Buoyed by Nvidia's strong results and the ebbing of talk about an AI bubble, the KOSPI reclaimed the 4,000 mark. Foreign investors who had left amid jitters returned for bargain hunting, and expectations for semiconductors such as Samsung Electronics increased. However, the chances of a year-end rate cut by the US Federal Reserve have moved further away, and concerns over an AI bubble still linger, leaving room for sentiment to deteriorate.

On the day, the KOSPI closed at 4,004.85, up 75.34 points (1.92%) from the previous session, recapturing 4,000 after three trading days. Intraday, it rose as much as 129.86 points (3.31%) to 4,059.37. The KOSDAQ index also showed strength, ending at 891.94, up 20.62 points (2.37%) from the previous session.

Abroad, Taiwan's TAIEX finished up 3.18%, and Japan's Nikkei 225 at one point jumped more than 4% intraday, as stock markets at home and overseas cheered in unison on the back of Nvidia's earnings release.

On the 19th (local time), Nvidia announced revenue that exceeded market expectations ($57.01 billion) and guidance (Q4, $65 billion). Market optimism grew as Nvidia CEO Jensen Huang, who said that “Blackwell chip sales are poised to blow through the charts,” dismissed the AI bubble narrative by saying the AI industry is in a virtuous cycle.

Wall Street had projected Nvidia shares could move about 7% in either direction depending on the results, but including after-hours trading they climbed as much as 8% from the prior day, reversing the subdued mood.

Foreign investors were net buyers of 645.7 billion won in the KOSPI market on the day, and institutions bought a net 761.9 billion won, propelling the index. Samsung Electronics, the stock most heavily net-bought by foreigners (532.0 billion won), surged 4,100 won (4.25%) to finish at 100,600 won, returning to ‘100,000-won Samsung Electronics’ after three sessions. Shipbuilding and defense names, which had plunged under profit-taking pressure, also rebounded on bargain hunting.

SK hynix rebounded more than 6% intraday, touching 590,000 won, but heavy foreign net selling trimmed the gains. SK hynix closed at 571,000 won, up 9,000 won (1.6%) from the previous session.

Although talk of an AI bubble has subsided, uncertainty over US monetary policy has instead increased. Minutes of the October Federal Open Market Committee meeting released the same day indicated many at the Fed viewed holding the policy rate steady for the remainder of the year as appropriate, reducing the probability of a December rate cut to 32.8%.

Semiconductors surged on Nvidia's results, but the share prices of the big tech companies that drive AI investment and purchase chips saw gains capped by concerns over monetization. Optimism has grown, but investor sentiment could turn pessimistic at any time.

Lee Kyung-min, an analyst at Daishin Securities, said, “With AI tailwinds improving investment sentiment, the hawkish rate environment has been overshadowed,” adding, “to sustain the uptrend, it is necessary to watch for factors that could lead to foreign outflows.”