huge swings in Korean shares are also raising concerns about some other markets around the world.

Tech-heavy indexes like Japan's Nikkei 225 seem to be moving in tandem with the Kospi's wild swings, Societe Generale's Benzimra says.

But the majority of the world's stock markets are unlikely to see that level of violent moves as they include a wider mix of companies, he adds.

"I don't think we can see the same kind of volatility in large diversified markets such as the [Tokyo Stock Price Index] or the US equity markets," Benzimra says.

And traders who diversified their portfolios say it has helped cushion the blow from the stock market rout.

"I think this whole episode is a warning to Korean investors, especially young investors, not to put everything in one basket and hope for the best," says Yongjoon Kim, who also has shares in overseas markets.

He adds that he should have taken a more cautious approach to investing in tech stocks.

His fiancée, Gaeon Lee, is optimistic that the market will recover despite losing part of the savings they had set aside for a new home.

But she worries about Kim, saying the constant need to monitor their investments has taken a toll on him. (BBC)

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