A Huge Headline Number, a Narrow Tape
The Nikkei 225 closed Thursday, October 1, at 68,956.72, up 3.30% — one of those sessions where the index tells only half the story. The fuel was unambiguous: Micron Technology’s fiscal Q4 report, released after the U.S. close, delivered record quarterly revenue of $54.23 billion, GAAP net income of $37.70 billion, and fiscal Q1 2027 revenue guidance of roughly $61.5 billion on surging HBM demand. Tokyo’s chip complex did the rest.
But breadth was thin. The TOPIX, measured by the 1306 ETF proxy, gained just 0.67% — a gap of more than 2.6 percentage points versus the Nikkei, the signature of a rally concentrated in a handful of index-heavy names. Only 9 of 17 TOPIX-17 sectors advanced (ETF proxy basis). The yen helped at the margin, with USD/JPY quoted at 158.36 on October 1, up about 0.6% on the day.
Who Did the Lifting
| Name | Close | Day |
|---|---|---|
| Lasertec (6920) | — | +11.14% |
| Advantest (6857) | 37,610 | +9.78% |
| Murata (6981) | — | +8.43% |
| Tokyo Electron (8035) | 12,580 | +6.47% |
| SoftBank Group (9984) | 6,701 | +4.21% |
| Nidec (6594) | — | -10.83% |
| MUFG (8306) | 3,586 | -3.08% |
Within our fixed 95-name large-cap universe (not a full-market scan), the gainers were a clean sweep of semiconductor equipment and components: Lasertec on 1.5x its 20-day volume, Advantest on 1.6x, with TDK (+7.35%) and SCREEN (+7.22%) close behind. Sector-wise, Electric & Precision led at +2.98% (+2.30pp vs TOPIX), with Machinery +2.77% and Steel & Nonferrous +1.53%.
The losers were just as telling. Nidec collapsed 10.83% on 6.6x average volume — by far the day’s most violent single-stock move among tracked large caps. And financials sold off broadly: Banks fell 2.09% as a sector (-2.76pp vs TOPIX), with MUFG -3.08%, Dai-ichi Life -3.12%, and Tokio Marine -3.07%. Traditional exporters mostly sat out the party — Toyota eked out +0.17%, Sony +0.74%.
Positioning: Shorts Active, Not Panicked
The TSE short-selling ratio — our daily positioning signature — came in at 38.8% of total trading value (31.4% under the price rule plus 7.4% unrestricted), on hefty turnover of JPY 9.68 trillion. A high-30s reading points to a defensive undertone persisting even as the index ripped. Our interpretation — and the data record short-sale volume, not motive — is that a meaningful share of Thursday’s flow may have been hedging or fading the move rather than chasing it.
The Nikkei Volatility Index rose 1.09 to 22.92 — the 51st percentile of the past 915 sessions, i.e., entirely normal. No stress signal there.
JSF margin data (September 30 — the previous session; Thursday’s figures publish with a lag) showed leveraged long demand of JPY 0.68 trillion against JPY 0.20 trillion of stock lending (shares borrowed for shorting). The single-name detail is interesting: into Wednesday, SoftBank Group saw its stock-lending balance jump by 75,100 shares while margin-loan balances fell by 449,100 — shorts building and leveraged longs trimming just before Thursday’s 4.2% pop. Tokyo Electron showed a similar pattern (stock lending +33,300 shares). If those short-side builds extended into today, Thursday’s surge inflicted real pain — and 406 of 926 loanable issues (44%) were already incurring gyaku-hibu premium charges, the extra daily cost short sellers pay when borrow is tight.
On the regulatory side, JPX published 1,022 large disclosed short-position reports across 656 issues, led by ERTH Group (19.2% of shares outstanding in aggregate), KLab (18.5%), and TOWA (17.0%). These are lagged position filings — positioning context, not today’s selling. JSF restriction measures remain extensive: 85 issues under caution alerts and 343 under new-application suspensions.
Rates and the BOJ
JGBs rallied into month-end: per MOF data for September 30 (the latest available session), the 10-year yield eased 2.5bp to 3.057%, the 2-year to 1.952%, and the 30-year to 4.098%. The combination of softer yields and a yen past 158 goes some way to explaining why banks and insurers — the rate trade — were Thursday’s worst performers even on a +3.3% index day.
Weekly Flows
JPX investor-type data for the week of September 7–11 (published with a lag — these are not today’s flows) showed foreign investors as net buyers of TSE Prime equities to the tune of JPY +0.73 trillion, against modest net selling of JPY 0.05 trillion by individuals.
A caveat from the more recent MOF cross-border series (week of September 20–26, different reporting basis, direction more reliable than magnitude): foreign investors net sold JPY 0.36 trillion of Japanese equities that week, while Japanese residents net bought JPY 0.23 trillion of foreign equities. Foreign demand may have cooled since the early-September buying week — worth tracking as the lagged JPX data catches up.
What to Watch
- Breadth. A 2.6pp Nikkei–TOPIX gap and decliners outnumbering advancers on Prime is not a durable formula. Either the rally broadens beyond Electric & Precision, or the index becomes hostage to a handful of chip names.
- Short-side fuel. Thursday’s JSF balances (due with a lag) — did the SoftBank and Tokyo Electron stock-lending builds extend into the surge? With 44% of loanable issues already paying gyaku-hibu, squeeze mechanics could add a tailwind — or mark exhaustion.
- BOJ policy pricing. With the yen past 158 and bank shares underperforming sharply, the rate-policy debate stays live. Watch yen levels and any official commentary.
Disclaimer: This is an information and analysis publication, not investment advice. See our Methodology for data sources, standards, and our corrections policy.