The stock-based wealth of South Korea's leading chaebol group heads suffered a significant decline during the third quarter of 2026, reflecting a sharp change in the value of their listed-company holdings.

According to an analysis by the Korea CXO Research Institute, the combined stock valuation of 48 major conglomerate chiefs stood at 115.44 trillion won ($80 billion) at the end of September, down from 134.02 trillion won at the end of June.

That represents a decline of approximately 18.58 trillion won, or 13.9%, in just three months.

The results were mixed across the group. While stock wealth increased for 25 business leaders, it declined for 23. However, the total decline among those 23 leaders reached around 22 trillion won, significantly outweighing the roughly 3.43 trillion won increase recorded by the 25 gainers.

The largest losses were concentrated among the leaders of South Korea's three biggest business groups by assets.

Samsung Electronics Chairman Lee Jae-yong recorded the biggest decline. His stock valuation fell from approximately 59.19 trillion won to 45.99 trillion won, a decrease of 13.20 trillion won, or 22.3%.

SK Group Chairman Chey Tae-won's stock wealth declined from 10.83 trillion won to 7.64 trillion won, representing a drop of about 3.19 trillion won.

Meanwhile, Hyundai Motor Group Chairman Chung Eui-sun saw his stock valuation fall from 7.76 trillion won to 6.58 trillion won, a decline of around 1.18 trillion won, or 15.2%.

Combined, the three business leaders lost approximately 17.57 trillion won in stock wealth during the quarter.

Despite the decline, Lee Jae-yong remained South Korea's richest conglomerate chief by listed-stock holdings at the end of September, followed by Celltrion's Seo Jeong-jin and SK's Chey Tae-won.

One of the biggest exceptions to the downturn was Celltrion Group Chairman Seo Jeong-jin.

His stock valuation increased from 11.89 trillion won at the end of June to 12.93 trillion won at the end of September. The 1.04 trillion won increase, equivalent to 8.7%, was the largest absolute gain among the 48 business leaders.

Interestingly, the increase was not primarily driven by Celltrion's share-price performance. The company's stock price rose only around 2.5% during the period, while Seo's holdings increased by roughly 6%, making the increase in his number of shares a major factor behind the higher valuation.

Huh Chang-soo, honorary chairman of GS Group, recorded the largest percentage increase.

His stock wealth jumped from approximately 415.8 billion won to 638.5 billion won, representing a 53.6% increase.

The rise was linked to strong gains in shares of GS and GS Engineering & Construction, which increased substantially during the quarter.

At the other end of the spectrum, Lee Woong-yeol, honorary chairman of Kolon Group, experienced one of the steepest percentage declines. His stock valuation fell from 650 billion won to around 252.4 billion won, a drop of 61.2%.

The latest figures highlight how strongly the fortunes of South Korea's major business leaders remain tied to stock market performance and listed-company valuations.

Because many conglomerate founders and family members hold substantial stakes in publicly traded companies, changes in share prices can produce enormous swings in their reported wealth within a single quarter.

The third-quarter figures also show that the decline was not universal. Several executives increased their stock holdings or benefited from stronger share performance, even as the combined valuation across the 48 leaders dropped sharply.

As of the end of September, 17 conglomerate chiefs had stock holdings valued above 1 trillion won, one more than at the end of June. DB Group founder Kim Joon-ki entered the so-called trillion-won club during the quarter.

The latest stock wealth figures provide a snapshot of the changing fortunes of South Korea's corporate elite.

While Samsung's Lee Jae-yong continues to hold the top position by listed stock wealth, the scale of his third-quarter decline was substantially larger than that of other major conglomerate leaders.

At the same time, gains at companies such as Celltrion and GS demonstrate that the country's billionaire landscape can change rapidly with movements in share prices and changes in ownership.

The figures are therefore not a measure of total personal wealth, but rather an assessment of the market value of the listed shares held by the country's major business-group chiefs.