Who has been buying HPC SYSTEMS Inc. stock?

11 distinct investors have filed 13 disclosed large-shareholding filings in HPC SYSTEMS Inc. (6597), most recently on 2026-03-06. 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 HPC SYSTEMS Inc. have?

HPC SYSTEMS Inc. has 13 buy-side and 5 sell-side disclosures on record, covering ¥3.1B ($19.8M) in total reported value, spanning 2021-09-22 to 2026-03-06.

Where does StockDrifts get HPC SYSTEMS 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.

HPC SYSTEMS Inc. 6597

Company

HPCシステムズ株式会社HPC SYSTEMS Inc.

Investors

Buys

Total Value

¥3.1B ($19.8M)

Avg Return

+29.87%

Last Filing

2026-03-06

HPC SYSTEMS Inc. (6597) has 13 disclosed large-shareholding filings and 5 disclosed disposals on record, filed by 11 distinct investors. Together those filings cover ¥3.1B ($19.8M) in reported transaction value. The earliest filing StockDrifts holds for HPC SYSTEMS Inc. is dated 2021-09-22; the most recent is 2026-03-06. 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 +29.87%, 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
2026-03-06	BUY	unknown	株式会社りそな銀行 Resona Bank, Limited.	other	260.0K	¥1,863	+42.1%	¥484M ($3.1M)
2025-11-25	SELL	negotiated	ナラサキ産業株式会社 NARASAKI SANGYO CO., LTD.	strategic	279.0K	¥1,705	-55.3%	¥32M ($207K)
2025-11-21	SELL	unknown	菱洋エレクトロ株式会社 RYOYO ELECTRO CORPORATION	other	304.8K	¥1,757	-50.7%	¥582M ($3.8M)
2025-02-07	SELL	unknown	アセットマネジメントOne株式会社 Asset Management One Co., Ltd.	other	132.4K	¥1,139	-132.5%	¥114M ($737K)
2024-09-06	BUY	unknown	みずほ証券株式会社 Mizuho Securities Co., Ltd.	other	1.5K	¥1,266	+109.2%	¥111M ($716K)
2024-09-06	BUY	unknown	アセットマネジメントOne株式会社 Asset Management One Co., Ltd.	other	232.5K	¥1,266	+109.2%	¥291M ($1.9M)
2024-07-22	BUY	Market Buy	みずほ証券株式会社 Mizuho Securities Co., Ltd.	other	43.0K	¥1,198	+121.0%	¥52M ($332K)
2024-07-22	BUY	Market Buy	アセットマネジメントOne株式会社 Asset Management One Co., Ltd.	other	234.3K	¥1,198	+121.0%	¥2M ($13K)
2023-05-10	BUY	Market Buy	SBIアセットマネジメント株式会社 SBI Asset Management Co., Ltd.	passive	66.6K	¥2,119	+25.0%	¥141M ($910K)
2023-05-10	SELL	Market Buy	株式会社SBI証券 SBI SECURITIES Co.,Ltd.	other	40.7K	¥2,119	-25.0%	¥3M ($18K)
2023-05-10	BUY	Market Buy	レオス・キャピタルワークス株式会社 RHEOS CAPITAL WORKS Inc.	passive	117.6K	¥2,119	+25.0%	¥249M ($1.6M)
2023-03-23	BUY	Market Buy	SBIアセットマネジメント株式会社 SBI Asset Management Co., Ltd.	passive	66.6K	¥2,025	+30.8%	¥135M ($870K)
2023-03-23	BUY	Market Buy	株式会社SBI証券 SBI SECURITIES Co.,Ltd.	other	41.9K	¥2,025	+30.8%	¥85M ($547K)
2023-03-23	BUY	Market Buy	レオス・キャピタルワークス株式会社 RHEOS CAPITAL WORKS Inc.	passive	117.6K	¥2,025	+30.8%	¥238M ($1.5M)
2022-08-22	BUY	Market Buy	山上豊 Yutaka Yamagami	passive	188.9K	¥2,645	+0.1%	¥69M ($447K)
2022-08-22	SELL	Market Buy	山上豊 Yutaka Yamagami	passive	188.9K	¥2,645	-0.1%	¥69M ($447K)
2022-07-29	BUY	Market Buy	山上豊 Yutaka Yamagami	passive	214.9K	¥3,235	-18.1%	¥695M ($4.5M)
2021-12-06	BUY	Market Buy	日興アセットマネジメント株式会社 Nikko Asset Management Co.,Ltd.	other	172.3K	¥2,708	-2.2%	¥461M ($3.0M)
2021-12-06	BUY	Market Buy	三井住友トラスト・アセットマネジメント株式会社 Sumitomo Mitsui Trust Asset Management Co.,Ltd.	other	25.4K	¥2,708	-2.2%	¥16M ($104K)
2021-10-22	BUY	unknown	アセットマネジメントOne株式会社 Asset Management One Co., Ltd.	other	227.0K	¥3,670	-27.9%	¥833M ($5.4M)
2021-09-22	BUY	unknown	日興アセットマネジメント株式会社 Nikko Asset Management Co.,Ltd.	other	215.7K	¥3,210	-17.5%	¥692M ($4.5M)
2021-09-22	BUY	unknown	三井住友トラスト・アセットマネジメント株式会社 Sumitomo Mitsui Trust Asset Management Co.,Ltd.	other	19.6K	¥3,210	-17.5%	¥63M ($406K)

Frequently asked questions

Who has been buying HPC SYSTEMS Inc. stock?: 11 distinct investors have filed 13 disclosed large-shareholding filings in HPC SYSTEMS Inc. (6597), most recently on 2026-03-06. 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 HPC SYSTEMS Inc. have?: HPC SYSTEMS Inc. has 13 buy-side and 5 sell-side disclosures on record, covering ¥3.1B ($19.8M) in total reported value, spanning 2021-09-22 to 2026-03-06.
Where does StockDrifts get HPC SYSTEMS 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 HPC SYSTEMS Inc.. For how StockDrifts scores these disclosures, see the Japan insider signal tier research, or browse every Japanese stock we track.