[Amended] Supply contract signed (subsidiary)

What happened

Dong-A Socio Holdings / Supply Contract Signed / (2026.09.30) Supply Contract Signed

Amendment Report Amendment date: 2026-09-30

1. Disclosure document being amended: Supply Contract Signed (Subsidiary's Material Management Matter) 2. Filing date of the disclosure document being amended: April 20, 2026 3. Reason for amendment: Extension of the non-disclosure deadline under an agreement with the counterparty

4. Amendment details Item: Before amendment -> After amendment Subsidiary name: STGenBio Co., Ltd. -> BTGen Co., Ltd. 9. Other matters important to investment judgment: Before amendment - The scheduled contract end date is September 30, 2026. The non-disclosure deadline is October 7, 2029. -> After amendment: (updated wording, see below)

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Supply Contract Signed Report on a material management matter of the subsidiary BTGen Co., Ltd.

1. Type of sales/supply contract: Other sales/supply contract - Contract name: Pharmaceutical contract manufacturing agreement

2. Contract details: Contract amount (KRW): 7,542,000,000; Most recent revenue (KRW): 103,733,752,800; Ratio to revenue (%): 7.3; Whether a large corporation: Not applicable

3. Counterparty: -; Relationship with the company: -

4. Sales/supply region: Domestic

5. Contract period: Start date 2026-04-17; End date 2026-09-30

6. Key contract terms: Down payment/advance payment: Yes; Payment terms: Paid in installments within the contract period upon completion of tasks requested by the client

7. Contract (order) date: 2026-04-17

8. Non-disclosure details: Reason for non-disclosure: Maintenance of business confidentiality; Non-disclosure deadline: 2029-10-07

9. Other matters important to investment judgment: - The above contract amount is the total contract amount, and the advance payment is KRW 3,016,800 thousand. - The above most recent revenue is based on STGenBio's 2025 separate (non-consolidated) financial statements (as stated in the filing). - The above contract end date may change by agreement between the two parties. - The non-disclosure deadline is October 7, 2029.

Related disclosures: -