[Nikkei Recap] Sept 7, 2026: Nikkei 225 Jumps 1,378 Points to 66,399 as Chip Stocks Rally on Micron Production News

Hey everyone, Hirokichi here.

Tokyo stocks jumped on September 7, with the Nikkei 225 closing up 1,378.90 points (+2.12%) at 66,399.84, breaking back above the 66,000 line for the first time in four sessions. Semiconductor names led the charge after reports that Micron Technology plans to boost production of advanced memory chips, reigniting enthusiasm for anything AI-related. Friday’s U.S. jobs report came in far hotter than expected, which would normally be bad news for stocks — but on this Monday, Japanese investors clearly cared more about Micron than payrolls. Let’s walk through what moved and why.

How the indexes moved today

(Source: Nikkei Inc. market data, as of the 3:30 PM JST close on September 7, 2026)

As the table shows, the Nikkei and TOPIX both rose solidly, while the Growth 250 index — which tracks smaller, newer growth companies — actually fell. That’s a sign that large, high-priced semiconductor names pulled the headline index up while money flowed out of smaller growth stocks. The Nikkei Semiconductor Stock Index, which tracks chip-related names within the Nikkei 225, jumped +5.33%, far outpacing every other benchmark.

Looking back over the last five trading days, it’s been a “V-shape”: the Nikkei sank 1,889 points on September 2 as an Iran military strike pushed up oil prices and interest rates, kept falling through September 3, then rebounded for two straight sessions on the 4th and today.

Note that U.S. markets were closed on September 7 for Labor Day, so the most recent comparable U.S. session is Friday, September 4. The Dow fell 271.86 points to 53,414.25 (-0.51%), the S&P 500 dropped 29.11 points to 7,718.60 (-0.38%), and the Nasdaq Composite slipped 77.07 points to 26,506.99 (-0.28%) — all modest declines to close out the week (sources: Nikkei, Zaikei Shimbun, Bloomberg).

What moved the market — and why

There were two key drivers behind today’s rally.

(1) Reports that Micron Technology plans to increase production. Micron, one of the world’s largest memory chipmakers, was reported to be ramping up production capacity for advanced memory chips to meet growing AI-related demand. That reignited optimism about the broader AI market, and buying poured into Japan’s semiconductor-related names.

(2) The U.S. jobs report got shrugged off. Friday’s August employment report showed nonfarm payrolls up 162,000 — more than three times the 53,000 economists had expected. Normally, a number that strong would raise expectations for a Fed rate hike in September and weigh on stocks (and indeed, the Dow and S&P 500 both dipped slightly on the news Friday). But by Monday in Tokyo, the Micron story carried far more weight than the jobs data — as one Nikkei headline put it, “investors chose Micron over the jobs report.”

It’s also worth noting that the Growth 250 index fell even as trading value in the Prime Market segment surged to a high for the year — a sign that money rotated out of smaller growth names and into large-cap chip and AI plays for the day.

Today’s most talked-about stocks — and why they moved

The top gainers list was dominated by semiconductor and AI-related names.

(Source: Nikkei Inc. market data, September 7 close)

Every single one of today’s top gainers sits somewhere in the semiconductor supply chain. Let’s dig into a few.

SoftBank Group (9984) closed at ¥6,217, up 11.22% — the day’s biggest gainer. SoftBank is a major investor in OpenAI, and multiple reports suggest OpenAI is preparing for a possible IPO (initial public offering). On top of that, OpenAI CEO Sam Altman reportedly said on September 6 that “everyone should have their own personal robot,” signaling the company’s push into humanoid robotics. SoftBank Group tends to react sharply to any OpenAI-related headline given how central that stake is to its AI story. Some of today’s sharp move likely also reflects the stock having lagged recently, plus short-covering by margin traders (I couldn’t confirm the exact scale of that from the data available, so take it as market chatter rather than a hard fact).

Kioxia Holdings (285A) closed at ¥59,530, up 9.31%. Kioxia is the world’s third-largest maker of NAND flash memory. At first glance, Micron ramping up production might look like bad news for a competitor — more supply usually means lower prices. But many investors read it instead as a sign the entire memory market is set to expand, and money flowed into Kioxia as one of the biggest names in the space.

SAMCO (6387), MARUWA (5344), and Ibiden (4062) are all suppliers to the chip industry rather than chipmakers themselves. SAMCO makes semiconductor manufacturing equipment for compound semiconductors, MARUWA makes ceramic components used in chip packaging, and Ibiden is the top maker of IC package substrates. For all three, a Micron production increase means a direct hope for more orders — and each jumped 8-10% on the news.

Meanwhile, the day’s biggest losers were SaaS and growth names: Sansan (4443) fell 8.44%, Rakus (3923) fell 7.45%, Money Forward (3994) fell 7.29%, and SHIFT (3697) fell 5.91%. As money piled into a single AI-semiconductor theme, it had to come from somewhere — and that “somewhere” was the growth stocks that had been in favor recently. The Growth 250 index closing lower confirms this rotation.

What this means if you’re an individual investor

If you’re mostly holding index funds through regular contributions, a day like today — where the rally is driven by a narrow set of theme stocks — shouldn’t move your net asset value all that much. TOPIX only rose 0.55%, a much smaller gain than the Nikkei’s 2.12%, which tells you the broader market didn’t move nearly as much as the headline number suggests. I think it’s fine to just keep contributing steadily.

If you hold individual semiconductor or growth stocks, though, today was a reminder of how volatile this market can be. A single overseas headline — like Micron’s production plans — can send a whole basket of related Japanese stocks up 9-10% in a day. Chasing a move like that after it’s already happened often means buying at the top. I’d rather wait and see how the story develops over the following days than trade on the headline itself.

What to watch next

(1) How U.S. markets react. U.S. markets reopen on September 8 after the Labor Day holiday, so it’ll be worth watching how American semiconductor stocks respond to both the Micron news and today’s rally in Tokyo.

(2) Rate-hike expectations ahead of the September FOMC. With expectations for a Fed rate hike building after Friday’s jobs report, upcoming economic data could easily become a headwind for stocks again.

(3) Whether the rotation out of growth stocks continues. Today’s move was a clear shift toward AI and semiconductors — whether that’s a one-day event or the start of a longer trend is worth watching in the Growth 250 index going forward.

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.

The previous session’s recap (Sept 4) is here → [Nikkei Recap] Sep 4, 2026: Nikkei 225 Jumps 806 Points to 65,020 as SoftBank Group Surges 11.8% on AI Buy-Back

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