The JPX-Nikkei Index 400 is not simply Japan’s 400 largest companies. Its annual selection process first filters the eligible Tokyo-listed universe, then ranks 1,000 stocks using profitability and scale, and finally applies limited governance and disclosure adjustments. For an international investor, that makes membership a useful research clue—but not a buy signal or a complete quality score.
The current process is set out by Japan Exchange Group and Nikkei Indexes. The latest periodic review was announced on August 7, 2026, and the disclosed 2026 constituent set took effect on August 31.
How the JPX-Nikkei 400 selection process works
The index normally holds 400 common stocks whose main market is the Tokyo Stock Exchange Prime, Standard or Growth market. The process has four practical stages: an eligibility screen, a liquidity screen that identifies 1,000 candidates, a weighted quantitative ranking, and a complementary qualitative adjustment.
The important distinction is that the selection process and the index calculation are not the same thing. A company can qualify through the annual ranking, while its influence on the index later depends on free-float-adjusted market value and a constituent cap.
Stage 1: who reaches the 1,000-stock screen
The first screen excludes companies that have been listed for under three years, except technical listings. It also excludes companies with excess liabilities in any of the past three fiscal years, companies with operating deficits in all three of those years, companies with overall deficits in all three, and securities designated for delisting or a comparable status.
From the remaining names, the method selects the top 1,000 in consideration of trading value over the most recent three years and market capitalization on the selection base date. That base date is the last business day of June for the annual review. JPX’s current guidebook is the best reference for the detailed terms and exceptions.
This stage answers a narrow question: does the company enter the ranking pool? It does not tell a reader that the stock is inexpensive, that its daily liquidity will meet a particular order size, or that it is a durable business.
Stage 2 and 3: weighted scoring plus limited qualitative adjustment
Each of the 1,000 screened companies receives a rank score for three quantitative indicators. The first-ranked company on an indicator receives 1,000 points and the 1,000th receives one point; the method then applies the weights below. JPX notes that it has handling rules for negative return on equity and operating profit.
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| Selection input | Weight in quantitative score | What it captures | What it does not establish |
|---|---|---|---|
| Three-year average return on equity | 40% | Multi-year profitability relative to shareholders’ equity | A forecast of future profitability or a valuation judgment |
| Three-year cumulative operating profit | 40% | Aggregate operating earnings over the stated three-year period | Free cash flow, dividend capacity or balance-sheet strength by itself |
| Market capitalization on the selection base date | 20% | Company scale at the June selection date | A company’s later market value or investability for every investor |
After that quantitative score, the index provider can add a complementary qualitative score for a majority of independent directors, female board members or executive officers, adoption or scheduled adoption of International Financial Reporting Standards, and English earnings information or a corporate-governance report disclosed through TDnet, the Tokyo Stock Exchange’s disclosure service. The official overview says this adjustment is calibrated so that at most around ten constituents differ from a selection based on the quantitative score alone.
That last point matters. The JPX-Nikkei 400 incorporates governance and disclosure signals, but it is not a full governance rating. Readers who want to examine a board or reporting practice should still work through the issuer’s filings; this independent-directors guide is a useful starting point.
Stage 4: how the final 400 and the annual review are set
Existing constituents receive a continuity buffer: they remain selected if their final score ranks within the top 440. The remaining slots are generally filled from high-ranking names that meet the stated return-on-equity condition and rank within the top 400 on the final score. A further rule based on three-year average return on equity fills any remaining places.
The annual review uses the last business day of June as its selection base date. Results are announced on the fifth business day of August, and the constituent review occurs on the last business day of August. The 2026 periodic-review notice confirms the August 31 application date for this year’s disclosed constituent list.
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| Calendar item | Normal timing | Practical reader use |
|---|---|---|
| Selection base date | Last business day of June | Separate the measurement date from later market moves |
| Review results announced | Fifth business day of August | Read the official notice and constituent data rather than headlines alone |
| Review applied | Last business day of August | Confirm the effective list and any later non-periodic removals |
| Next ordinary review | August of the following year | Revisit the guidebook for methodology changes before assuming the same rules |
Between ordinary reviews, a deletion—such as one caused by delisting—does not normally trigger a replacement just to bring the count back to 400. The current guidebook also says that the number of constituents can temporarily fall below 400 between reviews.
Selection is different from index weighting
Once constituents are set, the index is free-float-adjusted market-value weighted, not equally weighted. The current methodology caps a constituent’s ratio at 1.5% at the annual-review selection base date. Free float means the proportion of listed shares judged available for market trading; it is not a corporate governance grade and it is not the same as the total shares outstanding.
This is why an investor should avoid reading the index as a simple league table. A high-scoring smaller constituent need not have the same index weight as a much larger one, and a large company’s presence does not mean it leads on every profitability or governance input. For price-versus-return context, see ATG Press’s Nikkei 225 total-return index guide.
How to use the JPX-Nikkei 400 in company research
- Confirm whether the company is in the current official constituent file; do not rely on an old fund factsheet or a search snippet.
- Treat membership as a prompt to examine the company’s multi-year return on equity, operating profit, market value, board independence and English disclosure practice.
- Check the company’s TSE segment separately. Prime, Standard and Growth are market labels, not JPX-Nikkei 400 membership tests; ATG Press’s TSE market-segment guide explains the difference.
- Read the underlying disclosures. TDnet English is a practical route to issuer announcements, while the cost-of-capital disclosure tracker guide adds a capital-efficiency lens.
- Compare the index label with the risks the methodology does not score directly: cyclicality, debt, customer concentration, valuation, currency exposure and current trading conditions.
Key takeaways
- The JPX-Nikkei 400 chooses 400 Tokyo-listed common stocks through a multi-stage annual method; it is not a list of Japan’s largest companies.
- Three-year average return on equity and three-year cumulative operating profit carry 40% each of the quantitative score, while market capitalization carries 20%.
- Governance and English-disclosure factors can influence the final selection, but only as a limited complement to the quantitative result.
- The annual selection base date is the last business day of June; the review is applied on the last business day of August.
- Membership is useful evidence for research, not a recommendation, valuation conclusion or forecast.
Sources
- Japan Exchange Group: JPX-Nikkei Index 400 — official overview and selection rules, accessed 2026-10-05.
- JPX Market Innovation and Research and Nikkei: JPX-Nikkei Index 400 Guidebook — current guidebook, published 2026-08-03; accessed 2026-10-05.
- Nikkei Indexes: JPX-Nikkei Index 400 profile — current profile and review overview, accessed 2026-10-05.
- Japan Exchange Group: 2026 periodic review notice — published 2026-08-07; accessed 2026-10-05.
This article is for informational purposes only and does not constitute investment advice.
