TradingKey - On the first trading day of June, Japanese and South Korean stocks extended the AI boom, both hitting record highs. The Nikkei 225 index topped 67,000 points intraday for the first time, while South Korea's KOSPI index briefly broke through the 8,800 mark.
In the Japanese market, the Nikkei 225 index rose 0.91% to close at 66,934.11 points, having earlier breached the 67,000 threshold during the session.

[Source: TradingView]
Most notable was the dramatic shift in market capitalization rankings. SoftBank Group surged over 14% on the day, with its stock price hitting a new high of 8,541 yen and its market cap exceeding 48 trillion yen. It overtook Toyota Motor in the process, ending Toyota's more than 20-year reign as Japan's most valuable company. Toyota shares fell approximately 4.49% on the day.
A more than threefold increase in Arm's share price this year, combined with SoftBank's announcement of a 75-billion-euro investment to build an AI computing cluster in France, fueled the surge in SoftBank's stock. Semiconductor equipment manufacturer Tokyo Electron rose about 1.22%.
The South Korean market performance was even more aggressive, with the KOSPI index surging 3.68% to close at 8,788.38 points, a new record high; intraday gains exceeded 4.6% at one point, and KOSPI 200 index futures rose 5%, triggering a circuit breaker.

[Source: TradingView]
Among heavyweight stocks, Samsung Electronics closed up 10.09% at 349,000 won, with its market capitalization surpassing 2,000 trillion won and year-to-date gains reaching approximately 190%. SK Hynix rose 1.29% to 2,363,000 won, also hitting a record high.
LG Electronics hit the 30% daily limit for the second consecutive trading day, with its stock price reaching a new record high and year-to-date gains exceeding 310%. Markets anticipate LG Group Chairman Koo Kwang-mo will meet with NVIDIA CEO Jensen Huang on June 5 to discuss expanding cooperation in the field of physical AI.
On the macro level, South Korea's chip exports climbed to a record high of $37.2 billion in May. Jensen Huang's visit to South Korea later this week further boosted sentiment in AI-related sectors. Analysts believe the AI infrastructure investment boom and the global concentration of capital in the semiconductor sector are the core drivers of the sustained strength in Japanese and South Korean equity markets.