[Amended] Material event report (bonus issue)

What happened

Material Event Report (Bonus Issue Decision) 6.0 Alteogen Inc.

Amendment Report (Disclosure) Date: July 20, 2026

1. Disclosure document being amended: Material Event Report (Bonus Issue Decision) 2. Original filing date of the disclosure document being amended: July 16, 2026 3. Amended items: Item: 8. Expected listing date of new shares - Reason for amendment: schedule change following consultation with relevant authorities. Before: August 20, 2026. After: August 26, 2026.

Material Event Report / Matter Subject to Exchange Disclosure Obligation To: Financial Services Commission / Korea Exchange Date: July 16, 2026 Company name: Alteogen Inc. Representative director: Jeon Tae-yeon Head office address: 62 Yuseongdae-ro 1628beon-gil, Yuseong-gu, Daejeon (Jeonmin-dong) Phone: 042-384-8780 Website: http://www.alteogen.com Preparer: Executive Vice President of Finance & Accounting Kim Hang-yeon, Phone: 042-384-8780

Bonus Issue Decision

1. Type and number of new shares: Common shares (shares) 16,068,790; Other shares (shares) 122,037 2. Par value per share (KRW): 500 3. Total shares issued before the capital increase: Common shares (shares) 53,586,343; Other shares (shares) 406,793 4. New share allotment record date: August 6, 2026 5. Number of new shares allotted per existing share: Common shares 0.3; Other shares 0.3 6. Dividend accrual date for new shares: January 1, 2026 7. Expected date of delivery of new share certificates: none 8. Expected listing date of new shares: August 26, 2026 9. Board resolution date (decision date): July 16, 2026 - Outside directors in attendance: 4; absent: none - Attendance of auditor (audit committee member): present 10. Other material matters for investors' reference: 1) Bonus issue allotment details [Unit: shares] - Category / Shares issued before the bonus issue / Bonus issue allotment / Shares issued after the bonus issue: Common shares (excluding treasury shares): 53,562,635 / 16,068,790 / 69,631,425 Common shares (treasury shares): 23,708 / none / 23,708 Redeemable convertible preferred shares: 406,793 / 122,037 / 528,830 Total: 53,993,136 / 16,190,827 / 70,183,963 2) New share allotment and handling of fractional shares: new shares will be allotted at a ratio of 0.3 shares (30%) per share held to shareholders (excluding treasury shares) recorded in the register as of the allotment record date; fractional shares of less than one share will be paid in cash based on the closing price on the first day of listing of the new shares. 3) Source of funds for the new shares: paid-in capital in excess of par, KRW 8,095,413,500 4) Total number of shares not entitled to the new-share allotment: 23,708 treasury common shares 5) Item 7, "Expected date of delivery of new share certificates," is omitted as not applicable under the electronic securities registration system. 6) Other incidental matters concerning the new share issuance are delegated to the representative director, and the above schedule may change through consultation with relevant authorities.

[Matters concerning other-class shares] Articles-of-incorporation basis: Article 9 of the Articles of Incorporation ("Types of Shares") Content of the shares: Series 5 registered redeemable convertible preferred shares Other: Par value KRW 500; Shares issued: 434,848; Shares currently outstanding: 406,793