[Anchor]

On the first trading day after the holiday, the KOSPI plunged nearly 4%, falling back to the 6,300 level for the first time in two months. Despite Samsung Electronics announcing record-breaking earnings, selling pressure from foreign investors continued.

Reporter Min Gyeongho has the details.

[Reporter]

Starting the session down more than 0.7%, the KOSPI failed to gain momentum throughout the day, surrendering even the 6,400 line.

It marked the steepest daily drop in about a month at -3.65%.

Foreign investors drove the market decline by net selling approximately 2 trillion won, while institutions also offloaded about 110 billion won.

Only individual investors remained net buyers, purchasing nearly 1.5 trillion won.

The direct trigger is attributed to a 3.8% drop in the Philadelphia Semiconductor Index, a stock indicator for U.S. semiconductor companies, while South Korean markets were closed for Hangeul Day.

Controversy over overheated investment reignited after OpenAI's revenue came in lower than expected.

Although it was later revealed to be due to differences in accounting aggregation methods, investor sentiment failed to recover, with Samsung Electronics and SK Hynix both recording declines in the 4% range.

Analysts say investors reacted more sensitively to negative news after witnessing stock prices fall even following Samsung Electronics' record-high earnings announcement last week.

[Lee Jin-woo / Head of Research, Meritz Securities: When sentiment is poor, people only see the negative aspects. As the justification for an upward move weakens, the market is taking on a clear characteristic of drifting downward due to supply and demand.]

Supply-and-demand factors, such as consecutive selling by foreign investors and the completion of treasury stock buybacks by semiconductor companies, are also having a significant impact.

Samsung Electronics announced that it completed its treasury stock buyback worth approximately 15 trillion won, which began last August for employee stock compensation, on the 6th.

SK Hynix is also in the final stages of wrapping up its treasury stock buybacks.

[Kim Dong-won / Head of Research, KB Securities: Since earnings conference calls for Samsung Electronics and SK Hynix are scheduled for late October, and major U.S. tech companies are also set to release their quarterly earnings, the stance is to wait and see until then.]

As companies sold off dollars earned from strong exports in sectors like semiconductors, the won-dollar exchange rate hit a two-year low, touching the 1,320 won range at one point in the afternoon.

(Reported by Lee Moo-jin | Video edited by Ahn Yeo-jin)