Who has been buying Round One Corporation stock?

11 distinct investors have filed 15 disclosed large-shareholding filings in Round One Corporation (4680), most recently on 2026-05-11. 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 Round One Corporation have?

Round One Corporation has 15 buy-side and 10 sell-side disclosures on record, covering ¥23.9B ($154.0M) in total reported value, spanning 2021-04-07 to 2026-05-11.

Where does StockDrifts get Round One 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.

Round One Corporation 4680

Company

株式会社ラウンドワンRound One Corporation

Investors

Buys

Total Value

¥23.9B ($154.0M)

Avg Return

+89.72%

Last Filing

2026-05-11

Round One Corporation (4680) has 15 disclosed large-shareholding filings and 10 disclosed disposals on record, filed by 11 distinct investors. Together those filings cover ¥23.9B ($154.0M) in reported transaction value. The earliest filing StockDrifts holds for Round One Corporation is dated 2021-04-07; the most recent is 2026-05-11. 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 +89.72%, 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
2026-05-11	BUY	Market Buy	アモーヴァ・アセットマネジメント株式会社	other	4.6M	¥872.1	+7.6%	¥202M ($1.3M)
2026-05-11	SELL	unknown	三井住友トラスト・アセットマネジメント株式会社	other	7.4M	¥872.1	-7.6%	¥2.5B ($16.4M)
2026-01-21	BUY	unknown	アモーヴァ・アセットマネジメント株式会社	other	4.3M	¥1,102.5	-15.1%	¥4.1B ($26.2M)
2026-01-21	BUY	unknown	三井住友トラスト・アセットマネジメント株式会社	other	10.3M	¥1,102.5	-15.1%	¥9.6B ($62.2M)
2023-10-13	SELL	unknown	杉野公亮 Kosuke Sugino	strategic	35.0M	¥544	-72.1%	¥63M ($403K)
2023-10-13	BUY	unknown	杉野公亮 Kosuke Sugino	strategic	35.0M	¥544	+72.1%	¥63M ($403K)
2022-12-07	BUY	unknown	アセットマネジメントOne株式会社 Asset Management One Co., Ltd.	other	11.5M	¥578	+62.0%	¥6.6B ($42.3M)
2022-12-07	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	895.8K	¥578	-62.0%	¥233M ($1.5M)
2022-11-08	SELL	unknown	フィデリティ投信株式会社 FIL Investments (Japan) Limited	other	12.2M	¥638	-46.7%	¥3.0B ($19.5M)
2022-09-26	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	428.8K	¥678	-38.1%	¥207M ($1.3M)
2022-09-26	BUY	unknown	アセットマネジメントOne株式会社 Asset Management One Co., Ltd.	other	4.8M	¥678	+38.1%	¥3.2B ($20.6M)
2022-07-07	SELL	unknown	フィデリティ投信株式会社 FIL Investments (Japan) Limited	other	5.6M	¥470	-99.2%	¥601M ($3.9M)
2022-04-22	BUY	Market Buy	フィデリティ投信株式会社 FIL Investments (Japan) Limited	other	6.9M	¥492	+90.3%	¥531M ($3.4M)
2022-01-21	BUY	Market Buy	フィデリティ投信株式会社 FIL Investments (Japan) Limited	other	5.8M	¥461.33	+102.9%	¥454M ($2.9M)
2021-12-22	BUY	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	732.0K	¥457.67	+104.5%	¥335M ($2.2M)
2021-12-22	BUY	unknown	アセットマネジメントOne株式会社 Asset Management One Co., Ltd.	other	5.4M	¥457.67	+104.5%	¥2.5B ($16.1M)
2021-10-05	BUY	unknown	杉野公亮 Kousuke Sugino	strategic	11.7M	¥523.33	+78.9%	¥6.1B ($39.4M)
2021-08-20	BUY	unknown	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	1.4M	¥357.33	+162.0%	¥201M ($1.3M)
2021-08-20	SELL	unknown	株式会社三井住友銀行 Sumitomo Mitsui Banking Corporation	other	328.0K	¥357.33	-162.0%	¥327M ($2.1M)
2021-08-20	BUY	unknown	SMBC日興証券株式会社 SMBC Nikko Securities Inc.	other	214.3K	¥357.33	+162.0%	¥65M ($417K)
2021-08-06	BUY	unknown	株式会社三井住友銀行 Sumitomo Mitsui Banking Corporation	other	1.2M	¥361	+159.3%	¥448M ($2.9M)
2021-08-06	BUY	unknown	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	869.9K	¥361	+159.3%	¥314M ($2.0M)
2021-08-06	BUY	unknown	SMBC日興証券株式会社 SMBC Nikko Securities Inc.	other	2.9M	¥361	+159.3%	¥1.1B ($6.8M)
2021-07-20	SELL	negotiated	杉野公彦 Masahiko Sugino	activist	19.9M	¥372	-151.6%	¥99M ($641K)
2021-07-07	SELL	Market Buy	ラッセル・インベストメント・インプリメンテーション・サービシーズ・エル・エル・シー(RUSSELL INVESTMENTS IMPLEMENTATION SERVICES, LLC) RUSSELL INVESTMENTS IMPLEMENTATION SERVICES, LLC	passive	3.5M	¥480.33	-94.9%	¥656M ($4.2M)
2021-06-07	BUY	unknown	フィデリティ投信株式会社 FIL Investments (Japan) Limited	other	4.8M	¥523.67	+78.8%	¥2.5B ($16.3M)
2021-04-07	SELL	Market Buy	ラッセル・インベストメント・インプリメンテーション・サービシーズ・エル・エル・シー(RUSSELL INVESTMENTS IMPLEMENTATION SERVICES, LLC) RUSSELL INVESTMENTS IMPLEMENTATION SERVICES, LLC	passive	4.8M	¥394.67	-137.2%	¥399M ($2.6M)

Frequently asked questions

Who has been buying Round One Corporation stock?: 11 distinct investors have filed 15 disclosed large-shareholding filings in Round One Corporation (4680), most recently on 2026-05-11. 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 Round One Corporation have?: Round One Corporation has 15 buy-side and 10 sell-side disclosures on record, covering ¥23.9B ($154.0M) in total reported value, spanning 2021-04-07 to 2026-05-11.
Where does StockDrifts get Round One 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 Round One Corporation. For how StockDrifts scores these disclosures, see the Japan insider signal tier research, or browse every Japanese stock we track.