How to Read Japan's Large-Shareholding Reports: The 5% Rule and the May 2026 Reform

When a news story says “a fund has acquired 5% of this company,” the source is usually a large-shareholding report. Under this system, an investor who accumulates a sizable stake in a listed company must disclose that fact and its purpose. It is one of the few primary sources that let outsiders track the movements of institutional investors and activists, and anyone can view it for free on EDINET.

This system was revised in a reform that took effect on May 1, 2026 ². The 5% threshold itself is unchanged, but the premises for reading a report were updated: whose stakes get aggregated, what counts as a reportable holding, and whether a simplified filing is available. This article first reviews the framework of the system, then organizes what the reform changed.

The Basics: The 5% Rule

The large-shareholding report system, in principle, requires anyone whose holding ratio of share certificates in a listed company exceeds 5% to file a large-shareholding report (Article 27-23 of the Financial Instruments and Exchange Act) ². According to the Financial Services Agency (FSA), the report (Form No. 1) must be filed within five business days of the day the holding ratio exceeds 5% ¹. This threshold is what is popularly called the “5% rule.”

Once a report has been filed, further disclosure is required whenever the holding moves. A change report must be filed “when the holding ratio increases or decreases by 1% or more from the ratio stated in the most recently filed large-shareholding report” ¹. This covers not only additional purchases but also sales that reduce the holding ratio. Tracing these change reports over time reveals whether an investor is building up a position or preparing to exit.

Besides the holding ratio, a report has a “purpose of holding” field. The investor states whether the position is a pure investment or carries an intent to influence management. It is an important clue for the reader, and it also bears on whether the special-report route (below) is available.

General Reports and Special Reports: Who Files, and When

There are two types of filing: the general report, which is the default, and the simplified special report available to institutional investors and the like. To use the special report, a notification must be submitted in advance to the Director-General of a Local Finance Bureau; once approved, the filer need not report each time an obligation arises, but may instead file within five business days of a reference date ². The FSA describes those reference dates as “the second and fourth Mondays of each month” or “the 15th and the last day of each month” ¹. It is a mechanism to ease the burden on asset managers who trade frequently and would otherwise have to disclose after every transaction.

However, not everyone may use this simplified filing. The special report is limited to cases where the purpose of holding is “pure investment or other (not aimed at important-proposal acts)” ³. In other words, when the purpose of holding is to carry out important-proposal acts, the special report is not available ². Investors who intend to press into management matters are required to use the general report each time rather than the simplified route. For readers, whether an investor discloses via a general or a special report is itself a signal of stance.

An Overview of the May 2026 Reform

The reform is grounded in the “Act Partially Amending the Financial Instruments and Exchange Act and the Act on Investment Trusts and Investment Corporations,” enacted on May 15, 2024 and promulgated on May 22 of that year ². It responded to the December 2023 report of the Financial System Council’s “Working Group on the Tender Offer System, Large-Shareholding Reporting System, etc.” ². Related amending government and cabinet ordinances were then published on July 4, 2025, finalizing the details ², and the revised system applies to cases where a reporting obligation arises on or after May 1, 2026 ².

A report by Daiwa Institute of Research summarizes the main revisions as “clarifying the scope of joint holders to promote collaborative engagement, and bringing cash-settled equity-derivative transactions within the scope of the large-shareholding report system” ². The three points below are worth keeping in mind when reading a report.

Point 1: The Scope of Joint Holders — Whose Shares Get Aggregated

Under this system, even holders below 5% individually have their stakes aggregated for the threshold test if they qualify as “joint holders.” Joint holders are divided into those under a substantive standard (substantive joint holders) and those under a formal standard (deemed joint holders) ². The reform reorganized the scope of these deemed joint holders.

One change is the exclusion of spousal relationships. Before the reform, spouses were aggregated as deemed joint holders; after the reform, spousal relationships are excluded ².

