Material event report (equity acquisition)

What happened

Decision to acquire shares and equity securities of another company 6.1 Doosan Corporation

Material event report / Matter subject to exchange reporting obligation To: Financial Services Commission / Korea Exchange July 31, 2026 Company name: Doosan Corporation Representative directors: Park Jeong-won, Kim Min-cheol, Yoo Seung-woo Head office address: Doosan Tower, 275 Jangchungdan-ro, Jung-gu, Seoul (Phone) 02-3398-0114 (Website) http://www.doosancorp.co.kr Person responsible for preparation: (Title) Executive Vice President; (Name) Eun Hong-gi; (Phone) 02-3398-2039

Decision to acquire shares and equity securities of another company

1. Issuing company Company name: SK Siltron Co., Ltd. (SK Siltron Co., Ltd.) Nationality: Republic of Korea Representative: Jeong Gwang-jin Capital (KRW): 33,511,675,000 Relationship with the Company: - Total shares issued: 67,023,350 Main business: Manufacture of silicon wafers for the electronics industry Whether new shares were acquired via third-party allotment within the last 6 months: No

2. Acquisition details Number of shares acquired: 47,322,350 Acquisition amount (KRW) (A): 2,300,000,000,000 Total assets (KRW) (B): 32,927,788,134,642 Ratio to total assets (%) (A/B): 6.98 Equity capital (KRW) (C): 12,234,320,653,865 Ratio to equity capital (%) (A/C): 18.80

3. Number of shares held and ownership ratio after acquisition Shares held: 47,322,350 Ownership ratio (%): 70.61

4. Purpose of acquisition: Securing a mid-to-long-term growth foundation through business diversification

5. Expected acquisition date: January 31, 2027

6. Counterparty Company name (person): SK Inc. Capital (KRW): 16,143,092,800 Main business: Holding company and IT services business Head office address: 26 Jongno (Seorin-dong), Jongno-gu, Seoul Relationship with the Company: -

7. Payment of transaction consideration 1) Payment method: Cash payment 2) Payment timing: The deposit (10%) will be paid immediately after execution of the agreement, and the balance (90%) is expected to be paid on the transaction closing date. 3) Funding method: The Company's own funds and borrowings

8. Matters concerning external valuation Whether there was an external valuation: Yes Basis and reason: 1. Basis: Prepared for use as an attachment to the material event report submitted to the Financial Services Commission under Article 161 of the Financial Investment Services and Capital Markets Act and Article 171 of its Enforcement Decree. 2. Reason: To provide reference material for assessing the appropriateness of the acquisition price in acquiring shares of the issuing company, and for use as an attachment to the material event report submitted by the Company under the Financial Investment Services and Capital Markets Act Name of external valuation institution: Anjin Accounting Corporation External valuation period: January 23, 2026 - July 31, 2026 External valuation opinion: According to the valuer's assessment, as of the valuation reference date (March 31, 2026), the value of the shares to be acquired is calculated to range from KRW 2,089,897 million to KRW 2,473,638 million. Accordingly, the acquisition amount of KRW 2,300,000 million for the shares to be acquired, as agreed between the transaction parties, is judged to be appropriate when considering the above valuation range as of the valuation reference date.

9. Board resolution date (decision date): July 31, 2026 Independent (outside) director* attendance: Present (number): 4; Absent (number): - Attendance of statutory auditor (audit committee member who is not an independent (outside) director*): -

10. Whether this constitutes a backdoor listing: No Plans for a third-party-allotted capital increase, etc. within the next 6 months: No

11. Whether the issuing company (the other company) meets the requirements for a backdoor listing: No

12. Whether subject to Fair Trade Commission reporting: Not applicable

13. Whether a put option or similar contract was entered into: No Contract details: -

* Applies to independent directors for listed companies and outside directors for unlisted companies

14. Future plans for corporate restructuring 1) The Company does not plan a separate listing of the issuing company after acquiring its equity. 2) Regarding the issuing company's subsidiaries, etc. engaged in the silicon carbide (SiC) business (including SK Siltron USA, Inc. and affiliates directly or indirectly controlled by it), the issuing company's board of directors approved liquidation effective 2026. 7. 16., and after execution of the share purchase agreement, specific liquidation procedures will proceed following discussions by a liquidation council formed with the Company's participation, among others. 3) After executing the share purchase agreement, the Company will operate an acquisition team to prepare for post-merger integration (PMI) activities covering organization, business, and other matters, and plans to review various restructuring options, including mergers, to achieve efficient post-acquisition operations and synergies; specific matters that are determined in the future will be disclosed in accordance with disclosure regulations, etc.

