The South Korean won rebounded sharply in July after months of mechanical selling linked to equity index rebalancing, with Bank of America reporting that the main source of forced outflows has now faded
The South Korean won (KRW) staged a significant recovery in July 2026, reversing earlier losses after a period of intense selling pressure tied to global equity index rules. According to a report from Bank of America, the mechanical outflows that had weighed on the won have largely run their course, allowing the currency to appreciate against the United States dollar (USD) and regain ground lost earlier in the year.
Throughout the first half of 2026, the won was among the weakest performing major currencies, as Korean equities experienced dramatic swings. The Kospi index surged to a record high, nearly quadrupling before undergoing a sharp correction that erased close to a third of its gains. This volatility triggered a wave of automatic selling by index-tracking funds, particularly when the market capitalizations of major companies like Samsung and SK Hynix exceeded the limits set by benchmark indices. As these firms grew too large relative to index caps, passive funds were required to trim their holdings, resulting in substantial outflows from both equities and the won.
Bank of America developed a regression model to analyze the relationship between rules-based selling, investor risk appetite, and currency movements. The model was able to explain about one-third of the daily swings in capital flows and closely tracked the cumulative outflows for the year, with a margin of error of roughly $5 billion. The forced selling was further amplified as global investors rebalanced away from Korea after its stock market outperformed other emerging markets, intensifying the downward pressure on the won.
By July, however, the mechanical drag from index-driven selling had diminished to nearly zero following the latest index review. With the main source of forced outflows exhausted, the won rallied by approximately 8% against the USD during the month, marking one of its strongest performances in recent years. This rebound coincided with a stabilization in Korean equity markets and a reduction in the country's overweight position in emerging-market indices.
According to Bank of America, the outlook for the won now depends less on mechanical index effects and more on broader market volatility. The final phase of outflows may hinge on the behavior of the VKOSPI, Korea's equity volatility index, which remains elevated. If volatility subsides, further stabilization of the won is possible, but renewed turbulence could trigger additional capital movement.
During July 2026, the South Korean won appreciated by around 8% against the United States dollar, reversing a period of underperformance earlier in the year. The Kospi index, after reaching a record high, corrected by nearly one-third, prompting index-tracking funds to sell both equities and won holdings. Bank of America's model estimated that rules-based selling accounted for about one-third of daily flow swings and tracked cumulative outflows to within $5 billion for the year.
Index-driven rebalancing is a recurring feature of global financial markets, especially in countries with large, concentrated equity sectors. When major companies exceed index weight limits, passive funds must adjust their portfolios, often resulting in significant capital flows that can affect both stock prices and currency values. While these mechanical effects can be powerful in the short term, they typically fade once rebalancing is complete, leaving broader market sentiment and volatility as the main drivers of currency direction.
