Who has been buying Seiko Corporation stock?

8 distinct investors have filed 1 disclosed large-shareholding filings in Seiko Corporation (6286), most recently on 2026-05-12. 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 Seiko Corporation have?

Seiko Corporation has 1 buy-side and 7 sell-side disclosures on record, covering ¥425M ($2.7M) in total reported value, spanning 2023-11-29 to 2026-05-12.

Where does StockDrifts get Seiko Corporation 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.

Seiko Corporation 6286

Company

靜甲株式会社Seiko Corporation

Investors

Buys

Total Value

¥425M ($2.7M)

Avg Return

+72.26%

Last Filing

2026-05-12

Seiko Corporation (6286) has 1 disclosed large-shareholding filings and 7 disclosed disposals on record, filed by 8 distinct investors. Together those filings cover ¥425M ($2.7M) in reported transaction value. The earliest filing StockDrifts holds for Seiko Corporation is dated 2023-11-29; the most recent is 2026-05-12. 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 +72.26%, 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
2026-05-12	BUY	unknown	鈴木與平	other	71.0K	¥1,552	-6.6%	¥110M ($711K)
2026-05-12	BUY	unknown	柏興業株式会社	other	38.0K	¥1,552	-6.6%	¥59M ($380K)
2026-05-12	BUY	unknown	清水食品株式会社	other	204.0K	¥1,552	-6.6%	¥317M ($2.0M)
2026-05-12	BUY	negotiated	鈴与ホールディングス株式会社	strategic	1.8M	¥1,552	-6.6%	¥2.8B ($18.3M)
2026-05-12	BUY	unknown	鈴木與平	other	71.0K	¥1,552	-6.6%	¥110M ($711K)
2026-05-12	BUY	unknown	柏興業株式会社	other	38.0K	¥1,552	-6.6%	¥59M ($380K)
2026-05-12	BUY	unknown	清水食品株式会社	other	204.0K	¥1,552	-6.6%	¥317M ($2.0M)
2026-05-12	BUY	negotiated	鈴与ホールディングス株式会社	strategic	1.8M	¥1,552	-6.6%	¥2.8B ($18.3M)
2026-03-12	BUY	unknown	鈴木武夫	activist	30.0K	¥1,651	+6.7%	¥46M ($298K)
2026-03-12	BUY	unknown	有限会社テイエムケイ	activist	540.6K	¥1,651	+6.7%	¥833M ($5.4M)
2026-03-12	BUY	unknown	鈴木惠子	activist	427.4K	¥1,651	+6.7%	¥658M ($4.2M)
2026-03-10	BUY	unknown	鈴木武夫	activist	30.0K	¥1,638	+6.0%	¥46M ($298K)
2026-03-10	SELL	unknown	有限会社テイエムケイ	activist	540.6K	¥1,638	+6.0%	¥833M ($5.4M)
2026-03-10	BUY	unknown	鈴木惠子	activist	427.4K	¥1,638	+6.0%	¥658M ($4.2M)
2026-03-10	BUY	unknown	鈴木武夫	activist	30.0K	¥1,638	+6.0%	¥46M ($298K)
2026-03-10	SELL	unknown	有限会社テイエムケイ	activist	540.6K	¥1,638	+6.0%	¥833M ($5.4M)
2026-03-10	BUY	unknown	鈴木惠子	activist	427.4K	¥1,638	+6.0%	¥658M ($4.2M)
2026-03-10	BUY	unknown	鈴木武夫	activist	30.0K	¥1,638	+6.0%	¥46M ($298K)
2026-03-10	SELL	unknown	有限会社テイエムケイ	activist	540.6K	¥1,638	+6.0%	¥833M ($5.4M)
2026-03-10	BUY	unknown	鈴木惠子	activist	427.4K	¥1,638	+6.0%	¥658M ($4.2M)
2025-05-14	BUY	unknown	鈴木孝典 Takanori Suzuki	activist	475.9K	¥894	+72.3%	¥425M ($2.7M)
2025-05-09	BUY	unknown	鈴木武夫 Takeo Suzuki	activist	30.0K	¥908	+69.6%	¥27M ($176K)
2025-05-09	SELL	unknown	鈴木惠子 Keiko Suzuki	activist	427.4K	¥908	-69.6%	¥363M ($2.3M)
2025-05-09	BUY	unknown	有限会社テイエムケイ TMK Co., Ltd.	activist	617.6K	¥908	+69.6%	¥561M ($3.6M)
2024-10-18	BUY	unknown	鈴木武夫 Takeo Suzuki	activist	30.0K	¥700	+120.0%	¥21M ($135K)
2024-10-18	BUY	unknown	有限会社テイエムケイ TMK Co., Ltd.	activist	617.6K	¥700	+120.0%	¥432M ($2.8M)
2024-10-18	SELL	unknown	鈴木惠子 Keiko Suzuki	activist	827.4K	¥700	-120.0%	¥51M ($331K)
2023-11-29	BUY	unknown	有限会社テイエムケイ TMK Co., Ltd.	unknown	617.6K	¥662	+132.6%	¥409M ($2.6M)
2023-11-29	BUY	unknown	鈴木武夫 Takeo Suzuki	activist	30.0K	¥662	+132.6%	¥20M ($128K)
2023-11-29	BUY	unknown	有限会社テイエムケイ TMK Co., Ltd.	activist	617.6K	¥662	+132.6%	¥409M ($2.6M)
2023-11-29	BUY	unknown	鈴木武夫 Takeo Suzuki	unknown	30.0K	¥662	+132.6%	¥20M ($128K)
2023-11-29	SELL	unknown	鈴木惠子 Keiko Suzuki	activist	900.4K	¥662	-132.6%	¥57M ($366K)
2023-11-29	SELL	unknown	鈴木惠子 Keiko Suzuki	activist	900.4K	¥662	-132.6%	¥57M ($366K)

Frequently asked questions

Who has been buying Seiko Corporation stock?: 8 distinct investors have filed 1 disclosed large-shareholding filings in Seiko Corporation (6286), most recently on 2026-05-12. 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 Seiko Corporation have?: Seiko Corporation has 1 buy-side and 7 sell-side disclosures on record, covering ¥425M ($2.7M) in total reported value, spanning 2023-11-29 to 2026-05-12.
Where does StockDrifts get Seiko Corporation 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 Seiko Corporation. For how StockDrifts scores these disclosures, see the Japan insider signal tier research, or browse every Japanese stock we track.