Chipmaker-led KOSPI rally raises questions about broader investor benefits

An electronic signboard at the Hana Bank dealing room in Seoul displays the benchmark KOSPI closing at 3,472.14 points on Wednesday, down 14.05 points, or 0.4 percent, from the previous session. Yonhap

The benchmark KOSPI is on a record-breaking rally, but whether the gains are broadly benefiting investors remains uncertain, as more than one-third of the gains are driven by just Samsung Electronics and SK hynix, analysts said Wednesday.

Since Sept. 15, the main index has largely closed above the 3,400-point mark — a level it had never previously reached — after breaking a record that held for more than four years with a close of 3,314.53 on Sept. 10.

Notably, KOSPI recorded back-to-back all-time closing highs earlier this week, ending at 3,468.65 on Monday and 3,486.19 on Tuesday, before slipping 0.4 percent to 3,472.14 on Wednesday.

According to Korea Exchange (KRX) data, KOSPI rose 52.6 percent as of Monday from its 52-week intraday low of 2,284.72 on April 9, which was caused by concerns over tariffs imposed by the U.S. government on Korean imports.

Over the same period, the total market capitalization of roughly 830 KOSPI-listed companies rose by 975.31 trillion won ($698.45 billion), from 1,880.17 trillion won to 2,855.48 trillion won.

“But such impressive gains can be misleading and even illusory, as they are largely driven by just Samsung Electronics and SK hynix,” Jung Eui-jung, head of the Korean Stockholders’ Alliance, said.

The two chipmakers currently rank first and second by market capitalization.

KRX data showed that Samsung Electronics contributed 20.4 percent of KOSPI’s 975.31 trillion won increase in market cap, while SK hynix accounted for 13.9 percent. Combined, the two made up 34.3 percent of the gains.

That figure rises to nearly 40 percent when counting affiliated companies tied to their corporate governance structures, including Samsung Life Insurance, Samsung C&T and SK Square.

Jung pointed out that other leading firms made only limited contributions to the rally, with Doosan Enerbility accounting for 2.8 percent, Hanwha Aerospace with 2.2 percent, HD Hyundai Heavy Industries at 1.9 percent and KB Financial Group with 1.7 percent.

Foreign capital inflows have also been disproportionately concentrated on the two semiconductor giants.

While foreign investors have returned to net buying in the KOSPI market this year, their net purchases as of Monday amounted to 3.61 trillion won in SK hynix and 2.43 trillion won in Samsung Electronics.

Excluding those two, foreign investors remain net sellers of more than 6 trillion won.

As a result, even as KOSPI hits new highs, portfolios without Samsung or SK hynix have underperformed or even declined in value.

For example, Doosan Enerbility has fallen more than 10 percent from recent highs, while HD Hyundai Heavy Industries and KB Financial Group are both down by nearly 8 percent.

Lee Soo-jung, a researcher at Meritz Securities, predicted that the current KOSPI gains led by the two chipmakers “may continue for some time.”

She pointed out that average selling prices of dynamic random access memory and NAND flash are predicted to rise by 24.8 percent and 22.9 percent, respectively, from 2025 to 2026.

The figures represent upward revisions of 9.3 and 5.8 percentage points from previous estimates.