Methodology

This page defines every figure on the site and explains how the data is collected, extracted and verified. Item names on deal pages link directly to the definitions below.

Data source

All data comes from filings submitted to EDINET, the Financial Services Agency's electronic disclosure system (via EDINET API v2). No market price data or other non-filing data is used.

Coverage is tender offers for shares by persons other than the issuer (third-party tender offers). Issuer self-tender offers are excluded. The filings used are: Tender Offer Registration Statements and amendments; Notices of Withdrawal; Tender Offer Reports and amendments; Position Statements, amendments and Responses to Questions.

Original quoted text is shown in Japanese and is not translated, because its role is to show exactly what the filing says. Company names use the English names registered in EDINET where available; other names are translated or romanized by us.

How deals are defined

Deal ID: 4-digit securities code of the target - filing date of the Tender Offer Registration Statement (YYYYMMDD). The EDINET code is used if there is no securities code. IDs never change once assigned.

Linking filings: each Tender Offer Registration Statement starts one deal. Other filings are linked (1) through the parent filing recorded in EDINET, then (2) by target company, filer and proximity of filing dates. Where more than one deal is a candidate (e.g. competing offers), the filing is linked to the nearest deal and the deal is marked "Under review".

Filing date: the date the Tender Offer Registration Statement was submitted to EDINET. This is usually the first day of the offer period and usually the business day after announcement.

Type: TOB (tender offer) by default. A deal is classed as an MBO only where a filing states that the transaction constitutes a management buyout. A reference to the Tokyo Stock Exchange's "rules on MBOs, etc." alone is not treated as an MBO, because those rules also apply to acquisitions by controlling shareholders.

Status: "Closed" once a Tender Offer Report is filed, "Withdrawn" once a Notice of Withdrawal is filed, otherwise "Open".

Definitions

Offer price per common share: The tender offer price per common share (JPY) stated under "Tender offer price" in the filing. Prices for stock acquisition rights etc. are excluded. Revisions made by amended statements are shown as history, with the latest value displayed.
Premium: The premium of the offer price over the share price (%) as stated in the filing, with its basis (closing price on the business day before announcement, or 1/3/6-month simple average closing price) and reference date. These are the figures stated in the filings; we do not recalculate them from market prices. Figures are rounded to one decimal place (the original figure is in the quoted text).
Offer period: The tender offer period stated in the filing. If extended, the extended period is shown with its history.
Minimum / maximum shares: The minimum and maximum number of shares to be purchased, as stated in the acquirer's filings. Not shown if no limit is set.
Shares tendered / result: The total number of shares tendered and whether the offer succeeded, as stated in the Tender Offer Report.
MBO: Shown where a filing states the transaction is an MBO.

Valuations

Results of share valuation reports obtained by the acquirer, the target or the target's special committee from third-party valuers, as described in the filings, organized by valuer and method. These are not our own valuations.

Engaged by: Acquirer (obtained by the tender offeror), Target (obtained by the target's board), or Special committee (obtained independently by the target's special committee).
Market price method: Values the shares from closing prices or averages over set periods. Where several calculations use different reference dates, they are shown separately with the filing's own label.
Comparable companies method: Values the shares from market multiples of listed companies in similar businesses.
DCF method: Values the shares by discounting projected free cash flows to present value.
Value per share: The range of the valuation result (low to high, JPY).
Discount rate: The discount rate used in the DCF method (usually the weighted average cost of capital), as a range (%).
Perpetual growth rate: The perpetual growth rate used for the terminal value in the DCF method, as a range (%). Not shown where the terminal value uses only an exit multiple.

Extraction

Filings are converted to text (the HTML body in the XBRL package, or the PDF). For amended filings we use the PDF, which contains only the changes.
Only paragraphs containing relevant keywords and figures (plus neighbouring paragraphs) are selected, with keywords chosen by filing type.
A large language model (LLM) extracts values in a fixed JSON schema, together with a verbatim quote from the filing for every value.

Verification

Every extracted value is checked automatically, and only values that pass all checks are published:

The quote actually appears in the filing (ignoring differences in character width, line breaks and thousands separators).
The extracted figure or date actually appears in the quote.
Ranges have low ≤ high; discount rates are within 1–30%, perpetual growth rates within −5–10%, and premiums within −50–300%.

Values that fail are re-extracted with a more capable model; any that still fail are withheld for manual review (deal pages show only the count). Offer terms are taken only from the acquirer's filings; the target's Position Statement is used for premiums, MBO status and valuations.

Where filings for the same deal disagree, changes made by amendments are shown as history and other differences are flagged as inconsistent (under review).

Statistics

The premium distribution uses the premium over the closing price on the business day before announcement, as stated in the filing.
For discount rates and perpetual growth rates, each DCF valuation contributes one point per deal and valuer: the midpoint of the stated range.
Valuer names are unified using abbreviations defined in the filing and by ignoring the legal-entity suffix. A valuer counts once per deal even if it used several methods.
When the same valuation appears in both the tender offer registration statement and the position statement, it is counted once (valuations with the same valuer, engaging side and values are treated as the same, regardless of how the method is written).
The special committee's valuer and the target's valuer are compared only within the same deal, where both produced a DCF valuation. Comparing different sets of deals would mix in differences in industry and size.
For where the price landed, each DCF value-per-share range is shown relative to the offer price, for deals with a DCF valuation on both the acquirer side and the target side.
Industry effects (large for discount and growth rates) are not yet adjusted for. Industry breakdowns will be added as coverage grows.

Limitations

Values are extracted automatically and may contain errors. Always check the original filing.
Deals whose Tender Offer Registration Statement predates the collection period are not included.
Transactions without public disclosure are not covered.

Change log

September 2026: first release (tender offers over the past year; offer terms, premiums and valuations).