EDINET explained: how Japan's large shareholding and insider filings work

What EDINET is, and what it is not

EDINET stands for Electronic Disclosure for Investors' NETwork. It is the mandatory electronic disclosure system operated by Japan's Financial Services Agency (FSA), and every listed company and major fund in Japan files its regulated disclosure documents through it. Think of it as Japan's answer to the SEC's EDGAR: annual securities reports (yukashoken hokokusho), quarterly reports, extraordinary reports, tender offer documents, and the filings this guide is about, the Large Shareholding Reports.

The important thing to get straight up front is what EDINET does not contain. Japan does not run a per-executive, per-trade disclosure like the US Form 4 through EDINET. There is no public stream where a company director's every purchase and sale of their own stock lands within days. The insider-relevant filings you can actually pull from EDINET are ownership filings: the Large Shareholding Reports that fire when someone crosses 5% of a company. If you come to Japan expecting a Form 4 feed and go looking for it on EDINET, you will not find one. The separate officer trading reports exist, but they live in a different channel, described near the end of this guide.

The governing law: FIEA

All of this sits under one statute, the Financial Instruments and Exchange Act (FIEA), in Japanese the Kinsho-ho, Act No. 25 of 1948 as heavily amended. The FIEA is the master securities law of Japan. It defines the disclosure obligations, the insider-trading prohibitions, and the reporting duties for large holders and for company insiders. When a Japanese filing cites an article number in the 27-2x range, that is the Large Shareholding chapter of the FIEA.

The 5% Rule: Large Shareholding Reports

The core of public ownership transparency in Japan is what practitioners simply call the 5% Rule.

When a holder's holding ratio of a listed company's share certificates exceeds 5%, that holder must submit a Large Shareholding Report (tairyo hoyu hokokusho). The filing goes to the relevant Local Finance Bureau through EDINET, where it becomes public. The 5% test is a beneficial-ownership test: it aggregates the shares held by the filer together with those of joint holders and closely related parties, so a group acting together crosses the line collectively even if no single member holds 5% alone.

The five business day deadline

The report is due within five business days from the day the holding first exceeds 5%. That is the headline number for the initial filing. It is a business-day clock, not calendar days, and it runs from the day the threshold is crossed.

Change Reports on 1% moves

The obligation does not end with the first filing. Once a holder is above 5% and on the record, any subsequent increase or decrease of 1% or more in the holding ratio triggers a Change Report (henko hokokusho), again within five business days. Selling down through those 1% steps is reportable too, not just buying up, so the record captures accumulation and distribution alike. This is what makes the Japanese ownership record readable as a running position rather than a single snapshot: a serious holder leaves a trail of the initial report plus a series of change reports as the stake moves.

The Special Reporting route for institutions

A large fraction of the filers in this stream are not activists or founders but banks, asset managers, and securities firms whose stakes drift above and below 5% in the ordinary course of managing money. Requiring a fresh filing within five days of every transaction would be unworkable for them, so the FIEA provides a relaxed alternative.

Qualifying institutional investors (securities companies, investment managers, banks, trust banks, insurers, and their foreign equivalents) can use the Special Reporting System under FIEA Article 27-26. Instead of reporting each move within five business days, they report their position as of a reference date set roughly every two weeks, and file within five business days of that reference date. The trade-off is a condition: the relaxed route is available only for passive, ordinary-course holdings. The moment the holding is used to effect a material change in the issuer's business or control, the institution loses the exception and falls back to the standard five-day, per-event regime. This is why a filing from Nomura or BlackRock reads differently from one filed by an activist fund: one is a periodic institutional snapshot, the other is an event-driven position that has to be reported as it moves.

How to read a Large Shareholding Report

A Large Shareholding Report follows a standard structure. These are the fields that carry the meaning:

Two fields deserve the first look. The holding ratio against the prior holding ratio tells you the direction and size of the move. The purpose of holding tells you the intent: a stake filed as pure investment is a very different signal from one filed with a stated aim of influencing management, which in Japan is often the opening move of an activist campaign.

Interpretation traps

It is a stake report, not a trade report

The single biggest mistake is to read a Large Shareholding Report as if it were a US Form 4. It is not a report of a single trade by a company insider. It is a report that a holder's total position has crossed a threshold or moved by 1%. One report can bundle many underlying transactions, and the filer is frequently an institution or a fund, not an officer of the company. The signal is about ownership concentration, not about a director's read on their own stock.

Institutional churn is mostly noise

Because banks and asset managers routinely wander across the 5% line, a large share of filings are periodic Special Reporting snapshots that reflect fund flows, index rebalancing, and client mandates rather than any view on the specific company. A Nomura or a Mitsubishi UFJ crossing 5% in a large-cap name is usually plumbing, not conviction. The filings worth attention are the ones with a purpose of holding that signals intent, or a fast series of change reports concentrating a stake.

Five business days can lag a fast-moving stake

The five-business-day window means the public record trails reality. In an accumulation, a holder can be building for the better part of a week before the first report appears, and each subsequent 1% step carries the same lag. The Japanese record is timely by international standards but it is not real time.

The 5% Rule is under reform

Japan has been tightening this regime. Amendments to the Large Shareholding reporting rules under the FIEA are set to take effect in 2026, narrowing some exemptions and adjusting how joint holders and the intent test are treated. Filing patterns around the transition will shift for regulatory reasons, so treat any comparison across the change with care and check the FSA's current guidance for the parameters in force on the date you are reading a filing.

Officers and major shareholders: a separate channel

Japan does regulate insiders' own trading, just not through the public EDINET Large Shareholding stream. Under FIEA Article 163, officers (directors and statutory auditors) and major shareholders, defined as holders of 10% or more of a listed company's voting rights, must file a report on their trading in that company's specified securities with a Local Finance Bureau, in principle by the fifteenth day of the month following the transaction. Article 164 adds a short-swing profit rule modelled on the US Section 16(b): if such an insider buys and sells (or sells and buys) within any six-month window, the company can claw back the profit, regardless of whether inside information was used. These duties are real, but the reports flow through the Local Finance Bureau channel rather than the public Large Shareholding feed, so do not assume they are searchable on EDINET the way an ownership report is.

How insiders-trades.com tracks EDINET

We ingest Japan's ownership disclosures from EDINET, parsing the Large Shareholding Reports and their change reports into structured records: filer, issuer, holding ratio, direction of the move, and the stated purpose of holding. Because the same holder threads a company through an initial report and a run of change reports, we reconstruct the position over time rather than treating each filing as an isolated event. Filer roles are normalised into the same taxonomy we apply across 28 regulators, so an institutional custodian and an activist fund land in the buckets that make them comparable to filers elsewhere in the world.

Browse the live output on the Japan market hub, or start from a company page such as SoftBank Corp, Nomura Securities, or Effissimo Capital Management. For a sense of what a prolific Japanese ownership filer looks like, the large institutional holders dominate: see Nomura Securities, Mitsubishi UFJ Financial Group, and BlackRock Japan, each of which crosses the 5% line across many names.

For how other regimes handle the same problem, compare our SEC Form 4 guide (the per-executive model Japan does not run on EDINET) and our DART Korea guide (a close cousin with both ownership and holding reports). The full picture is in the insider disclosure rules by country index.