South Korea's stock market downturn is undermining government efforts to keep retail investors, known as the "ant army," focused on domestic stocks, driving them to pour money into US equities at the fastest pace in six months and reigniting concerns about pressure on the Korean won.

Data from the Korea Securities Depository shows that in July, as the benchmark KOSPI index suffered its steepest monthly decline since the 2008 global financial crisis, Korean retail investors purchased $4.6 billion worth of US stocks. This figure significantly surpasses the 2025 monthly average of $2.7 billion. Notably, the total volume of Korean retail investments in US stocks for 2025 has already more than tripled from the previous year.

The data indicates that in July, Korean retail buying of US stocks exceeded their domestic stock investments for the first time since February, highlighting a rapid erosion of confidence in the local market. Analysts suggest this reversal could reactivate the multi-year trend of Korean retail capital flowing overseas, thereby weighing on the won and posing challenges for policymakers trying to broaden domestic capital market participation.

The KOSPI's slump is diminishing the appeal of the local market. Korean small-scale retail investors, referred to locally as "ants" due to their collective behavior, have historically favored the US market over domestic stocks, which are heavily tied to the performance of export-oriented giants in electronics, shipbuilding, and manufacturing. However, this trend shifted temporarily in recent months. As the KOSPI rallied, retail funds flowed heavily into Korean stocks, driven by the AI boom and government tax incentives encouraging the sale of overseas stocks to buy domestic ones. The government's multi-year push for corporate governance reforms to enhance shareholder returns also attracted retail investors.

But the recent sharp sell-off in the Korean market has worn down retail patience. Amid concerns over the sustainability of the AI investment frenzy and competitive pressures from Chinese rivals, the KOSPI has dropped 33% from its June peak. Chip behemoths Samsung Electronics and SK Hynix, which dominate the benchmark index, have accounted for approximately 76% of the decline, wiping out 2,257.8 trillion won (about $1.59 trillion) in market value. Actively traded leveraged exchange-traded funds (ETFs) linked to chip stocks have also amplified volatility. In contrast, the Nasdaq index remained largely stable over the same period.

"Capital outflows slowed when the domestic stock market was strong, but with the KOSPI crash, outflows have accelerated again, reinforcing the view among investors that the US market is the right choice," said Kwon Ah-min, a foreign exchange analyst at NH Investment Securities in Seoul. "They have grown tired of the Korean domestic market."

The strengthening of the Korean won has further fueled overseas investments by retail traders. In July, the won appreciated 8% against the US dollar, reaching a nine-month high and posting its best monthly performance since November 2022. This was partly driven by SK Hynix's $26.5 billion US listing, which brought some funds back to Korea. However, the stronger won reduces the incentive for investors to repatriate overseas asset funds and may stimulate new purchases of foreign assets, especially as investors anticipate that the US interest rate environment will continue to support the dollar.

According to the Korea Financial Investment Association, the "repatriation investment account" launched by the government in March to encourage capital inflows via tax breaks saw its first monthly decline in deposits during July. While some funds are flowing into funds holding Korean assets—such as $319 million into the Direxion Daily MSCI South Korea Bull 3X ETF last month—a larger volume is moving toward US stocks and funds focused on the US market. In August alone, as US stocks hit new highs and the KOSPI remained volatile, Korean retail investors have already net purchased $278 million in overseas stocks.

Meanwhile, the balance of domestic stock trading account deposits, a measure of local stock demand, fell to 102.8 trillion won as of Monday, the lowest level since mid-February and well below the all-time high of 140 trillion won recorded in early June, according to the Korea Financial Investment Association.

"If the Korean stock market continues to underperform the US market, we worry that the outflow of domestic retail capital could recur," analysts at Bank of America wrote in a report. "In other words, there is very limited room to create a stable portfolio flow environment conducive to the won's sustained appreciation."