[Amended] Material event report (rights offering)

What happened

STX / Material Event Report (Rights Offering Decision) / (2026.09.30)

Amendment Report September 30, 2026

1. Disclosure document being amended: Material Event Report 2. Original filing date of the disclosure document being amended: September 16, 2026

3. Amendment details Item: Reason for amendment / Before amendment / After amendment

1. Type and number of new shares: Adjustment of rehabilitation claims subject to debt-to-equity conversion following confirmation that certain rehabilitation claims did not exist, and court approval: 139,528,385 -> 139,507,887

20. Other matters for investment reference: - Debt-to-equity conversion amount: Reflecting adjustment of rehabilitation claims subject to debt-to-equity conversion: KRW 348,820,962,500 -> KRW 348,769,717,500 - Amount of debt reduced: KRW 348,821,005,887 -> KRW 348,769,758,729 - Total issued shares immediately after debt-to-equity conversion: Reflecting change in number of issued shares: 170,546,312 shares -> 170,525,814 shares - Capital stock immediately after debt-to-equity conversion: KRW 426,365,780,000 -> KRW 426,314,535,000

Selection process, transaction history, allotment details, etc. by third-party allottee: Change of creditor due to transfer of rehabilitation claim and court approval: Shinbo 2022-9th Securitization Specialty Co., Ltd. -> Korea Credit Guarantee Fund

Material Event Report / Matter Subject to KRX Reporting Obligation To: Financial Services Commission / Korea Exchange September 16, 2026 Company name: STX Corporation Representative Director: Park Sang-jun Head office address: 105 Jungang-daero, Seongsan-gu, Changwon-si, Gyeongsangnam-do (Phone) 02-316-9600 (Website) http://www.stx.co.kr Person responsible for preparation: (Title) Representative Director (Name) Park Sang-jun (Phone) 02-316-9600

Rights Offering Decision

1. Type and number of new shares: Common shares: 139,507,887; Other shares: - 2. Par value per share (KRW): 2,500 3. Total shares issued before the capital increase: Common shares: 31,017,927; Other shares: - 4. Purpose of fundraising: Facility funds (KRW): -; Business acquisition funds (KRW): -; Working capital (KRW): -; Debt repayment funds (KRW): -; Funds to acquire securities of other companies (KRW): -; Other funds (KRW): - 5. Capital increase method: Third-party allotment [Matters regarding other shares] Articles of incorporation basis: -; Content of the shares: -; Other: - 6. New share issue price: Common shares (KRW): 2,500; Other shares (KRW): - 7. Reference share price: Common shares (KRW): -; Other shares (KRW): - 7-1. Method of calculating the reference share price: Valuation of a stock for which no market price has been formed 7-2. Discount or premium rate to the reference share price (%): - 7-3. Basis for calculating the discount (premium) rate: - 8. Articles of incorporation basis for the third-party allotment: Article 9, Paragraph 2, Item 12 (Preemptive Rights) - Case of issuing new shares by converting rehabilitation security interests and rehabilitation claims into equity (newly established upon court approval of the rehabilitation plan) 9. Payment date: September 21, 2026 10. Dividend record start date for the new shares: January 1, 2026 11. Expected date of new share certificate delivery: - 12. Expected listing date of the new shares: October 23, 2026 13. Whether this constitutes a backdoor listing due to an in-kind contribution: No - Whether there is an in-kind contribution: No - Whether unlisted company shares are included among in-kind contribution assets: Not applicable - In-kind contribution value of shares to be paid in: In-kind contribution value (KRW): -; Ratio to the company's total assets for the most recent fiscal year (%): -; Number of shares to be paid in: - 14. Whether backdoor-listing requirements are met: Not applicable 15. Board resolution date (decision date): September 16, 2026; Attendance of independent (outside) directors: Present (persons): -; Absent (persons): -; Attendance of auditors (audit committee members): - 16. Whether a securities registration statement must be filed: No 17. If exempted from filing, the reason: Article 277 of the "Debtor Rehabilitation and Bankruptcy Act" provides that Article 119 (Registration of a Public Offering or Sale) of the "Financial Investment Services and Capital Markets Act" does not apply when a debtor company or a new company incorporated as a stock corporation issues shares or bonds. 18. Whether the subscription falls within a period when short selling is prohibited: No; Start date: -; End date: - 19. Whether subject to Fair Trade Commission reporting: Not applicable * The above "9. Payment date" is the effective date of the new shares. The above "15. Board resolution date (decision date)" is the date the rehabilitation plan was approved.

