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Status: "Closed" once a Tender Offer Report is filed, "Withdrawn" once a Notice of Withdrawal is filed, otherwise "Open".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 (%). Where rates are given business by business (segment or sum-of-the-parts valuations), they are listed under the method for each business. Those rates are not comparable with company-wide rates and would count one deal several times, so they are left out of the statistics (distributions, medians, valuer comparisons).
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.

Deal characteristics

Deal characteristics are read from the target's position statement (or, if there is none, the tender offer registration statement). As with figures, each comes with a verbatim quote, and only those whose quote is found in the filing are published.

Category (take-private, partial offer, discount TOB)

Take-private: delisting is planned after the offer (MBOs, squeeze-outs by a parent, acquisitions by funds or strategic buyers).
Partial offer: a stake is acquired or increased while the listing is kept (usually with a maximum number of shares).
Discount TOB: the offer price is deliberately set below the market price to buy shares from a specific shareholder, on the assumption that other shareholders will not tender. The listing is usually kept.

A take-private whose offer price ended up below the market price because the share price rose before announcement (for example on press reports or expectations of a competing bid) is classed as a take-private, not a discount TOB. Where the filing does not make the category clear, a deal with a maximum number of shares and a negative premium over the prior-day close is inferred to be a discount TOB, one with a maximum as a partial offer, and any other as a take-private; the deal page says so.

Two-step tender offers (a first offer at a premium for general shareholders, then a second at a lower price for specific major shareholders) are treated as separate deals: the first as a take-private and the second as a discount TOB. A deal is not classed as a discount TOB if its offer price carries a premium over the prior-day close, even if the filing mentions a discount.

Treatment in statistics: premium studies generally cover take-privates (acquisitions of control) only. Partial offers often do not transfer control, and discount TOBs assume a negative premium, so the motive for paying a premium differs. Following this practice, premium distributions, offer price positions and negotiation statistics use take-privates only; partial offers and discount TOBs are shown separately.

Acquirer type

Management (MBO, including fund-backed deals described as MBOs), parent or existing major shareholder (a company already holding a stake), financial sponsor (not an MBO), strategic buyer (no or a small existing stake), or other.

Auction

The target or the selling shareholder chose the acquirer from several candidates through a bidding or selection process.

Valuer engaged by the special committee

A third-party valuer engaged by the special committee itself, separate from the valuer engaged by the target's board.

Fairness opinion

An opinion that the offer price is fair from a financial point of view. We show who obtained it (target, special committee or acquirer) and the provider. "Not stated" covers both "not obtained" and no mention.

Offer price negotiation and increase

The acquirer's proposed prices (first, revised and final) and the prices requested by the target or special committee, as described in the position statement. The increase runs from the acquirer's first proposal to the final offer price (including increases made by amended statements). Proposals whose date cannot be confirmed in the quote are shown without a date. Deals where prices straddle a stock split, two-step tender offers, and deals whose final price is below the first proposal (likely mixing in other bidders' proposals in an auction) show the proposal history only and are excluded from the increase calculation and statistics.

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 take-privates only. Partial offers and discount TOBs are shown separately.
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.
Sector breakdowns group the TSE 33 industries into TOPIX-17 sectors (no values are shown for sectors with fewer than 5 deals). Other statistics, such as valuer tendencies, are not adjusted for sector.
Comparisons with and without a committee valuer, a fairness opinion or an auction simply set the groups side by side and do not show causation.

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).
September 2026: coverage extended to five years. Added deal characteristics (category, acquirer type, auctions, special committees, fairness opinions, offer price negotiation) and statistics by category and sector.