On September 23, Samsung Electronics and SK Hynix closed higher side-by-side on the eve of the Chuseok holiday. The investment sentiment was heavily supported by overnight strength in U.S. artificial intelligence (AI) and semiconductor stocks, along with expanding demand for memory and expectations for shareholder returns.

At the main bourse, Samsung Electronics finished the session up 3.25% at 285,500 won. After opening 2.89% higher at 284,500 won, the stock temporarily pared gains down to 281,000 won during intraday trading before regaining upward momentum in the afternoon.

SK Hynix also closed up 1.20% at 1,862,000 won. Early in the session, it touched 190 million won, marking a 3.26% surge, but later gave up a portion of those gains.

The strength of U.S. semiconductor shares spilled over into the domestic market. On September 22 (local time), Micron rose 5.00%, Nvidia added 0.66%, and the Philadelphia Semiconductor Index advanced 2.06%. Declining international oil prices and U.S. Treasury yields, combined with optimism over Meta’s AI agent 'Muse' and forecasts of increased server DRAM demand, stimulated semiconductor investment sentiment. Furthermore, SK Hynix American Depositary Receipts (ADRs) finished up 3.45% at $195.37.

Attention was also drawn to the recent inclusion of SK Hynix ADRs into the iShares Semiconductor ETF (SOXX), which tracks the NYSE Semiconductor Index (ICESEMI). Just two months after listing on the U.S. market in July, the inclusion weight of SK Hynix ADRs in SOXX is known to be around 3.3%.

For Samsung Electronics, dividend expectations served as an additional factor driving up share prices. Last month, the company finalized a shareholder return plan valued between 90 trillion and 110 trillion won, deciding to execute approximately 30 trillion won of it as third-quarter cash dividends. The record date for the Q3 dividend is set for the 30th.

However, profit-taking emerged across the broader market ahead of the Chuseok holiday. On the KOSPI market, retail and foreign investors net sold 1,439.6 billion won and 504.7 billion won, respectively, while institutional investors net bought 316.9 billion won.

Foreign trading directions diverged regarding large semiconductor stocks. Foreigners net bought 1,282.7 billion won worth of Samsung Electronics, making it the top net-bought stock, whereas they net sold 1,202.2 billion won worth of SK Hynix.

As treasury stock repurchases by Samsung Electronics and SK Hynix are currently underway, other corporations net bought 1,622.4 billion won in the electrical and electronic sector. Samsung has been purchasing 15 trillion won worth of treasury shares since last month, while SK Hynix plans to buy back 40 trillion won worth of treasury stocks and incinerate them in full.