20. Other matters for investment reference: The Company is carrying out a debt-to-equity conversion of rehabilitation claims, including financial institution loan claims, trade claims, guarantee claims, indemnity claims, administrative fine claims, and related-party claims, under the rehabilitation plan approved by the Seoul Bankruptcy Court on September 16, 2026. This issuance of new shares is not a case where rehabilitation creditors newly pay in subscription money; rather, the effective date of the issued new shares substitutes for repayment of the relevant rehabilitation claims. There is no actual cash inflow. The amount obtained by multiplying the number of shares issued by the issue price per share is KRW 348,769,717,500, and the amount of debt reduced under the rehabilitation plan is KRW 348,769,758,729. Fractional shares of less than one share are handled with court approval in accordance with the rehabilitation plan. The new shares become effective on September 21, 2026, the date three business days after the rehabilitation plan approval decision date, and the receiver issues the new shares with court approval. Immediately after this debt-to-equity conversion, the total issued common shares are expected to be 170,525,814 shares and capital stock KRW 426,314,535,000. Thereafter, a capital reduction by consolidation and retirement at a ratio of 103:1 will be carried out in accordance with the approved rehabilitation plan. Shares converted from related-party claims will be retired in full without compensation. Debt-to-equity conversion arising from the future confirmation of unconfirmed or undetermined claims is not included in the number of shares issued this time, and when such claims are confirmed, they will be handled separately in accordance with the approved rehabilitation plan. The above decision date is the approval date of the rehabilitation plan that set the terms of this new share issuance, which the Company confirmed on the same day; it does not refer to the date an actual board meeting was held. New shares allotted to Korea Development Bank, which becomes the largest shareholder as a result of this debt-to-equity conversion, cannot be disposed of for six months from the listing date pursuant to Article 44 of the "KOSPI Market Listing Regulations," and will be placed under a six-month lock-up with the Korea Securities Depository. The number of shares issued, electronic registration, listing schedule, and other details may change depending on claim confirmation, treatment of fractional shares, court approval, and consultation with relevant authorities, and any changes will be disclosed through an amended filing.

When a listed company intends to issue a stock for which no market price has been formed on the securities market, the following information is additionally stated (unit: KRW, %):

Trading suspension information: Reference share price valuation method; Change ratio vs. closing price (B-A)/A*100; External valuation Trading suspension date: July 3, 2025; Last closing price before trading suspension (A): 3,530; Valuation method: -; Valuation amount (B): -; Whether performed: -; Valuation institution name: -

[Basis and purpose of the third-party allotment] Articles of incorporation provision serving as the basis for the third-party allotment: Articles of Incorporation, Article 9, Paragraph 2, Item 12, "Case of issuing new shares by converting rehabilitation security interests and rehabilitation claims into equity" Purpose of the third-party allotment: Debt-to-equity conversion of rehabilitation claims and improvement of financial structure under the approved rehabilitation plan

[Specific purpose of use of funds raised through the third-party allotment] [In the case of working capital/other funds] (unit: KRW) Fund use: Other funds; Details*: Debt-to-equity conversion; Planned amount of use by year: 2026: -; 2027: -; 2028 and after: -; Total: -

[Selection process, transaction history, and allotment details by third-party allottee]

Allottee: Korea Development Bank; Relationship with the company or largest shareholder: Rehabilitation creditor; Selection process: Debt-to-equity conversion of rehabilitation claim; Transactions within 6 months before/after the capital increase decision, and plans: -; Shares allotted: 50,370,158; Remarks: Six-month lock-up

Allottee: Seoul Guarantee Insurance Co., Ltd.; Relationship with the company or largest shareholder: Rehabilitation creditor; Selection process: Debt-to-equity conversion of rehabilitation claim; Transactions within 6 months before/after the capital increase decision, and plans: -; Shares allotted: 27,720,916; Remarks: -

Allottee: Woori Bank; Relationship with the company or largest shareholder: Rehabilitation creditor; Selection process: Debt-to-equity conversion of rehabilitation claim; Transactions within 6 months before/after the capital increase decision, and plans: -; Shares allotted: 25,262,488; Remarks: -

Allottee: NongHyup Bank; Relationship with the company or largest shareholder: Rehabilitation creditor; Selection process: Debt-to-equity conversion of rehabilitation claim; Transactions within 6 months before/after the capital increase decision, and plans: -; Shares allotted: 13,861,834; Remarks: -

Allottee: Shinhan Bank; Relationship with the company or largest shareholder: Rehabilitation creditor; Selection process: Debt-to-equity conversion of rehabilitation claim; Transactions within 6 months before/after the capital increase decision, and plans: -; Shares allotted: 9,906,558; Remarks: -

Allottee: STX Sunace Shipping Co., Ltd.; Relationship with the company or largest shareholder: Affiliate (rehabilitation creditor); Selection process: Debt-to-equity conversion of rehabilitation claim; Transactions within 6 months before/after the capital increase decision, and plans: -; Shares allotted: 5,295,485; Remarks: -

Allottee: Korea Credit Guarantee Fund; Relationship with the company or largest shareholder: Rehabilitation creditor; Selection process: Debt-to-equity conversion of rehabilitation claim; Transactions within 6 months before/after the capital increase decision, and plans: -; Shares allotted: 2,711,176; Remarks: -

Allottee: Gangnam Co., Ltd.; Relationship with the company or largest shareholder: Rehabilitation creditor; Selection process: Debt-to-equity conversion of rehabilitation claim; Transactions within 6 months before/after the capital increase decision, and plans: -; Shares allotted: 1,511,903; Remarks: -

Allottee: Kumho Development & Trading Co., Ltd.; Relationship with the company or largest shareholder: Rehabilitation creditor; Selection process: Debt-to-equity conversion of rehabilitation claim; Transactions within 6 months before/after the capital increase decision, and plans: -; Shares allotted: 1,148,294; Remarks: -

Allottee: Republic of Korea (competent authority: Financial Services Commission); Relationship with the company or largest shareholder: Rehabilitation creditor; Selection process: Debt-to-equity conversion of rehabilitation claim; Transactions within 6 months before/after the capital increase decision, and plans: -; Shares allotted: 717,131; Remarks: -

* Although there are many rehabilitation creditors subject to the third-party allotment, only the top 10 creditors are listed above.