Who has been buying Core Concept Technologies Inc. stock?

13 distinct investors have filed 30 disclosed large-shareholding filings in Core Concept Technologies Inc. (4371), most recently on 2026-05-07. 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 Core Concept Technologies Inc. have?

Core Concept Technologies Inc. has 30 buy-side and 47 sell-side disclosures on record, covering ¥19.1B ($123.5M) in total reported value, spanning 2021-09-29 to 2026-05-07.

Where does StockDrifts get Core Concept 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.

Core Concept Technologies Inc. 4371

Company

株式会社コアコンセプト・テクノロジーCore Concept Technologies Inc.

Investors

Buys

Total Value

¥19.1B ($123.5M)

Avg Return

-9.67%

Last Filing

2026-05-07

Core Concept Technologies Inc. (4371) has 30 disclosed large-shareholding filings and 47 disclosed disposals on record, filed by 13 distinct investors. Together those filings cover ¥19.1B ($123.5M) in reported transaction value. The earliest filing StockDrifts holds for Core Concept Technologies Inc. is dated 2021-09-29; the most recent is 2026-05-07. 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 -9.67%, 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
2026-07-17	BUY	Market Buy	株式会社シグマクシス・ホールディングス SIGMAXYZ Holdings Inc.	activist	2.6M	¥1,372	+11.2%	¥249M ($1.6M)
2026-06-19	BUY	Market Buy	株式会社シグマクシス・ホールディングス SIGMAXYZ Holdings Inc.	activist	2.4M	¥1,406	-2.4%	¥248M ($1.6M)
2026-06-05	BUY	Market Buy	株式会社シグマクシス・ホールディングス SIGMAXYZ Holdings Inc.	activist	2.2M	¥1,397	+5.5%	¥253M ($1.6M)
2026-05-22	BUY	Market Buy	株式会社シグマクシス・ホールディングス SIGMAXYZ Holdings Inc.	activist	2.1M	¥1,253	+12.2%	¥241M ($1.6M)
2026-05-07	BUY	Market Buy	株式会社シグマクシス・ホールディングス SIGMAXYZ Holdings Inc.	strategic	1.9M	¥1,299	+7.5%	¥245M ($1.6M)
2026-04-27	BUY	Market Buy	株式会社シグマクシス・ホールディングス SIGMAXYZ Holdings Inc.	strategic	1.7M	¥1,401	-12.3%	¥656M ($4.2M)
2026-04-22	BUY	Market Buy	株式会社シグマクシス・ホールディングス SIGMAXYZ Holdings Inc.	strategic	1.2M	¥1,404	-12.5%	¥467M ($3.0M)
2026-04-13	BUY	unknown	株式会社シグマクシス・ホールディングス SIGMAXYZ Holdings Inc.	strategic	883.6K	¥900	+47.6%	¥795M ($5.1M)
2024-12-20	SELL	unknown	アセットマネジメントOneインターナショナル Asset Management One International Ltd.	unknown	0	¥895	-56.4%	¥23M ($151K)
2024-12-20	SELL	unknown	アセットマネジメントOne株式会社 Asset Management One Co., Ltd.	other	820.3K	¥895	-56.4%	¥219M ($1.4M)
2024-06-05	SELL	unknown	金子武史 Kaneko Takeshi	activist	2.3M	¥2,075	+32.5%	¥14M ($93K)
2024-04-30	SELL	unknown	芸陽線材株式会社 Geiyo Wire Co., Ltd.	strategic	1.6M	¥2,300	+39.1%	¥314M ($2.0M)
2024-04-30	SELL	unknown	芸陽線材株式会社 Geiyo Wire Co., Ltd.	strategic	1.6M	¥2,300	+39.1%	¥314M ($2.0M)
2024-04-30	SELL	unknown	髙盛豊文 Takamori Toyofumi	strategic	720.0K	¥2,300	+39.1%	¥238M ($1.5M)
2024-04-30	SELL	unknown	グッドエコ株式会社 Good Eco Co., Ltd.	strategic	800.0K	¥2,300	+39.1%	¥159M ($1.0M)
2024-04-30	SELL	unknown	グッドエコ株式会社 Good Eco Co., Ltd.	strategic	800.0K	¥2,300	+39.1%	¥159M ($1.0M)
2024-04-30	SELL	unknown	髙盛豊文 Takamori Toyofumi	strategic	720.0K	¥2,300	+39.1%	¥238M ($1.5M)
2023-11-30	SELL	unknown	芸陽線材株式会社 Geiyo Wire Co., Ltd.	strategic	800.0K	¥2,888	+51.5%	¥70M ($451K)
2023-11-30	SELL	unknown	髙盛豊文 Takamori Toyofumi	strategic	340.0K	¥2,888	+51.5%	¥149M ($960K)
2023-11-30	SELL	unknown	グッドエコ株式会社 Good Eco Co., Ltd.	strategic	400.0K	¥2,888	+51.5%	¥36M ($233K)
2023-11-30	SELL	unknown	芸陽線材株式会社 Geiyo Wire Co., Ltd.	strategic	800.0K	¥2,888	+51.5%	¥70M ($451K)
2023-11-30	SELL	unknown	グッドエコ株式会社 Good Eco Co., Ltd.	strategic	400.0K	¥2,888	+51.5%	¥36M ($233K)
