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KOSPI Rises 2.66% on Semiconductor Strength

By Stocks Desk · 2026-09-18 · 1 min read
A close-up view of a silicon wafer with a grid of square chips.
Illustration: Tradingbird

Samsung Electronics and SK hynix led a sharp market rally as foreign and institutional investors returned to net buying positions.

The KOSPI index closed at 6,894.23 on September 18, marking a gain of 178.82 points or 2.66%. This significant upward movement placed the benchmark index within reach of the 6,900 threshold. The rally was primarily driven by robust performance in the technology sector, specifically semiconductor heavyweights, amid improving industry outlooks.

Investor sentiment shifted decisively toward risk assets, with foreign and institutional buyers driving the session. Foreign investors recorded net purchases of 420.6 billion won, their first net buying streak in eight trading days. Institutions added 3.1675 trillion won to their positions, while individual investors exited the market with net sales of 3.5881 trillion won to lock in profits.

Semiconductor Leaders Drive Index Gains

Samsung Electronics finished trading at 261,000 won, up 3.37% from the previous session. SK hynix outperformed its peer, closing at 1,867,000 won, a 6.42% increase. Both stocks benefited from concentrated buying activity by foreign and institutional investors, contributing significantly to the KRX Semiconductor Index gains.

The strength in semiconductors extended to the broader electronics sector, which moved in tandem with the index. While capital focused on tech leaders, other major market-cap stocks like LG Energy Solution, Hyundai Motor, and Kia remained relatively flat. Biopharmaceutical names Samsung Biologics and Celltrion also posted modest gains, supported by institutional demand.

KOSDAQ and Exchange Rate Trends

The KOSDAQ index closed at 827.12, rising 0.60% for the day. In this market segment, individual and institutional investors net bought 12 billion won and 22.3 billion won respectively, while foreign investors net sold 33.8 billion won. Top KOSDAQ firms in biotechnology and battery materials generally maintained an upward trajectory.

In the foreign exchange market, the won/dollar rate closed at 1,383.3 won, a slight depreciation of 1.1 won from the previous session. This marked the seventh consecutive trading day of upward movement for the dollar. Despite significant inflows into the stock market, the exchange rate remained stable within the low 1,380 won range, according to GN stocks/chips reporting.

Based on reporting by Businesskorea, compiled by the Tradingbird desk.

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