Blue chips lead market higher despite Trump's expletive-laden threats on Iran

A display board in the dealing room at Hana Bank headquarters in central Seoul shows the won-dollar exchange rate, along with the KOSPI and Kosdaq indexes, Monday. The benchmark KOSPI closed at 5,450.33, up 1.36 percent from the previous session. Yonhap

Korea's benchmark KOSPI closed higher Monday, supported by institutional buying and gains in major tech shares, despite lingering uncertainty in the Middle East following U.S. President Donald Trump's escalating threats toward Iran.

Investors positioned ahead of Samsung Electronics' preliminary earnings for the first quarter set for Tuesday, helping lift overall market sentiment.

The KOSPI opened at 5,423.35, up 46.05 points, or 0.86 percent, from the previous session. It traded around the 5,430 level before briefly climbing above 5,500 at around 11:20 a.m., and closed at 5,450.33, up 1.36 percent.

Institutional investors bought a net 837.1 billion won ($555.5 million), leading the market higher. Retail and foreign investors sold a net 1.05 trillion won and 156.3 billion won, respectively.

Market bellwethers traded higher.

Samsung Electronics rose 3.71 percent to 193,100 won ahead of its preliminary earnings release scheduled for Tuesday, with some market watchers expecting operating profit to surpass 40 trillion won for the first time on strong demand for premium memory chips. SK hynix gained 1.14 percent to 886,000 won.

The secondary bourse Kosdaq opened at 1,068.33, up 4.58 points, or 0.43 percent, from the previous session's closing, but later reversed course to close at 1,047.37, down 1.54 percent.

In the foreign exchange market, the Korean won opened at 1,510.3 per dollar, down 5.1 won from the previous session, and ended at 1,506.3 won.

Despite the KOSPI's ascent, investor sentiment largely remained cautious, with markets bracing for a volatile week after Trump warned that Tehran would be "living in hell" if it fails to reopen the Strait of Hormuz.

In an expletive-laden social media post on Easter Sunday, Trump doubled down on threats to devastate Iran's power plants and bridges if Tehran does not end its blockade of the key waterway.

Hours later, the U.S. president appeared to extend his initial Monday deadline for a deal by one day, saying only: "Tuesday, 8:00 p.m. Eastern Time!"

Iran showed no signs of backing down, despite Trump's ultimatum, warning that it could disrupt trade on the Bab el-Mandeb, a key chokepoint in the Red Sea.

NH Investment & Securities projected the KOSPI will move in a range of 5,000 to 5,700 this week, while Kiwoom Securities forecast a range of 5,050 to 5,650.

"Trump's hard-line rhetoric on Iran has deepened market caution. Investors' expectations for Samsung Electronics' preliminary earnings helped support equities," said Kang Jin-hyuk, an analyst at Shinhan Securities.

Oil prices extended gains amid escalating tensions in Iran. U.S. West Texas Intermediate crude hovered around $111 per barrel, while Brent crude traded near $109. Dubai crude, which accounts for about 80 percent of Korea's oil imports, stood at around $114 per barrel.