South Korea's benchmark Korea Composite Stock Price Index (KOSPI) was trading 48.32 points, or 0.69 percent, higher at 7,026.26 as of 11:20 am IST on Tuesday, 18 August, after opening the session with a sharp 2 percent gain that was quickly eroded by profit-taking. Fading hopes for a diplomatic resolution to the US-Iran conflict weighed on sentiment, capping what could have been a stronger rally.

What Drove the Early Surge

Tech heavyweights powered the initial advance. Market bellwether Samsung Electronics rose 0.46 percent, while chipmaking rival SK Hynix jumped 4.07 percent. Both counters had been under pressure in recent weeks over concerns about the profitability of artificial intelligence (AI)-related investment, and Tuesday's move reflected a partial recovery from that turbulence.

Refiner SK Innovation climbed 3.11 percent and shipping firm HMM surged 6.12 percent, adding to the broad-based early momentum.

Profit-Taking and Global Headwinds

Retail investors and institutions sold a net 804.7 billion won (approximately US$570 million) and 219.9 billion won worth of stocks, respectively, trimming the index's advance. Foreigners, however, were net buyers to the tune of 1.07 trillion won, providing a partial offset.

Overnight cues from Wall Street were mixed-to-negative. The Dow Jones Industrial Average shed 0.51 percent, while the tech-heavy Nasdaq Composite declined 0.32 percent. Elevated oil prices stoked inflation concerns, and prospects for a US-Iran deal dimmed further after US President Donald Trump indicated he was not interested in extending an agreement with Iran that was set to expire.

Notable Decliners

Not all sectors participated in the recovery. Top carmaker Hyundai Motor fell 1.77 percent, and defence giant Hanwha Aerospace declined 1.55 percent. The Korean won traded at 1,411.45 won against the US dollar as of 11:20 am, up 4.15 won from the previous session's close.

Margin Debt Climbs as Retail Confidence Returns

A notable undercurrent in the market is the sharp rise in margin lending. The amount of money borrowed to purchase stocks — known as margin debt — reached 30.93 trillion won (approximately US$21.8 billion) as of the previous Thursday, up from 27.44 trillion won on 3 August, according to data compiled by the Korea Financial Investment Association (KOFIA). The upturn signals renewed retail confidence as the market rebounds from its recent deep trough, though elevated leverage also raises the risk of amplified volatility should sentiment reverse. All eyes now turn to the trajectory of US-Iran negotiations and the next oil price move for direction.