Who has been buying COSMAX BTI stock?

1 distinct insiders have filed 26 disclosed insider purchases in COSMAX BTI (044820), most recently on 2026-05-26. 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 COSMAX BTI have?

COSMAX BTI has 26 buy-side and 0 sell-side disclosures on record, covering ₩2.4B ($1.7M) in total reported value, spanning 2025-01-01 to 2026-05-26.

Do insider buys in Korean stocks predict returns?

Not uniformly. StockDrifts analysed 170,720 share-count changes across 56,930 Korean regulatory filings using cross-sectional alpha at fixed forward horizons, and found returns concentrated in particular signal tiers rather than in insider buying generally.

COSMAX BTI 044820

Company

코스맥스비티아이COSMAX BTI

Insiders

Buys

Total Value

₩2.4B ($1.7M)

Avg Return

+20.82%

Last Filing

2026-05-26

COSMAX BTI (044820) has 26 disclosed insider purchases and 0 disclosed disposals on record, filed by 1 distinct insiders. Together those filings cover ₩2.4B ($1.7M) in reported transaction value. The earliest filing StockDrifts holds for COSMAX BTI is dated 2025-01-01; the most recent is 2026-05-26. Across these filings the average return since disclosure is +20.82%, measured from each filing date to the latest available close.

Price & insider activity (12 months)

Recent insider trades

Date	Type	Source	Insider	Position	Shares	Price at filing	Return	Value
2026-05-26	SELL	장외매도	서성석 Seongseok Seo	Chairman	-158.2K	₩18,960	+4.4%	₩3.0B ($2.1M)
2026-05-26	SELL	장외매도	서성석 Seongseok Seo	Chairman	-158.2K	₩18,960	+4.4%	₩3.0B ($2.1M)
2026-05-21	SELL	장외매도	서성석 Seongseok Seo	Chairman	-159.5K	₩18,810	+3.6%	₩3.0B ($2.1M)
2026-05-21	SELL	장외매도	서성석 Seongseok Seo	Chairman	-159.5K	₩18,810	+3.6%	₩3.0B ($2.1M)
2026-05-20	SELL	장외매도	서성석 Seongseok Seo	Chairman	-104.0K	₩19,320	+6.2%	₩2.0B ($1.4M)
2026-05-20	SELL	장외매도	서성석 Seongseok Seo	Chairman	-104.0K	₩19,320	+6.2%	₩2.0B ($1.4M)
2026-01-01	BUY	신규선임	서윤원 Seo Yoon-won	implementation	105	₩13,890	+2.6%	₩1M ($1K)
2025-11-03	BUY	Market Buy	서성석 Seongseok Seo	Chairman	3.2K	₩13,800	+3.3%	₩45M ($31K)
2025-10-31	BUY	Market Buy	서성석 Seongseok Seo	Chairman	9.4K	₩14,260	-0.1%	₩134M ($93K)
2025-10-30	BUY	Market Buy	서성석 Seongseok Seo	Chairman	11.3K	₩14,360	-0.8%	₩162M ($113K)
2025-10-29	BUY	Market Buy	서성석 Seongseok Seo	Chairman	11.0K	₩14,600	-2.4%	₩161M ($112K)
2025-10-28	BUY	Market Buy	서성석 Seongseok Seo	Chairman	5.1K	₩14,840	-4.0%	₩75M ($52K)
2025-10-27	BUY	Market Buy	서성석 Seongseok Seo	Chairman	21.2K	₩14,820	-3.9%	₩315M ($218K)
2025-10-24	BUY	Market Buy	서성석 Seongseok Seo	Chairman	231	₩14,890	-4.3%	₩3M ($2K)
2025-10-23	BUY	Market Buy	서성석 Seongseok Seo	Chairman	1.4K	₩14,880	-4.2%	₩21M ($15K)
2025-10-22	BUY	Market Buy	서성석 Seongseok Seo	Chairman	16.4K	₩15,560	-8.4%	₩255M ($177K)
2025-10-21	BUY	Market Buy	서성석 Seongseok Seo	Chairman	15.8K	₩15,160	-6.0%	₩240M ($167K)
2025-04-21	BUY	Market Buy	서성석 Seongseok Seo	Chairman	917	₩10,790	+32.1%	₩10M ($7K)
2025-04-17	BUY	Market Buy	서성석 Seongseok Seo	Chairman	58	₩10,640	+33.9%	₩617K ($429)
2025-04-15	BUY	Market Buy	서성석 Seongseok Seo	Chairman	9.7K	₩10,410	+36.9%	₩101M ($70K)
2025-04-14	BUY	Market Buy	서성석 Seongseok Seo	Chairman	2.5K	₩10,390	+37.1%	₩25M ($18K)
2025-04-11	BUY	Market Buy	서성석 Seongseok Seo	Chairman	8.2K	₩10,500	+35.7%	₩86M ($60K)
2025-04-10	BUY	Market Buy	서성석 Seongseok Seo	Chairman	8.5K	₩10,600	+34.4%	₩90M ($63K)
2025-04-09	BUY	Market Buy	서성석 Seongseok Seo	Chairman	3.7K	₩10,500	+35.7%	₩38M ($27K)
2025-04-08	BUY	Market Buy	서성석 Seongseok Seo	Chairman	5.7K	₩10,500	+35.7%	₩60M ($42K)
2025-04-07	BUY	Market Buy	서성석 Seongseok Seo	Chairman	9.7K	₩10,410	+36.9%	₩101M ($70K)
2025-04-04	BUY	Market Buy	서성석 Seongseok Seo	Chairman	1.0K	₩10,650	+33.8%	₩11M ($7K)
2025-04-03	BUY	Market Buy	서성석 Seongseok Seo	Chairman	8.2K	₩10,530	+35.3%	₩87M ($60K)
2025-04-02	BUY	Market Buy	서성석 Seongseok Seo	Chairman	19.7K	₩10,460	+36.2%	₩206M ($143K)
2025-04-01	BUY	Market Buy	서성석 Seongseok Seo	Chairman	4.1K	₩10,430	+36.6%	₩43M ($30K)
2025-03-31	BUY	Market Buy	서성석 Seongseok Seo	Chairman	4.5K	₩10,330	+38.0%	₩47M ($32K)
2025-03-28	BUY	Market Buy	서성석 Seongseok Seo	Chairman	7.3K	₩10,440	+36.5%	₩76M ($53K)
2025-03-27	BUY	Market Buy	서성석 Seongseok Seo	Chairman	2.2K	₩10,390	+37.1%	₩23M ($16K)
2025-01-01	BUY	신규선임	서미숙 Seo Mi-sook	Assistant Managing Director	356	₩8,490	+67.8%	₩3M ($2K)

Frequently asked questions

Who has been buying COSMAX BTI stock?: 1 distinct insiders have filed 26 disclosed insider purchases in COSMAX BTI (044820), most recently on 2026-05-26. 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 COSMAX BTI have?: COSMAX BTI has 26 buy-side and 0 sell-side disclosures on record, covering ₩2.4B ($1.7M) in total reported value, spanning 2025-01-01 to 2026-05-26.
Do insider buys in Korean stocks predict returns?: Not uniformly. StockDrifts analysed 170,720 share-count changes across 56,930 Korean regulatory filings using cross-sectional alpha at fixed forward horizons, and found returns concentrated in particular signal tiers rather than in insider buying generally.

More on this data

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