Who has been buying OpenWork Inc. stock?

8 distinct investors have filed 26 disclosed large-shareholding filings in OpenWork Inc. (5139), most recently on 2026-02-09. 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 OpenWork Inc. have?

OpenWork Inc. has 26 buy-side and 17 sell-side disclosures on record, covering ¥6.4B ($41.3M) in total reported value, spanning 2022-12-21 to 2026-02-09.

Where does StockDrifts get OpenWork 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.

OpenWork Inc. 5139

Company

オープンワーク株式会社OpenWork Inc.

Investors

Buys

Total Value

¥6.4B ($41.3M)

Avg Return

+1.25%

Last Filing

2026-02-09

OpenWork Inc. (5139) has 26 disclosed large-shareholding filings and 17 disclosed disposals on record, filed by 8 distinct investors. Together those filings cover ¥6.4B ($41.3M) in reported transaction value. The earliest filing StockDrifts holds for OpenWork Inc. is dated 2022-12-21; the most recent is 2026-02-09. 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 +1.25%, 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
2026-02-09	SELL	unknown	増井慎二郎 Shinjiro Masui	other	3.6M	¥1,147	+18.9%	¥252M ($1.6M)
2025-08-19	SELL	unknown	増井慎二郎 Shinjiro Masui	other	3.8M	¥1,289	+27.9%	¥292M ($1.9M)
2025-03-06	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	1.1M	¥875	+6.3%	¥934M ($6.0M)
2024-11-21	SELL	unknown	増井慎二郎 Shinjiro Masui	other	1.0M	¥670	-38.8%	¥1M ($7K)
2024-11-21	SELL	unknown	増井慎二郎 Shinjiro Masui	other	4.0M	¥670	-38.8%	¥4M ($28K)
2024-11-21	SELL	unknown	増井慎二郎 Shinjiro Masui	other	4.0M	¥670	-38.8%	¥1M ($9K)
2024-11-21	BUY	unknown	増井慎二郎 Shinjiro Masui	other	1.0M	¥670	+38.8%	¥677M ($4.4M)
2024-04-04	BUY	unknown	株式会社SBI証券 SBI SECURITIES Co.,Ltd.	other	74.0K	¥681	+36.6%	¥42M ($272K)
2024-03-06	BUY	Market Buy	株式会社SBI証券 SBI SECURITIES Co.,Ltd.	other	1.3M	¥717	+29.7%	¥5M ($30K)
2024-03-05	BUY	unknown	野村アセットマネジメント株式会社 Nomura Asset Management Co., Ltd.	other	546.3K	¥704	+32.1%	¥379M ($2.4M)
2024-03-05	SELL	unknown	ノムラインターナショナルピーエルシー NOMURA INTERNATIONAL PLC	other	118.3K	¥704	-32.1%	¥15M ($97K)
2024-03-05	SELL	unknown	野村證券株式会社 Nomura Securities Co.,Ltd.	other	98.7K	¥704	-32.1%	¥27M ($174K)
2024-02-07	BUY	Market Buy	株式会社SBI証券 SBI SECURITIES Co.,Ltd.	other	1.3M	¥901	+3.2%	¥2M ($12K)
2024-02-07	SELL	Market Buy	SBIアセットマネジメント株式会社 SBI Asset Management Co., Ltd.	other	0	¥901	-3.2%	¥44M ($285K)
2024-01-09	BUY	unknown	ノムラインターナショナルピーエルシー NOMURA INTERNATIONAL PLC	other	138.3K	¥845	+10.1%	¥117M ($754K)
2024-01-09	BUY	unknown	野村アセットマネジメント株式会社 Nomura Asset Management Co., Ltd.	other	804.1K	¥845	+10.1%	¥679M ($4.4M)
2024-01-09	BUY	unknown	野村證券株式会社 Nomura Securities Co.,Ltd.	other	136.4K	¥845	+10.1%	¥115M ($744K)
2023-12-22	SELL	unknown	SBIアセットマネジメント株式会社 SBI Asset Management Co., Ltd.	passive	49.5K	¥775	-20.0%	¥8M ($53K)
2023-12-22	SELL	unknown	株式会社SBI証券 SBI SECURITIES Co.,Ltd.	other	1.3M	¥775	-20.0%	¥3M ($21K)
2023-12-20	SELL	Market Buy	野村アセットマネジメント株式会社 Nomura Asset Management Co., Ltd.	other	804.1K	¥825	-12.7%	¥84M ($544K)
2023-12-20	SELL	Market Buy	ノムラインターナショナルピーエルシー NOMURA INTERNATIONAL PLC	other	118.0K	¥825	-12.7%	¥97M ($624K)
