[Nikkei Recap] Sep 4, 2026: Nikkei 225 Jumps 806 Points to 65,020 as SoftBank Group Surges 11.8% on AI Buy-Back

Hey everyone, Hirokichi here.

Tokyo stocks bounced back sharply today (September 4, 2026). The Nikkei 225 closed at 65,020.94, up 806.46 points (+1.25%) from the previous day, snapping a four-day losing streak and reclaiming the 65,000 level for the first time in three sessions. The rally was driven by a broad rebound in US tech and semiconductor stocks overnight, with SoftBank Group alone giving the index a huge lift. On the other hand, the yen strengthened, which weighed on export-related names like automakers. Let’s look at what happened today, why it happened, and which stocks were in the spotlight.

Today’s index moves

Here’s a summary of the major indexes at today’s close.

What this table shows is that while the Nikkei 225 and the Growth 250 Index rebounded strongly, TOPIX was essentially flat. SoftBank Group, a heavyweight stock (a stock with a high per-share price that has an outsized effect on the price-weighted Nikkei 225), surged and pulled the Nikkei up hard, but across the whole Tokyo Stock Exchange Prime market, advancing issues (788) and declining issues (712) were actually close to even. TOPIX is calculated based on market capitalization, so it reflects the broader market mood more closely than the Nikkei — which explains why it looked far less dramatic today. Trading value came in at about 8.33 trillion yen, on volume of roughly 2.21 billion shares (source: Wealth Advisor market report).

The Growth 250 Index also rose +2.67%, its first gain in five sessions, showing buying interest returning to the smaller-cap growth market too.

What moved the market today?

To understand today’s rally, we need to start with what happened in the US market the day before.

(1) A sharp US rally on September 3 (local time): The Dow Jones Industrial Average jumped 624 points to close at 53,686.11 (+1.17%). Fed Governor Waller softened his hawkish tone (a stance favoring rate hikes), which pulled long-term interest rates lower. That was welcomed by investors, and buying flowed back into tech, semiconductor, and AI-related names. This momentum carried straight through to Tokyo’s open today.

(2) SoftBank Group rode a rally in Arm shares: On September 3 local time, shares of Arm — the UK-based chip designer that is a SoftBank Group subsidiary — rose. That drew buying into SoftBank Group, which single-handedly gave the Nikkei 225 a massive boost (more on this below).

(3) A stronger yen weighed on exporters: At the same time, USD/JPY traded around 156.10, moving in a yen-strengthening direction from the prior session. A stronger yen tends to shrink the yen value of overseas earnings for exporters, so automaker stocks and other export-related names stayed soft all day. That currency tug-of-war is why the rally wasn’t across the board.

(4) Caution ahead of the US jobs report: The Nikkei briefly rose as much as 967.97 points to 65,182.45 in the afternoon session, but gains were capped by profit-taking as investors turned cautious ahead of the US August jobs report due out later on September 4 local time. That’s the reason the rally didn’t run further (source: Wealth Advisor market report).

Looking back over the last five trading days, the Nikkei fell for three straight sessions from the 66,300 level on August 31 down to the 64,200 range by September 3, and today it finally rebounded — recovering roughly half of that decline in a single day.

Today’s spotlight stocks, and why they moved

Here are four stocks that captured today’s market mood.

This table shows that AI and semiconductor names were the main story of the day, and that stocks that had rallied hard also saw sharp pullbacks. Let’s dig into each one.

SoftBank Group (9984): The single stock that lifted the Nikkei

Shares closed at ¥5,590, up ¥589, or +11.8% — a huge move. The trigger was a rally in shares of Arm, the UK chip designer that is a SoftBank Group subsidiary, on September 3 local time. SoftBank Group holds a large stake in Arm, so a rise in Arm’s share price directly boosts expectations for gains on that holding. Because the Nikkei 225 is a price-weighted index, expensive stocks like SoftBank Group have an outsized influence on the whole index, and at one point in the afternoon session it single-handedly pushed the Nikkei up as much as 967.97 points to 65,182.45. What made the move this big, in my view, is that the market already had underlying expectations around AI-related investment (data centers, OpenAI-related speculation), and the concrete Arm news landed right on top of that, triggering a rush of buying.

Taiyo Yuden (6976): Buying spread across electronic component makers

Shares closed at ¥9,426, up ¥569, or +6.4%. Electric appliance stocks (makers of electronic components and devices) were broadly strong today, and Taiyo Yuden rode that wave. As a maker of capacitors and other electronic components, Taiyo Yuden is seen by the market as a beneficiary of both smartphone/server demand and the broader expansion of AI-related capital spending. With US tech stocks rallying overnight, buying spilled over into domestic names that tend to move in tandem.

Kioxia Holdings (285A): Expectations for new AI technology

Shares closed at ¥54,460, up ¥2,790, or +5.4%. The move followed a technology briefing the company held on September 3, where it unveiled a new “CXL module” aimed at AI processing. This is designed to boost the performance of NAND flash memory (a type of memory chip used for data storage) so it can take over some of the role traditionally played by DRAM, doubling capacity and improving performance by about 30%, according to the company. This comes on top of a broader earnings recovery at Kioxia, driven by rising NAND prices — average selling prices reportedly rose about 70% quarter-on-quarter — amid growing AI-related investment. With both a technology story and an earnings story working together, it’s easy to see why the stock jumped more than 5%.

Tier IV (593A): Limit-down after a rapid run-up

Shares closed at ¥2,870, down ¥700, or -19.6%, hitting the daily limit down. This Growth Market-listed autonomous driving technology company had been on a rapid tear, hitting the daily limit up on consecutive days since around August 28. Today, buying interest in autonomous-driving names cooled off, and profit-taking from investors who had built up large gains during the run-up hit all at once, driving the stock to limit down. Stocks that multiply in price over a short period tend to see equally extreme moves on the way down — and today was a textbook example of that.

What this means for individual investors

For anyone doing regular index investing, an 800-point daily swing doesn’t really change the big picture. This week saw three straight down days followed by today’s rebound, but in my view, these short-term ups and downs are really just part of what makes dollar-cost averaging work — they’re simply “buy the dip” moments within a long-term plan.

For short-term traders, though, today’s action — money rushing into AI and semiconductor themes, with sharp pullbacks hitting the names that had rallied hardest — is a good reminder of both how popular a theme can get and how risky individual stocks within it can be. If you’re chasing a stock like Tier IV that has multiplied in a short window, it’s worth assuming profit-taking could hit at any time.

What to watch going forward

(1) The US August jobs report (due September 4 local time): This is the direct reason today’s rally didn’t run further. The result will shape expectations for Fed rate cuts, which should ripple into Tokyo trading next week.

(2) The USD/JPY level: Whether the yen keeps trading in a range around 156, or strengthens further, will continue to sway export-related stocks.

(3) AI-related names like SoftBank Group: Whether this kind of heavyweight-stock-led rally continues, or buying broadens out to a wider range of names, is worth watching for signs of how much staying power next week’s market has.

Let’s keep at it, slow and steady. See you tomorrow!

* This article is for informational purposes only and does not recommend any specific investment. Please make investment decisions at your own responsibility.

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You might also enjoy this earlier post about the Nikkei 225 hitting a post-bubble-era high.

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