Who has been buying Koken Boring Machine Co.,Ltd. stock?

7 distinct investors have filed 7 disclosed large-shareholding filings in Koken Boring Machine Co.,Ltd. (6297), most recently on 2025-08-08. Each filer, their role, the number of shares and the price at filing are listed in the table on this page.

How many insider filings does Koken Boring Machine Co.,Ltd. have?

Koken Boring Machine Co.,Ltd. has 7 buy-side and 7 sell-side disclosures on record, covering ¥5.7B ($36.5M) in total reported value, spanning 2021-05-10 to 2025-08-08.

Where does StockDrifts get Koken Boring Machine Co.,Ltd. insider data?

From EDINET large-shareholding (5%+) reports — the official filing system run by the Financial Services Agency (Japan). StockDrifts parses each disclosure and matches it to daily price history; the original filings remain available directly from EDINET.

Do insider buys in Japanese stocks predict returns?

Not uniformly. StockDrifts scored 101,000+ Japanese large-shareholding filings on fixed 12-month forward returns and found the predictive power concentrated in specific filer types and filing patterns rather than spread evenly across all disclosures.

Koken Boring Machine Co.,Ltd. 6297

Company

鉱研工業株式会社Koken Boring Machine Co.,Ltd.

Investors

Buys

Total Value

¥5.7B ($36.5M)

Avg Return

+17.97%

Last Filing

2025-08-08

Koken Boring Machine Co.,Ltd. (6297) has 7 disclosed large-shareholding filings and 7 disclosed disposals on record, filed by 7 distinct investors. Together those filings cover ¥5.7B ($36.5M) in reported transaction value. The earliest filing StockDrifts holds for Koken Boring Machine Co.,Ltd. is dated 2021-05-10; the most recent is 2025-08-08. All of it is parsed from EDINET large-shareholding (5%+) reports, the official disclosure system operated by the Financial Services Agency (Japan). Across these filings the average return since disclosure is +17.97%, measured from each filing date to the latest available close.

Price & insider activity (12 months)

Recent filings

Date	Type	Source	Insider	Purpose	Shares	Price at filing	Return	Value
2025-08-08	SELL	unknown	株式会社エンバイオ・ホールディングス EnBio Holdings,Inc	unknown	0	¥760	+0.1%	¥583M ($3.8M)
2025-08-07	SELL	unknown	みずほ証券株式会社 Mizuho Securities Co., Ltd.	other	7.8K	¥760	+0.1%	¥274M ($1.8M)
2025-08-07	SELL	unknown	株式会社みずほ銀行 Mizuho Bank, Ltd.	unknown	0	¥760	+0.1%	¥87M ($563K)
2025-08-06	BUY	unknown	楽天証券株式会社 Rakuten Securities Inc	other	6.9K	¥760	-0.1%	¥68M ($440K)
2025-08-05	SELL	unknown	日立建機株式会社 Hitachi Construction Machinery Co., Ltd.	unknown	0	¥760	+0.1%	¥595M ($3.8M)
2025-08-01	SELL	unknown	鉱研工業取引先持株会理事長中山尚 Takashi Nakayama	strategic	0	¥759	+0.0%	¥415M ($2.7M)
2025-07-30	BUY	acquisition	ヒューリック株式会社 Hulic Co.,Ltd.	activist	7.2M	¥759	+0.0%	¥5.5B ($35.2M)
2025-07-23	BUY	unknown	楽天証券株式会社 Rakuten Securities Inc	other	600.1K	¥763	-0.5%	¥458M ($3.0M)
2025-07-18	BUY	negotiated	株式会社エンバイオ・ホールディングス EnBio Holdings,Inc	strategic	767.0K	¥763	-0.5%	¥585M ($3.8M)
2025-07-18	BUY	negotiated	株式会社エンバイオ・ホールディングス EnBio Holdings,Inc	strategic	767.0K	¥763	-0.5%	¥585M ($3.8M)
2025-07-07	BUY	unknown	みずほ証券株式会社 Mizuho Securities Co., Ltd.	other	368.6K	¥761	-0.3%	¥281M ($1.8M)
2025-07-07	BUY	unknown	株式会社みずほ銀行 Mizuho Bank, Ltd.	strategic	115.0K	¥761	-0.3%	¥88M ($565K)
2024-01-15	BUY	Market Buy	鉱研工業取引先持株会理事長中山尚 Takashi Nakayama	strategic	546.7K	¥483	+57.1%	¥44M ($285K)
2024-01-15	BUY	unknown	鉱研工業取引先持株会理事長中山尚 Takashi Nakayama	strategic	546.7K	¥483	+57.1%	¥44M ($285K)
2023-08-28	SELL	unknown	日立建機株式会社 Hitachi Construction Machinery Co.,Ltd.	strategic	783.0K	¥494	-53.6%	¥99M ($638K)
2022-07-15	BUY	unknown	鉱研工業取引先持株会理事長中山尚 Takashi Nakayama	strategic	455.1K	¥447	+69.8%	¥203M ($1.3M)
2021-05-10	SELL	unknown	日立建機株式会社 Hitachi Construction Machinery Co., Ltd.	strategic	983.0K	¥538	-41.1%	¥296M ($1.9M)

Frequently asked questions

Who has been buying Koken Boring Machine Co.,Ltd. stock?: 7 distinct investors have filed 7 disclosed large-shareholding filings in Koken Boring Machine Co.,Ltd. (6297), most recently on 2025-08-08. Each filer, their role, the number of shares and the price at filing are listed in the table on this page.
How many insider filings does Koken Boring Machine Co.,Ltd. have?: Koken Boring Machine Co.,Ltd. has 7 buy-side and 7 sell-side disclosures on record, covering ¥5.7B ($36.5M) in total reported value, spanning 2021-05-10 to 2025-08-08.
Where does StockDrifts get Koken Boring Machine Co.,Ltd. insider data?: From EDINET large-shareholding (5%+) reports — the official filing system run by the Financial Services Agency (Japan). StockDrifts parses each disclosure and matches it to daily price history; the original filings remain available directly from EDINET.
Do insider buys in Japanese stocks predict returns?: Not uniformly. StockDrifts scored 101,000+ Japanese large-shareholding filings on fixed 12-month forward returns and found the predictive power concentrated in specific filer types and filing patterns rather than spread evenly across all disclosures.

Source filings

Every trade listed above is disclosed in EDINET large-shareholding (5%+) reports, filed with the Financial Services Agency (Japan). View the original EDINET filings for Koken Boring Machine Co.,Ltd.. For how StockDrifts scores these disclosures, see the Japan insider signal tier research, or browse every Japanese stock we track.