Who has been buying Seikagaku Corporation stock?

12 distinct investors have filed 14 disclosed large-shareholding filings in Seikagaku Corporation (4548), most recently on 2025-10-23. 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 Seikagaku Corporation have?

Seikagaku Corporation has 14 buy-side and 11 sell-side disclosures on record, covering ¥8.2B ($52.6M) in total reported value, spanning 2021-09-24 to 2025-10-23.

Where does StockDrifts get Seikagaku 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.

Seikagaku Corporation 4548

Company

生化学工業株式会社Seikagaku Corporation

Investors

Buys

Total Value

¥8.2B ($52.6M)

Avg Return

+2.67%

Last Filing

2025-10-23

Seikagaku Corporation (4548) has 14 disclosed large-shareholding filings and 11 disclosed disposals on record, filed by 12 distinct investors. Together those filings cover ¥8.2B ($52.6M) in reported transaction value. The earliest filing StockDrifts holds for Seikagaku Corporation is dated 2021-09-24; the most recent is 2025-10-23. 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 +2.67%, 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
2025-10-23	BUY	Market Buy	株式会社糖功 Toko Co., Ltd.	activist	500.0K	¥678	+8.4%	¥339M ($2.2M)
2025-10-23	BUY	Market Buy	水谷建 Ken Mizutani	activist	483.3K	¥678	+8.4%	¥328M ($2.1M)
2025-10-23	BUY	Market Buy	株式会社開生社 Kaiseisha Co., Ltd.	activist	9.9M	¥678	+8.4%	¥389M ($2.5M)
2025-10-23	BUY	Market Buy	新業株式会社 SHINGYO CO.,LTD.	activist	7.8M	¥678	+8.4%	¥5.3B ($34.3M)
2025-08-19	BUY	Market Buy	新業株式会社 SHINGYO CO.,LTD.	activist	7.8M	¥664	+10.7%	¥5.2B ($33.6M)
2025-08-19	BUY	Market Buy	株式会社糖功 Toko Co., Ltd.	activist	500.0K	¥664	+10.7%	¥332M ($2.1M)
2025-08-19	BUY	Market Buy	水谷建 Ken Mizutani	activist	483.3K	¥664	+10.7%	¥4M ($24K)
2025-08-19	BUY	Market Buy	株式会社開生社 Kaiseisha Co., Ltd.	activist	9.3M	¥664	+10.7%	¥8M ($49K)
2025-08-18	SELL	negotiated	三菱UFJモルガン・スタンレー証券株式会社 Mitsubishi UFJ Morgan Stanley Securities Co., Ltd.	other	30.8K	¥651	-12.9%	¥70M ($453K)
2025-08-18	BUY	negotiated	三菱UFJアセットマネジメント株式会社 Mitsubishi UFJ Financial Group Inc.	passive	354.7K	¥651	+12.9%	¥18M ($119K)
2025-08-18	SELL	negotiated	三菱UFJ信託銀行株式会社 Mitsubishi UFJ Financial Group Inc.	passive	1.0M	¥651	-12.9%	¥74M ($477K)
2025-08-18	SELL	negotiated	株式会社三菱UFJ銀行 Mitsubishi UFJ Financial Group Inc.	strategic	536.7K	¥651	-12.9%	¥651M ($4.2M)
2025-08-14	BUY	Market Buy	株式会社糖功 Toko Co., Ltd.	activist	500.0K	¥643	+14.3%	¥322M ($2.1M)
2025-08-14	BUY	Market Buy	水谷建 Ken Mizutani	activist	483.3K	¥643	+14.3%	¥4M ($24K)
2025-08-14	BUY	Market Buy	株式会社開生社 Kaiseisha Co., Ltd.	activist	9.3M	¥643	+14.3%	¥1.3B ($8.3M)
2025-08-14	BUY	Market Buy	新業株式会社 SHINGYO CO.,LTD.	activist	7.8M	¥643	+14.3%	¥5.0B ($32.5M)
2025-08-14	BUY	negotiated	新業株式会社 SHINGYO CO.,LTD.	activist	7.8M	¥643	+14.3%	¥5.0B ($32.5M)
2025-08-14	BUY	negotiated	株式会社糖功 Toko Co., Ltd.	activist	500.0K	¥643	+14.3%	¥322M ($2.1M)
2025-08-14	BUY	negotiated	水谷建 Ken Mizutani	activist	483.3K	¥643	+14.3%	¥4M ($24K)
2025-08-14	BUY	negotiated	株式会社開生社 Kaiseisha Co., Ltd.	activist	9.3M	¥643	+14.3%	¥1.3B ($8.3M)
2025-08-06	SELL	unknown	インベスコ・アセット・マネジメント株式会社 Invesco Asset Management (Japan) Limited	other	2.7M	¥656	-12.0%	¥380M ($2.5M)
