About & Disclaimer
Who are "big investors"?
Investment entities that manage capital large enough to move market prices in stocks and other financial markets.
- Institutional investors (domestic & foreign): Pension funds (e.g. GPIF), mutual funds, life insurers, sovereign wealth funds
- Hedge funds: Funds pursuing absolute returns over short-to-medium terms (heavy use of short-selling and derivatives)
- Activist investors: Funds demanding higher dividends, buybacks, or management improvements from companies
- Wealthy individuals / "whales": Individual investors who nonetheless move hundreds of millions of yen
This site classifies filers into 14 categories. See the glossary below.
Why track big-investor moves
- Reading the flow of capital (trends): Sustained stock-price rises and falls are driven by big investors accumulating or selling. This matters as a trend-following signal.
- Screening for stock selection: Whether a company's fundamentals and growth meet the research bar of large professional investors serves as a useful filter.
What "big-investor moves" means
"Big-investor moves" refers to when and how much of a listed company's shares were bought or sold by an entity with market-moving capital — institutional investors, activist funds, founder-family holding companies, or the issuer itself through buybacks. In Japan, investors who acquire 5% or more of a company's shares must file a large-shareholding report with EDINET (the Financial Services Agency's disclosure system) — the so-called "5% rule" — and must re-file a change report if their holding ratio moves by 1 percentage point or more. This site tracks that public information daily.
About this site
Big Investor Watch is the English edition of 大口投資家の監視ブログ (kujira-watch.com), a blog that monitors and explains the moves of "whales" (financial-industry slang for large investors with enough capital to move the market) based on public information such as EDINET large-shareholding reports. The Japanese edition carries every disclosure along with per-stock and per-investor holding histories; the English edition covers a subset of articles.
Data sources & update method
- Deal information is fetched daily from EDINET large-shareholding reports. Both directions are covered — increases (acquisitions) and decreases (transfers/sales) in holding ratio — with sell-direction articles tagged "Sell".
- Deal size is an estimate calculated from shares outstanding × share price × change in holding ratio. EDINET disclosures themselves do not state a yen amount, so this is not a guaranteed exact figure.
- Articles are generated by AI from the filing's factual data, and reviewed or corrected by a human as needed. The English edition is a translation of the Japanese article; only a subset of articles has an English edition.
- Where a source (timely disclosure, press release, etc.) is identifiable, a link is included in the article.
About the source (EDINET)
The disclosure information this site covers comes from EDINET, the official electronic disclosure system operated by Japan's Financial Services Agency (FSA). You can search the original filings yourself using the links below.
- EDINET (document search)
- EDINET API specification (the official FSA API this site uses for automated retrieval)
Investor classification (glossary)
The label on each article classifies the filer of the large-shareholding report into one of the categories below.
- Prime Broker
- Held via a securities firm's prime brokerage business (often client short-sale collateral, not necessarily an investment decision).
- Activist Investor
- A fund seeking management influence or proposing shareholder resolutions.
- Venture Capital
- Venture capital — often a pre-IPO stake retained after listing.
- PE / Mezzanine Fund
- Private equity, buyout, or mezzanine funds.
- Independent Boutique Asset Manager
- A domestic independent asset manager not affiliated with a megabank or insurer group.
- Domestic Asset Manager
- A traditional asset manager affiliated with a megabank or insurer group (including trust-bank trust accounts).
- Foreign Traditional Asset Manager
- A large, diversified asset manager headquartered overseas.
- Japanese Securities Firm / Bank
- A Japanese securities firm or bank itself (not its asset-management subsidiary).
- Individual
- Holdings under an individual's name, such as an executive or major shareholder.
- Founder-Family Holding Company
- A privately held asset-management company owned by a company's founding family.
- Public-Interest / General Foundation
- Non-profit public-interest or general incorporated foundations.
- Operating Company
- A general (non-financial) operating company, domestic or foreign.
- Other
- A filer that does not clearly fit the categories above, or could not be determined.
- Share Buyback
- The issuer's own share repurchase (TDnet timely disclosure), showing the board-approved upper limit.
Contact
The operator does not publish a name or email address. Questions and corrections can be sent to @kujira_watch on X.
Disclaimer
The content of this site is for informational purposes only and does not recommend or solicit any specific security or investment decision. We do not guarantee the accuracy or completeness of the information provided, and the operator assumes no responsibility for any damages resulting from its use. Please make all investment decisions at your own risk.