2023-11-30	SELL	unknown	髙盛豊文 Takamori Toyofumi	strategic	340.0K	¥2,888	+51.5%	¥149M ($960K)
2023-10-20	BUY	Market Buy	アセットマネジメントOne株式会社 Asset Management One Co., Ltd.	other	1.1M	¥2,550	-45.1%	¥474M ($3.1M)
2023-10-20	BUY	Market Buy	アセットマネジメントOneインターナショナル Asset Management One International Ltd.	other	25.2K	¥2,550	-45.1%	¥22M ($143K)
2023-09-12	SELL	unknown	田口雅美 Masami Taguchi	strategic	40.0K	¥2,774	+49.5%	¥111M ($715K)
2023-09-12	SELL	unknown	津野尾肇 Tsunoo Hajime	activist	590.0K	¥2,774	+49.5%	¥978M ($6.3M)
2023-09-12	SELL	unknown	グッドエコ株式会社 Good Eco Co., Ltd.	strategic	750.0K	¥2,774	+49.5%	¥260M ($1.7M)
2023-09-12	SELL	unknown	芸陽線材株式会社 Geiyo Wire Co., Ltd.	strategic	1.0M	¥2,774	+49.5%	¥1.9B ($12.3M)
2023-09-12	SELL	unknown	グッドエコ株式会社 Good Eco Co., Ltd.	strategic	750.0K	¥2,774	+49.5%	¥386M ($2.5M)
2023-09-12	SELL	unknown	芸陽線材株式会社 Geiyo Wire Co., Ltd.	strategic	1.0M	¥2,774	+49.5%	¥2.2B ($14.0M)
2023-09-12	SELL	unknown	グッドエコ株式会社 Good Eco Co., Ltd.	strategic	750.0K	¥2,774	+49.5%	¥463M ($3.0M)
2023-09-12	SELL	unknown	芸陽線材株式会社 Geiyo Wire Co., Ltd.	strategic	1.0M	¥2,774	+49.5%	¥2.3B ($14.9M)
2023-09-12	SELL	unknown	株式会社BIPED BIPED Co., Ltd.	strategic	1.4M	¥2,774	+49.5%	¥217M ($1.4M)
2023-09-12	SELL	unknown	金子武史 Kaneko Takeshi	activist	2.3M	¥2,774	+49.5%	¥1.2B ($8.0M)
2023-09-12	SELL	unknown	下村克則 Shimomura Katsunori	strategic	860.0K	¥2,774	+49.5%	¥1.6B ($10.3M)
2023-09-12	BUY	unknown	田口紀成 Taguchi Tadaaki	activist	685.0K	¥2,774	-49.5%	¥1.9B ($12.1M)
2023-09-12	SELL	unknown	髙盛豊文 Takamori Toyofumi	strategic	670.0K	¥2,774	+49.5%	¥549M ($3.5M)
2023-09-12	SELL	unknown	髙盛豊文 Takamori Toyofumi	strategic	670.0K	¥2,774	+49.5%	¥231M ($1.5M)
2023-09-12	SELL	unknown	髙盛豊文 Takamori Toyofumi	strategic	670.0K	¥2,774	+49.5%	¥246M ($1.6M)
2023-07-27	BUY	unknown	田口雅美 Masami Taguchi	strategic	80.0K	¥2,912	-51.9%	¥233M ($1.5M)
2023-07-27	BUY	unknown	田口紀成 Taguchi Tadaaki	activist	1.1M	¥2,912	-51.9%	¥3.1B ($19.7M)
2023-07-03	BUY	unknown	津野尾肇 Tsunoo Hajime	activist	940.0K	¥3,285	-57.4%	¥808M ($5.2M)
2023-07-03	BUY	unknown	津野尾肇 Tsunoo Hajime	activist	940.0K	¥3,285	-57.4%	¥808M ($5.2M)
2023-06-12	BUY	unknown	田口雅美 Masami Taguchi	strategic	80.0K	¥2,650	-47.2%	¥212M ($1.4M)
2023-06-12	BUY	unknown	田口雅美 Masami Taguchi	strategic	80.0K	¥2,650	-47.2%	¥212M ($1.4M)
2023-06-12	BUY	unknown	田口紀成 Taguchi Tadaaki	activist	1.2M	¥2,650	-47.2%	¥3.1B ($19.9M)
2023-06-12	BUY	unknown	田口紀成 Taguchi Tadaaki	activist	1.2M	¥2,650	-47.2%	¥3.1B ($19.9M)
2023-04-28	BUY	unknown	田口雅美 Masami Taguchi	strategic	80.0K	¥3,420	-59.1%	¥274M ($1.8M)
2023-04-28	BUY	unknown	田口雅美 Masami Taguchi	strategic	80.0K	¥3,420	-59.1%	¥274M ($1.8M)

Showing the 50 most recent of 95 filings.

Frequently asked questions

Who has been buying Core Concept Technologies Inc. stock?: 13 distinct investors have filed 30 disclosed large-shareholding filings in Core Concept Technologies Inc. (4371), most recently on 2026-05-07. 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 Core Concept Technologies Inc. have?: Core Concept Technologies Inc. has 30 buy-side and 47 sell-side disclosures on record, covering ¥19.1B ($123.5M) in total reported value, spanning 2021-09-29 to 2026-05-07.
Where does StockDrifts get Core Concept 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 Core Concept Technologies Inc.. For how StockDrifts scores these disclosures, see the Japan insider signal tier research, or browse every Japanese stock we track.