2025-03-21	SELL	unknown	インベスコホンコンリミテッド Invesco Hong Kong Limited	other	0	¥790	+7.0%	¥81M ($521K)
2025-03-21	SELL	unknown	インベスコ・アセット・マネジメント株式会社 Invesco Asset Management (Japan) Limited	other	3.3M	¥790	+7.0%	¥426M ($2.8M)
2024-11-05	BUY	Market Buy	水谷建 Ken Mizutani	activist	476.1K	¥860	-14.5%	¥5M ($32K)
2024-11-05	BUY	Market Buy	株式会社糖功 Toko Co., Ltd.	activist	500.0K	¥860	-14.5%	¥430M ($2.8M)
2024-11-05	BUY	Market Buy	株式会社開生社 Kaiseisha Co., Ltd.	activist	7.3M	¥860	-14.5%	¥6.3B ($40.5M)
2024-11-05	BUY	Market Buy	新業株式会社 SHINGYO CO.,LTD.	activist	7.8M	¥860	-14.5%	¥6.7B ($43.5M)
2024-09-20	SELL	unknown	インベスコホンコンリミテッド Invesco Hong Kong Limited	other	99.9K	¥836	+12.1%	¥19M ($123K)
2024-09-20	BUY	unknown	インベスコ・アセット・マネジメント株式会社 Invesco Asset Management (Japan) Limited	other	3.8M	¥836	-12.1%	¥3.2B ($20.5M)
2024-09-03	BUY	negotiated	株式会社糖功 Toko Co., Ltd.	activist	500.0K	¥847	-13.2%	¥424M ($2.7M)
2024-09-03	BUY	negotiated	水谷建 Ken Mizutani	activist	476.1K	¥847	-13.2%	¥5M ($31K)
2024-09-03	BUY	negotiated	株式会社開生社 Kaiseisha Co., Ltd.	activist	7.3M	¥847	-13.2%	¥6.2B ($39.9M)
2024-09-03	BUY	negotiated	新業株式会社 SHINGYO CO.,LTD.	activist	7.8M	¥847	-13.2%	¥6.6B ($42.9M)
2024-07-29	BUY	negotiated	三菱UFJモルガン・スタンレー証券株式会社 Mitsubishi UFJ Morgan Stanley Securities Co., Ltd.	other	138.6K	¥881	-16.6%	¥122M ($788K)
2024-07-29	BUY	negotiated	三菱UFJアセットマネジメント株式会社 Mitsubishi UFJ Financial Group Inc.	passive	321.1K	¥881	-16.6%	¥55M ($355K)
2024-07-29	SELL	negotiated	三菱UFJ信託銀行株式会社 Mitsubishi UFJ Financial Group Inc.	passive	1.1M	¥881	+16.6%	¥130M ($840K)
2024-07-29	BUY	negotiated	株式会社三菱UFJ銀行 Mitsubishi UFJ Financial Group Inc.	strategic	1.5M	¥881	-16.6%	¥1.4B ($8.7M)
2024-05-21	SELL	unknown	インベスコホンコンリミテッド Invesco Hong Kong Limited	other	124.7K	¥776	+5.3%	¥22M ($142K)
2024-05-21	BUY	unknown	インベスコ・アセット・マネジメント株式会社 Invesco Asset Management (Japan) Limited	other	4.2M	¥776	-5.3%	¥3.2B ($20.6M)
2023-12-15	BUY	negotiated	株式会社糖功 Toko Co., Ltd.	activist	500.0K	¥741	-0.8%	¥371M ($2.4M)
2023-12-15	BUY	negotiated	水谷建 Ken Mizutani	activist	471.2K	¥741	-0.8%	¥25M ($163K)
2023-12-15	BUY	negotiated	株式会社開生社 Kaiseisha Co., Ltd.	activist	7.3M	¥741	-0.8%	¥5.4B ($34.9M)
2023-12-15	BUY	negotiated	新業株式会社 SHINGYO CO.,LTD.	activist	7.8M	¥741	-0.8%	¥5.8B ($37.5M)
2021-09-24	SELL	unknown	アセットマネジメントOne株式会社 Asset Management One Co., Ltd.	other	957.7K	¥1,131	+35.0%	¥276M ($1.8M)
2021-09-24	SELL	unknown	株式会社みずほ銀行 Mizuho Bank, Ltd.	strategic	1.6M	¥1,131	+35.0%	¥450M ($2.9M)

Frequently asked questions

Who has been buying Seikagaku Corporation stock?: 12 distinct investors have filed 14 disclosed large-shareholding filings in Seikagaku Corporation (4548), most recently on 2025-10-23. 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 Seikagaku Corporation have?: Seikagaku Corporation has 14 buy-side and 11 sell-side disclosures on record, covering ¥8.2B ($52.6M) in total reported value, spanning 2021-09-24 to 2025-10-23.
Where does StockDrifts get Seikagaku 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 Seikagaku Corporation. For how StockDrifts scores these disclosures, see the Japan insider signal tier research, or browse every Japanese stock we track.