2023-12-20	BUY	Market Buy	野村證券株式会社 Nomura Securities Co.,Ltd.	other	138.5K	¥825	+12.7%	¥72M ($465K)
2023-11-22	BUY	unknown	SBIアセットマネジメント株式会社 SBI Asset Management Co., Ltd.	passive	60.0K	¥915	+1.6%	¥55M ($354K)
2023-11-22	BUY	unknown	株式会社SBI証券 SBI SECURITIES Co.,Ltd.	other	1.3M	¥915	+1.6%	¥1.2B ($7.5M)
2023-11-08	BUY	unknown	SBIアセットマネジメント株式会社 SBI Asset Management Co., Ltd.	passive	15.0K	¥935	-0.5%	¥995K ($6K)
2023-11-08	SELL	unknown	株式会社SBI証券 SBI SECURITIES Co.,Ltd.	other	0	¥935	+0.5%	¥3M ($19K)
2023-10-04	BUY	unknown	ノムラインターナショナルピーエルシー NOMURA INTERNATIONAL PLC	other	58.8K	¥753.75	+23.4%	¥44M ($286K)
2023-10-04	BUY	unknown	野村アセットマネジメント株式会社 Nomura Asset Management Co., Ltd.	other	226.4K	¥753.75	+23.4%	¥171M ($1.1M)
2023-10-04	BUY	unknown	野村證券株式会社 Nomura Securities Co.,Ltd.	other	12.5K	¥753.75	+23.4%	¥9M ($61K)
2023-09-07	BUY	Market Buy	SBIアセットマネジメント株式会社 SBI Asset Management Co., Ltd.	passive	13.8K	¥975	-4.6%	¥13M ($87K)
2023-09-07	BUY	Market Buy	株式会社SBI証券 SBI SECURITIES Co.,Ltd.	other	312.8K	¥975	-4.6%	¥519K ($3K)
2023-07-24	BUY	unknown	SBIアセットマネジメント株式会社 SBI Asset Management Co., Ltd.	passive	13.8K	¥1,041.25	-10.7%	¥14M ($93K)
2023-07-24	BUY	unknown	株式会社SBI証券 SBI SECURITIES Co.,Ltd.	other	311.9K	¥1,041.25	-10.7%	¥325M ($2.1M)
2023-06-06	BUY	unknown	野村アセットマネジメント株式会社 Nomura Asset Management Co., Ltd.	other	202.5K	¥1,457.5	-36.2%	¥291M ($1.9M)
2023-06-06	BUY	unknown	ノムラインターナショナルピーエルシー NOMURA INTERNATIONAL PLC	other	12.0K	¥1,457.5	-36.2%	¥7M ($45K)
2023-06-06	SELL	unknown	野村證券株式会社 Nomura Securities Co.,Ltd.	other	4.0K	¥1,457.5	+36.2%	¥3M ($20K)
2023-06-02	SELL	unknown	増井慎二郎 Shinjiro Masui	other	1.0M	¥1,387.5	+33.0%	¥76M ($490K)
2023-02-03	BUY	unknown	野村アセットマネジメント株式会社 Nomura Asset Management Co., Ltd.	other	278.0K	¥1,237.5	-24.9%	¥56M ($360K)
2023-02-03	SELL	unknown	ノムラインターナショナルピーエルシー NOMURA INTERNATIONAL PLC	other	7.5K	¥1,237.5	+24.9%	¥7M ($47K)
2023-02-03	SELL	unknown	野村證券株式会社 Nomura Securities Co.,Ltd.	other	6.4K	¥1,237.5	+24.9%	¥209M ($1.3M)
2023-01-18	BUY	unknown	野村アセットマネジメント株式会社 Nomura Asset Management Co., Ltd.	other	226.1K	¥1,177.5	-21.0%	¥266M ($1.7M)
2023-01-18	BUY	unknown	野村證券株式会社 Nomura Securities Co.,Ltd.	other	170.0K	¥1,177.5	-21.0%	¥200M ($1.3M)
2023-01-18	BUY	unknown	ノムラインターナショナルピーエルシー NOMURA INTERNATIONAL PLC	other	13.0K	¥1,177.5	-21.0%	¥15M ($99K)
2022-12-22	BUY	unknown	増井慎二郎 Shinjiro Masui	other	1.0M	¥981.25	-5.2%	¥1.0B ($6.5M)
2022-12-21	BUY	unknown	株式会社リンクアンドモチベーション Link and Motivation Inc.	corporate	2.7M	¥927.5	+0.3%	¥2.5B ($16.3M)

Frequently asked questions

Who has been buying OpenWork Inc. stock?: 8 distinct investors have filed 26 disclosed large-shareholding filings in OpenWork Inc. (5139), most recently on 2026-02-09. 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 OpenWork Inc. have?: OpenWork Inc. has 26 buy-side and 17 sell-side disclosures on record, covering ¥6.4B ($41.3M) in total reported value, spanning 2022-12-21 to 2026-02-09.
Where does StockDrifts get OpenWork 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 OpenWork Inc.. For how StockDrifts scores these disclosures, see the Japan insider signal tier research, or browse every Japanese stock we track.