Who has been buying mixi, Inc. stock?

5 distinct investors have filed 3 disclosed large-shareholding filings in mixi, Inc. (2121), most recently on 2025-05-22. 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 mixi, Inc. have?

mixi, Inc. has 3 buy-side and 10 sell-side disclosures on record, covering ¥14.5B ($93.3M) in total reported value, spanning 2021-08-31 to 2025-05-22.

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.

mixi, Inc. 2121

Company

株式会社ミクシィmixi, Inc.

Investors

Buys

Total Value

¥14.5B ($93.3M)

Avg Return

+1.29%

Last Filing

2025-05-22

mixi, Inc. (2121) has 3 disclosed large-shareholding filings and 10 disclosed disposals on record, filed by 5 distinct investors. Together those filings cover ¥14.5B ($93.3M) in reported transaction value. The earliest filing StockDrifts holds for mixi, Inc. is dated 2021-08-31; the most recent is 2025-05-22. Across these filings the average return since disclosure is +1.29%, 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
2025-05-22	BUY	negotiated	株式会社マーキュリー・リーフ Mercury Leaf Co., Ltd.	activist	2.0M	¥3,345	-	¥6.7B ($43.2M)
2025-05-22	BUY	negotiated	株式会社マーキュリー・スプラウト Mercury Sprout Co., Ltd.	activist	2.0M	¥3,345	-	¥6.7B ($43.2M)
2025-05-22	SELL	negotiated	笠原健治 Kenji Kasahara	activist	28.5M	¥3,345	-14.5%	¥13.4B ($86.4M)
2025-05-22	SELL	negotiated	笠原健治 Kenji Kasahara	activist	28.5M	¥3,345	-14.5%	¥13.4B ($86.4M)
2025-05-22	BUY	negotiated	株式会社マーキュリー・リーフ Mercury Leaf Co., Ltd.	activist	2.0M	¥3,345	-	¥6.7B ($43.2M)
2025-05-22	BUY	negotiated	株式会社マーキュリー・スプラウト Mercury Sprout Co., Ltd.	activist	2.0M	¥3,345	-	¥6.7B ($43.2M)
2024-09-04	SELL	unknown	ベイリー・ギフォード・オーバーシーズ・リミテッド Baillie Gifford Overseas Limited	other	373.8K	¥2,813	-36.1%	¥871M ($5.6M)
2024-09-04	BUY	unknown	ベイリー・ギフォード・アンド・カンパニー Baillie Gifford & Co	other	3.0M	¥2,813	+36.1%	¥8.3B ($53.6M)
2024-05-09	SELL	unknown	ベイリー・ギフォード・アンド・カンパニー Baillie Gifford & Co	other	3.5M	¥2,431	-57.5%	¥789M ($5.1M)
2024-05-09	SELL	unknown	ベイリー・ギフォード・オーバーシーズ・リミテッド Baillie Gifford Overseas Limited	other	684.1K	¥2,431	-57.5%	¥1.0B ($6.7M)
2024-03-27	BUY	Market Buy	笠原健治 Kenji Kasahara	activist	32.5M	¥2,720	+40.8%	¥3.9B ($24.8M)
2024-01-19	SELL	unknown	ベイリー・ギフォード・オーバーシーズ・リミテッド Baillie Gifford Overseas Limited	other	1.1M	¥2,509	-52.6%	¥296M ($1.9M)
2024-01-19	SELL	unknown	ベイリー・ギフォード・アンド・カンパニー Baillie Gifford & Co	other	3.9M	¥2,509	-52.6%	¥1.6B ($10.1M)
2023-06-06	SELL	unknown	ベイリー・ギフォード・アンド・カンパニー Baillie Gifford & Co	other	4.8M	¥2,749	-39.3%	¥1.6B ($10.4M)
2023-06-06	SELL	unknown	ベイリー・ギフォード・オーバーシーズ・リミテッド Baillie Gifford Overseas Limited	other	1.3M	¥2,749	-39.3%	¥903M ($5.8M)
2021-11-19	BUY	Market Buy	ベイリー・ギフォード・アンド・カンパニー Baillie Gifford & Co	other	5.3M	¥2,283	+67.8%	¥2.3B ($14.9M)
2021-11-19	SELL	Market Buy	ベイリー・ギフォード・オーバーシーズ・リミテッド Baillie Gifford Overseas Limited	other	1.6M	¥2,283	-67.8%	¥321M ($2.1M)
2021-08-31	BUY	negotiated	笠原健治 Kenji Kasahara	activist	33.0M	¥2,529	-	-

Frequently asked questions

Who has been buying mixi, Inc. stock?: 5 distinct investors have filed 3 disclosed large-shareholding filings in mixi, Inc. (2121), most recently on 2025-05-22. 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 mixi, Inc. have?: mixi, Inc. has 3 buy-side and 10 sell-side disclosures on record, covering ¥14.5B ($93.3M) in total reported value, spanning 2021-08-31 to 2025-05-22.
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.