South Korea's KOSPI index rose 5.2% [1] to close at 8,545 [1] on Monday following news of a cease-fire agreement between the U.S. and Iran.

The surge reflects a rapid shift in investor sentiment as geopolitical tensions ease. This stability typically encourages foreign and institutional investors to return to emerging markets, particularly in high-growth sectors like semiconductors.

During the trading session, the KOSPI briefly topped 8,600 [1]. The momentum was strong enough to trigger a buying-sidecar, a volatility control mechanism used by the Korea Exchange. This marks the 14th [1] time such a mechanism has been activated this year.

Technology stocks drove much of the day's growth. Samsung Electronics shares rose 4.5% [1], while SK Hynix saw a sharper increase of 6.42% [1]. These two companies represent a significant portion of the index's total weight, meaning their performance heavily influences the overall market direction.

Market analysts said that the rally was fueled by aggressive buying from both foreign and institutional investors. The sudden influx of capital followed the reports of the diplomatic agreement, which reduced the risk of regional conflict, and supply chain disruptions.

"The KOSPI finished today's trading at 8,545, up 5.2% from the previous session," a YTN reporter said [1]. The reporter also said that Samsung Electronics and SK Hynix closed up 4.5% and 6.42% respectively [1].

“The KOSPI briefly topped 8,600”

The KOSPI's sensitivity to the U.S.-Iran agreement underscores the deep interconnection between Middle Eastern stability and East Asian markets. Because South Korea relies heavily on energy imports and global semiconductor exports, the removal of geopolitical risk triggers immediate capital inflows. The activation of a buying-sidecar indicates an atypical level of volatility, suggesting that investors were reacting to a significant perceived shift in global risk profiles.