Treasury Stock Trust Contract Terminated Early — Acquisition Complete — Dongjin Semichem

Summary

Dongjin Semichem has terminated its ₩10 billion treasury stock acquisition trust with Daishin Securities effective August 31, 2026, ahead of the original February 2027 maturity, citing completion of the buyback program. Under the trust, the company accumulated 234,800 common shares (0.46% of total shares) after purchasing 649,700 shares and disposing of 414,900 shares in the open market. The 234,800 remaining trust-held shares will be transferred to the company's own corporate securities account as directly held treasury stock — they are not being cancelled. The board resolution approving the early termination was passed on the same day, August 31, 2026, with one independent director in attendance.

Historical Impact

3 past Major Event Report · ≈ 8-K events at Dongjin Semichem

Median +5d

-0.77%

Range

-6.52% to +3.07%

Positive outcomes

1/3

Filed	P₀	P₊₅	+5d
Jul 31, 2026	₩39,150	₩38,850	-0.77%
Apr 13, 2026	₩52,200	₩53,800	+3.07%

Full Translation

Material Report (Decision to Terminate Treasury Stock Acquisition Trust Contract) To: Financial Services Commission / Korea Exchange Date: August 31, 2026 Company: Dongjin Semichem Co., Ltd. CEO: Lee Jun-hyuk Headquarters: 644 Baekbeom-ro, Seo-gu, Incheon Phone: 032-578-5091 Website: https://www.dongjin.com Prepared by: Executive Director Jeong Seong-yeop (02-325-9451) [Decision to Terminate Treasury Stock Acquisition Trust Contract] 1. Contract Amount (KRW) Before termination: 10,000,000,000 After termination: — 2. Contract Period Before Termination Start date: August 3, 2026 End date: February 2, 2027 3. Purpose of Termination Early termination upon completion of treasury stock acquisition 4. Terminating Institution Daishin Securities Co., Ltd. 5. Scheduled Termination Date August 31, 2026 6. Treasury Stock Holdings Before Termination Acquired within distributable profit limit: Common shares: 234,800 shares (0.46%) Other shares: — Other acquisitions: Common shares: — Other shares: — 7. Board Resolution Date: August 31, 2026 Independent (outside) director attendance: 1 present, 0 absent Audit committee attendance: Present 8. Shares Subject to Termination Common shares: 234,800 Other shares: — 9. Additional Information for Investment Decisions The 234,800 shares listed under item 8 represent treasury shares to be returned from the trust account. These shares will be deposited into the company's own corporate securities account, whereupon the company will hold the treasury stock directly. [Treasury Stock Holdings Before Trust Contract Termination] (Unit: shares) Acquisition Method | Share Type | Beginning Balance | Acquired (+) | Disposed (−) | Cancelled (−) | Ending Balance | Notes Direct acquisition (within distributable profit limit): On-market direct: Common — / — / — / — / — Off-market direct: Common — / — / — / — / — Tender offer: Common — / — / — / — / — Subtotal (a): Common — / — / — / — / — Trust contract acquisition: Trustee-held: Common — / 649,700 / — / 414,900 / 234,800 Physically held: Common — / — / — / — / — Subtotal (b): Common — / 649,700 / — / 414,900 / 234,800 Other acquisition (c): Common 29,468 / — / — / 29,468* / — Total (a+b+c): Common 29,468 / 649,700 / — / 444,368 / 234,800 Note 1: 'Beginning balance' reflects holdings as of the start of the current fiscal year (January 1, 2026); 'ending balance' reflects holdings as of the disclosure preparation date (August 31, 2026).