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COSMAX BTI

Chairman & Major Shareholder Seo Seong-seok Sells 843,340 Shares (8.78%p) in Block Trades, Ownership Plunges to 13.83%, Raising Governance Concerns and Downside Pressure on Stock


  • Seo Seong-seok, Chairman and largest shareholder of COSMAX BTI, sold a total of 843,340 common shares (38.8% of his previous holdings) via block trades between May 20 and May 26, 2026.
  • The average sale price was 18,992 won per share, slightly above the closing price of 18,490 won on the report reference date (May 27).
  • The buyers were two entities, BJH and SSY, with equal amounts and prices. The sales were pre-planned on April 3.
  • As a result, Seo's stake dropped sharply from 22.61% to 13.83%, a decline of 8.78 percentage points, maintaining his position as top shareholder but raising concerns over management stability.
  • Such a massive insider sell-off signals potential lack of confidence and may exert downward pressure on the stock price. Investors should monitor further stake changes.
  • [AI Comprehensive Analysis]The block sale by the largest shareholder is likely interpreted as a lack of confidence by management, putting downside pressure on the stock in the short term. Although the off-market block deals minimized market impact, the remaining stake of only 13.83% is relatively low, leaving room for further sales and uncertainty.

KOSPI Filing Information


  • Filing: Report on Ownership of Specific Securities by Executives and Major Shareholders
  • Company: COSMAX BTI (044820)
  • Submission: Seo Seong-seok
  • Receipt: 05-28-2026