Who has been buying CellSource Co., Ltd. stock?

6 distinct investors have filed 2 disclosed large-shareholding filings in CellSource Co., Ltd. (4880), most recently on 2025-12-19. 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 CellSource Co., Ltd. have?

CellSource Co., Ltd. has 2 buy-side and 23 sell-side disclosures on record, covering ¥2.7B ($17.1M) in total reported value, spanning 2021-06-07 to 2025-12-19.

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.

CellSource Co., Ltd. 4880

Company

セルソース株式会社CellSource Co., Ltd.

Investors

Buys

Total Value

¥2.7B ($17.1M)

Avg Return

-92.45%

Last Filing

2025-12-19

CellSource Co., Ltd. (4880) has 2 disclosed large-shareholding filings and 23 disclosed disposals on record, filed by 6 distinct investors. Together those filings cover ¥2.7B ($17.1M) in reported transaction value. The earliest filing StockDrifts holds for CellSource Co., Ltd. is dated 2021-06-07; the most recent is 2025-12-19. Across these filings the average return since disclosure is -92.45%, 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
2026-09-16	BUY	Market Buy	シリアルインキュベート株式会社	strategic	6.9M	¥332	-2.1%	¥1.7B ($10.7M)
2026-09-16	SELL	unknown	山川雅之	strategic	2.2M	¥332	+2.1%	¥1.7B ($10.7M)
2025-12-19	SELL	unknown	シリアルインキュベート株式会社	strategic	1.9M	¥395	+17.7%	¥783K ($5K)
2025-12-19	SELL	unknown	山川雅之	strategic	7.2M	¥395	+17.7%	¥2M ($15K)
2025-05-07	BUY	unknown	裙本理人 Masato Tsumamoto	strategic	1.4M	¥647	-	-
2025-02-14	SELL	unknown	裙本理人 Masato Tsumamoto	strategic	1.4M	¥841	+61.4%	¥2M ($11K)
2024-03-11	SELL	unknown	裙本理人 Masato Tsumamoto	strategic	1.4M	¥1,405	+76.9%	¥3M ($18K)
2024-03-11	SELL	unknown	山川雅之 Masayuki Yamakawa	strategic	7.2M	¥1,405	+76.9%	¥25M ($162K)
2024-03-11	SELL	unknown	シリアルインキュベート株式会社 Serial Incubate Co., Ltd.	strategic	1.9M	¥1,405	+76.9%	¥6M ($36K)
2023-11-13	BUY	unknown	裙本理人 Masato Tsumamoto	strategic	1.4M	¥1,599	-	-
2023-11-06	SELL	unknown	山川雅之 Masayuki Yamakawa	strategic	7.2M	¥1,816	+82.1%	¥789M ($5.1M)
2023-11-06	BUY	unknown	シリアルインキュベート株式会社 Serial Incubate Co., Ltd.	strategic	1.9M	¥1,816	-	-
2023-10-16	SELL	unknown	山川雅之 Masayuki Yamakawa	strategic	7.6M	¥1,964	+83.5%	¥2.6B ($16.7M)
2023-10-16	SELL	unknown	裙本理人 Masato Tsumamoto	strategic	1.4M	¥1,964	+83.5%	¥2.9B ($18.8M)
2023-10-16	SELL	unknown	シリアルインキュベート株式会社 Serial Incubate Co., Ltd.	strategic	1.9M	¥1,964	+83.5%	¥136M ($876K)
2023-10-03	BUY	unknown	裙本理人 Masato Tsumamoto	strategic	2.7M	¥2,392	-	-
2023-10-03	SELL	unknown	山川雅之 Masayuki Yamakawa	strategic	8.6M	¥2,392	+86.4%	¥410M ($2.6M)
2023-10-03	SELL	unknown	シリアルインキュベート株式会社 Serial Incubate Co., Ltd.	strategic	1.9M	¥2,392	+86.4%	¥91M ($588K)
2023-09-11	BUY	unknown	裙本理人 Masato Tsumamoto	strategic	2.7M	¥2,468	-	-
2023-09-11	BUY	unknown	裙本理人 Masato Tsumamoto	strategic	2.7M	¥2,468	-	-
2023-06-20	SELL	unknown	裙本理人 Masato Tsumamoto	strategic	2.7M	¥3,005	+89.2%	¥29M ($185K)
2022-12-23	SELL	unknown	山川雅之 Masayuki Yamakawa	strategic	8.6M	¥3,850	+91.6%	¥43M ($278K)
2022-12-23	SELL	unknown	シリアルインキュベート株式会社 Serial Incubate Co., Ltd.	strategic	1.9M	¥3,850	+91.6%	¥14M ($93K)
2022-12-22	SELL	unknown	シリアルインキュベート株式会社 Serial Incubate Co., Ltd.	strategic	633.6K	¥4,185	+92.2%	¥10M ($67K)
2022-12-22	SELL	unknown	山川雅之 Masayuki Yamakawa	strategic	2.9M	¥4,185	+92.2%	¥46M ($300K)
2022-03-03	SELL	unknown	山川雅之 Masayuki Yamakawa	strategic	8.6M	¥3,705	+91.2%	¥373M ($2.4M)
2022-03-03	SELL	unknown	山川雅之 Masayuki Yamakawa	strategic	8.6M	¥3,705	+91.2%	¥498M ($3.2M)
2022-03-03	SELL	unknown	シリアルインキュベート株式会社 Serial Incubate Co., Ltd.	strategic	1.9M	¥3,705	+91.2%	¥55M ($357K)
2022-01-05	SELL	unknown	裙本理人 Masato Tsumamoto	strategic	2.7M	¥4,810	+93.2%	¥99M ($636K)
2021-09-24	BUY	unknown	みずほ証券株式会社 Mizuho Securities Co., Ltd.	other	8.4K	¥6,609.99	-	-
2021-09-24	BUY	unknown	アセットマネジメントOne株式会社 Asset Management One Co., Ltd.	other	206.9K	¥6,609.99	-95.1%	¥1.3B ($8.7M)
2021-06-07	SELL	unknown	みずほ証券株式会社 Mizuho Securities Co., Ltd.	other	8.4K	¥4,240	+92.3%	¥60M ($389K)
2021-06-07	BUY	unknown	アセットマネジメントOne株式会社 Asset Management One Co., Ltd.	other	312.5K	¥4,240	-92.3%	¥1.3B ($8.5M)
2021-06-07	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.	other	4.4K	¥4,240	+92.3%	¥39M ($254K)

Frequently asked questions

Who has been buying CellSource Co., Ltd. stock?: 6 distinct investors have filed 2 disclosed large-shareholding filings in CellSource Co., Ltd. (4880), most recently on 2025-12-19. 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 CellSource Co., Ltd. have?: CellSource Co., Ltd. has 2 buy-side and 23 sell-side disclosures on record, covering ¥2.7B ($17.1M) in total reported value, spanning 2021-06-07 to 2025-12-19.
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.

More on this data

Every trade listed above comes from an official regulatory disclosure. For how StockDrifts scores these disclosures, see the Japan insider signal tier research, or browse every Japanese stock we track.