Who has been buying Sansei Technologies, Inc. stock?

6 distinct investors have filed 4 disclosed large-shareholding filings in Sansei Technologies, Inc. (6357), most recently on 2026-03-16. 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 Sansei Technologies, Inc. have?

Sansei Technologies, Inc. has 4 buy-side and 3 sell-side disclosures on record, covering ¥1.9B ($12.1M) in total reported value, spanning 2021-11-25 to 2026-03-16.

Where does StockDrifts get Sansei Technologies, Inc. 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.

Sansei Technologies, Inc. 6357

Company

三精テクノロジーズ株式会社Sansei Technologies, Inc.

Investors

Buys

Total Value

¥1.9B ($12.1M)

Avg Return

+87.87%

Last Filing

2026-03-16

Sansei Technologies, Inc. (6357) has 4 disclosed large-shareholding filings and 3 disclosed disposals on record, filed by 6 distinct investors. Together those filings cover ¥1.9B ($12.1M) in reported transaction value. The earliest filing StockDrifts holds for Sansei Technologies, Inc. is dated 2021-11-25; the most recent is 2026-03-16. 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 +87.87%, 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
2026-03-16	BUY	unknown	株式会社三井住友銀行	other	805.9K	¥2,252	+4.0%	¥1.7B ($11.2M)
2026-03-16	BUY	unknown	三井住友カード株式会社	other	692.4K	¥2,252	+4.0%	¥1.5B ($9.7M)
2026-03-16	SELL	unknown	三井住友DSアセットマネジメント株式会社	passive	315.5K	¥2,252	+4.0%	¥682M ($4.4M)
2026-03-16	SELL	unknown	SMBC日興証券株式会社	other	67.7K	¥2,252	+4.0%	¥146M ($943K)
2026-03-02	BUY	acquisition	丸一鋼管株式会社 Maruichi Steel Tube Ltd.	other	1.7M	¥2,548	-15.2%	¥1.2B ($7.7M)
2026-03-02	BUY	unknown	三井住友カード株式会社	other	692.4K	¥2,548	+15.2%	¥1.5B ($9.7M)
2026-03-02	BUY	unknown	三井住友DSアセットマネジメント株式会社	passive	319.9K	¥2,548	-15.2%	¥691M ($4.5M)
2026-03-02	BUY	unknown	株式会社三井住友銀行	other	805.9K	¥2,548	+15.2%	¥1.7B ($11.2M)
2026-03-02	BUY	unknown	SMBC日興証券株式会社	other	260.9K	¥2,548	+15.2%	¥564M ($3.6M)
2025-08-08	BUY	Market Buy	三井住友カード株式会社 Sumitomo Mitsui Card Co., Ltd.	other	692.4K	¥1,980	+9.1%	¥1.4B ($8.8M)
2025-08-08	BUY	Market Buy	株式会社三井住友銀行 Sumitomo Mitsui Banking Corporation	other	805.9K	¥1,980	+9.1%	¥1.6B ($10.3M)
2025-08-08	BUY	Market Buy	三井住友DSアセットマネジメント株式会社 Sumitomo Mitsui DS Asset Management Company, Limited	passive	195.0K	¥1,980	+9.1%	¥386M ($2.5M)
2022-03-22	BUY	Market Buy	丸一鋼管株式会社 Maruichi Steel Tube Ltd.	other	1.2M	¥774	+179.2%	¥156M ($1.0M)
2022-01-20	BUY	acquisition	丸一鋼管株式会社 Maruichi Steel Tube Ltd.	other	1.0M	¥714	+202.7%	¥719M ($4.6M)
2022-01-20	BUY	unknown	丸一鋼管株式会社 Maruichi Steel Tube Ltd.	other	1.0M	¥714	+202.7%	¥719M ($4.6M)
2021-11-25	SELL	unknown	鳥海節夫相続人代表鳥海裕二 YUJI TORIUMI	unknown	0	¥781	-176.7%	¥1.3B ($8.3M)

Frequently asked questions

Who has been buying Sansei Technologies, Inc. stock?: 6 distinct investors have filed 4 disclosed large-shareholding filings in Sansei Technologies, Inc. (6357), most recently on 2026-03-16. 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 Sansei Technologies, Inc. have?: Sansei Technologies, Inc. has 4 buy-side and 3 sell-side disclosures on record, covering ¥1.9B ($12.1M) in total reported value, spanning 2021-11-25 to 2026-03-16.
Where does StockDrifts get Sansei Technologies, Inc. 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 Sansei Technologies, Inc.. For how StockDrifts scores these disclosures, see the Japan insider signal tier research, or browse every Japanese stock we track.