The other concerns how collaboration among institutional investors is treated. The reform introduces a framework under which parties are not treated as joint holders if all of a set of requirements are met: (a) the holder and the other holders are financial instruments business operators and the like (Type I financial instruments business operators, investment management firms, banks, trust companies, insurance companies, etc.); (b) their agreement’s purpose is not to jointly carry out important-proposal acts; and (c) the agreement to jointly exercise voting and other rights as shareholders is one made for each individual exercise of rights ². This organizes matters so that “collaborative engagement” — several institutional investors aligning their votes on a specific agenda item — does not immediately trigger aggregation and a reporting obligation, with the aim of promoting dialogue ².

At the same time, certain relationships are newly added to the deemed-joint-holder category. After the reform, external facts such as (a) interlocking-officer relationships, (b) funding relationships, and (c) the relationship between a party who requested that important-proposal acts be carried out and the party who carried them out at that request, bring the parties within the scope of deemed joint holders ². Even where an explicit agreement is hard to prove, such relationships are captured for aggregation. Excluding spouses while pulling in relationships tied together by management or funding is the overall shape of the reform.

Point 2: Bringing In Cash-Settled Derivatives

Another pillar addresses transactions that build up only an economic stake without directly holding the shares. The reform brings cash-settled derivative transactions that meet certain requirements within the scope of the large-shareholding report obligation ².

Specifically, holders of long positions in cash-settled derivatives held for certain purposes are added to those subject to the reporting obligation, so a filing obligation can arise even without holding the underlying shares ³. Previously, such cash-settled derivatives were not the shares themselves and so tended to fall outside the large-shareholding net. The reform closes this gap, with the aim of including the build-up of economic exposure within the scope of disclosure. For readers, the point to note is that a “holding” appearing in a report is no longer limited to physical shares.

Point 3: Clarifying “Important-Proposal Acts”

“Important-proposal acts” is a concept that governs whether the special report is available, and it is also a gauge of how far an investor is stepping into management. The reform organized its scope and the requirements for it to apply.

The Daiwa report summarizes that meeting all three requirements is necessary for something to constitute an important-proposal act: (1) it is a “proposal” act directed at the issuer (or its subsidiary); (2) the content of the proposal falls within items enumerated by ordinance; and (3) the purpose of the proposal act is to make a material change to, or a material impact on, the issuer’s business activities ².

On requirement (1), so long as an investor merely asks for an explanation of the issuer’s management policy, or explains its own voting policy or its holding/disposal policy, this does not amount to a “proposal” act and is not considered an important-proposal act ². The line drawn is that an investor’s dialogue with management does not, by itself, immediately constitute an important-proposal act.

The ordinance-enumerated items (requirement (2)) were themselves revised. The pre-reform items “appointment or dismissal of managers and other important employees” and “establishment, change, or abolition of branches and other important organizations” were deleted, while “appointment of a specified person as an officer” and “an acquisition that, following the acquisition of share certificates by a person other than the issuer together with its joint holders, results in holding more than 50% of the voting rights” were newly added ². Proposals bearing on officer personnel and on control were, in effect, repositioned at the center of important-proposal acts.

Reading a Report: Practical Pointers

Taken together, the way to read a large-shareholding report also shifts somewhat from May 2026. First, when looking at a holding ratio, be conscious of “who is being aggregated.” The treatment of collaborative engagement and the addition of interlocking-officer and funding relationships changed how the roster of joint holders is understood. Second, keep in mind that the holdings shown in a report are no longer limited to physical shares. Third, cross-checking the purpose-of-holding field against whether the filing is a general or a special report lets you read, with greater confidence, whether an investor is closer to a pure investor or holds an intent to engage with management.

Individual large-shareholding reports can be traced by searching EDINET. Once the framework of the system and the key points of the 2026 reform are in hand, lining up the history down to the change reports over time brings into view shifts in an investor’s intent that a single news story tends to obscure.

Sources

Overview of the Large-Shareholding Reporting System - Financial Services Agency (the 5% rule, filing deadline, change reports, special-report reference dates)
Reiwa 6 FIEA Amendment: Details of the Revisions to the Large-Shareholding Reporting System - Daiwa Institute of Research, Financial Research Dept., Kanae Yada (Oct 7, 2025; timeline of the reform, joint holders, and important-proposal acts)
What Is a Large-Shareholding Report? Overview of the System and the May 2026 Reform - M&A Capital Partners (cash-settled derivatives and the special report)