15. Other matters for reference in investment decisions 1) This transaction concerns the acquisition by the Company, as buyer, of a 70.61% equity stake in the issuing company from SK Inc., as seller, under a share purchase agreement between the two parties (the "Transaction"). For reference, separately from the Transaction, the Company plans to hold separate discussions with the relevant counterparty with a view to acquiring the issuing company's remaining equity stake (29.39%); specific matters that are determined in the future will be disclosed in accordance with disclosure regulations, etc. 2) The capital and total shares issued of "1. Issuing company" above are as of the disclosure filing date. 3) The total assets and equity capital in "2. Acquisition details" above are stated based on the consolidated financial statements as of the end of the most recent fiscal year (December 31, 2025). 4) The acquisition amount in "2. Acquisition details" above is stated based on the basic purchase price under the share purchase agreement for the Transaction, and may be adjusted to reflect adjustment items arising and confirmed up to the transaction closing date. Separately, an additional excess-profit sharing amount may be paid to the seller as described below, conditional on the issuing company's future business performance.

Excess-profit sharing amount -- Reason for payment / Payment amount: - From 2027 to 2034, if the issuing company exceeds its annual EBITDA threshold amount for each year, including satisfying detailed conditions*: EBITDA threshold amount (Unit: KRW trillion) -- 2027: 0.89; 2028: 1.00; 2029: 1.10; 2030: 1.20; 2031: 1.30; 2032: 1.40; 2033: 1.55; 2034: 1.70. Amount calculated by applying the target shares' ownership ratio (70.61%) to 40% of the excess amount. - From 2026 to the end of June 2029, upon the issuing company's completion of quality certification of a specific item for a specific customer: an amount calculated by applying the target shares' ownership ratio to KRW 25 billion per item (4 items in total). - Where proceeds from the sale of all assets held by SK Siltron USA, Inc. and other U.S. subsidiaries of the issuing company scheduled for liquidation under the share purchase agreement, and from the sale of other assets scheduled for sale under the share purchase agreement, each exceed their book value: an amount calculated by applying the target shares' ownership ratio to the disposal gain.

5) The acquisition amount, ratio to total assets (%), and ratio to equity capital (%) in "2. Acquisition details" above are stated based on the basic purchase price under the share purchase agreement. If the planned future acquisition of the issuing company's remaining equity stake (29.39%) and the excess-profit sharing described in 4) above are included, the acquisition amount could be 10% or more of total assets. 6) The "5. Expected acquisition date" above is the expected transaction closing date, premised on satisfaction of the conditions precedent under the share purchase agreement, including approval by relevant authorities, and may change depending on discussions with the seller, etc. 7) If there is any confirmation or change relating to this disclosure, it will be re-disclosed through a related disclosure, etc. 8) The Company has delegated to its representative director matters not specified by the board of directors in connection with this matter and other detailed administrative handling. 9) This disclosure is the confirmed disclosure relating to the "Response to Rumor or Report (unconfirmed)" dated June 15, 2026. 10) The Company's audit committee is composed entirely of independent directors. 11) The "Summary financial status of the issuing company" below is based on the consolidated financial statements for the current year (2025), the prior year (2024), and the year before the prior year (2023).

Related disclosures: Doosan / Response to rumor or report (unconfirmed) / 2025.10.02; Doosan / Response to rumor or report (unconfirmed) / 2025.10.31; Doosan / Response to rumor or report (unconfirmed) / 2025.12.17; Doosan / Response to rumor or report (unconfirmed) / 2026.03.16; Doosan / Response to rumor or report (unconfirmed) / 2026.06.15

[Summary financial status of the issuing company] (Unit: KRW thousand) Category / Total assets / Total liabilities / Total equity / Capital / Revenue / Net income / Audit opinion / External auditor Current year: 5,594,810,389 / 3,661,379,237 / 1,933,431,152 / 33,511,675 / 2,057,485,935 / -293,620,586 / Appropriate / Hanyoung Accounting Corporation Prior year: 6,178,784,809 / 3,935,552,907 / 2,243,231,902 / 33,511,675 / 2,126,812,964 / 248,048,989 / Appropriate / Hanyoung Accounting Corporation Year before prior year: 5,451,562,679 / 3,498,152,575 / 1,953,410,104 / 33,511,675 / 2,025,590,278 / 233,991,597 / Appropriate / Hanyoung Accounting Corporation

[Matters concerning borrowings] (Unit: KRW) Lender / Loan amount / Loan period / Collateral assets / Note: -; -; -; -; - Subtotal: -; -; -; -

Note: The Company plans to fund the acquisition price from its own funds and borrowings, but the specific details regarding the borrowing have not yet been finalized; the Company will amend and disclose the above related matters once they are finalized.