Material event report (treasury share acquisition)

A later amendment corrects this filing, so the terms on this page may be out of date. See the latest version (2026-08-31) →

What happened

Sejin T S Co., Ltd. Material event report / Exchange disclosure obligation matter To the Financial Services Commission / Korea Exchange August 31, 2026 Company name: Sejin T S Co., Ltd. CEO: Kim In-sik Head office address: 51-43 Jimun-ro, Wongok-myeon, Anseong-si, Gyeonggi-do Phone: 031-650-3700; Website: http://www.sejints.co.kr Person responsible for preparation: (Title) Director, (Name) Park Yong-seon, Phone: 031-650-3700

Treasury share acquisition decision 1. Shares planned for acquisition (shares): Common stock 371,747; Other stock - 2. Planned acquisition amount (KRW): Common stock -; Other stock - 3. Expected acquisition period: Start date September 1, 2026; End date November 30, 2026 4. Expected holding period: Start date -; End date - 5. Purpose of acquisition: To stabilize the share price and enhance shareholder value 6. Acquisition method: Direct on-market acquisition through the Kosdaq market 7. Entrusted investment broker: Shinhan Securities Co., Ltd. 8. Treasury shares held before acquisition: Acquisition within the scope of distributable profit (shares) - Common stock 1,295,518, ratio 15.43%; Other stock -, ratio -. Other acquisitions (shares) - Common stock -, ratio -; Other stock -, ratio - 9. Acquisition decision date: August 31, 2026; independent (outside) director attendance* - present (persons) 1, absent (persons) 0; auditor (audit committee member other than an independent (outside) director) attendance - present 10. Daily purchase order quantity limit: Common stock 37,174; Other stock - * "Independent director" applies to listed companies and "outside director" to unlisted companies

11. Other matters for investors' reference - Item 1 above, "Shares planned for acquisition," was calculated based on the closing price (2,690 won) on the trading day before the board resolution date. - The Company plans to acquire treasury shares based on item 2 above, "Planned acquisition amount"; the actual acquisition amount and quantity of shares may change depending on future share-price movements. - Item 4 above, "Expected holding period," will be decided later after comprehensively considering relevant laws and regulations and the Company's management plans following the acquisition. - Item 10 above, "Daily purchase order quantity limit," was calculated as follows pursuant to Article 5-5, Paragraph 1, Item 2 of the Regulation on Issuance and Disclosure of Securities. Basis of calculation: the smaller of (i) the larger of [1] and [2] below, and (ii) [3] below: [1] 10% of the number of shares reported for acquisition: 37,174 common shares [2] 25% of the average daily trading volume over the 1 month preceding the day before the board resolution date: 25,082 common shares [3] 1% of total shares issued: 83,965 common shares

[Limit on the treasury-share acquisition amount] Item | Amount 1. Limit on distributable profit under the Commercial Act as of the end of the preceding fiscal year a. Net assets: 46,034,824,346 b. Capital stock: 4,198,296,500 c. Total capital reserves and earned surplus reserves accumulated through the preceding fiscal year: 13,054,933,755 d. Unrealized gains as prescribed by Presidential Decree: 1,097,981,405 Subtotal (a-b-c-d): 27,683,612,686 2. Treasury share acquisition amount since the end of the preceding fiscal year: 2,645,763,647 3. Dividend amount resolved at the ordinary general meeting since the end of the preceding fiscal year, and related earned surplus reserve: - 4. Quarterly/interim dividend amount resolved by the board since the end of the preceding fiscal year, and related earned surplus reserve: - 5. Trust contract amount: - 6. Acquisition cost of treasury shares disposed of since the end of the preceding fiscal year (moving-average method): - Limit on treasury share acquisition amount (1-2-3-4-5+6): 25,037,849,039

[Treasury shares held before the treasury share acquisition decision] (unit: shares) Acquisition method | Share type | Beginning quantity | Change: Acquired (+) / Disposed (-) / Retired (-) | Ending quantity | Remarks Direct acquisition - On-market direct acquisition, within distributable profit: Common stock | 100,904 | +700,805 | - | - | 801,709 | - On-market direct acquisition: Other stock | - | - | - | - | - | - Off-market direct acquisition: Common stock | - | - | - | - | - | - Off-market direct acquisition: Other stock | - | - | - | - | - | - Tender offer: Common stock | - | - | - | - | - | - Tender offer: Other stock | - | - | - | - | - | - Subtotal (a): Common stock | 100,904 | +700,805 | - | - | 801,709 | - Subtotal (a): Other stock | - | - | - | - | - | - Trust-contract acquisition - held by trustee: Common stock | - | - | - | - | - | - Trust-contract acquisition - held by trustee: Other stock | - | - | - | - | - | - Held in kind: Common stock | - | +493,809 | - | - | 493,809 | - Held in kind: Other stock | - | - | - | - | - | - Subtotal (b): Common stock | - | +493,809 | - | - | 493,809 | - Subtotal (b): Other stock | - | - | - | - | - | - Other acquisition (c): Common stock | - | - | - | - | - | - Other acquisition (c): Other stock | - | - | - | - | - | - Total (a+b+c): Common stock | 100,904 | +1,194,614 | - | - | 1,295,518 | - Total (a+b+c): Other stock | - | - | - | - | - | - - The beginning quantity above is based on the quantity of treasury shares the Company held before this treasury share acquisition decision, and the ending quantity is as of the disclosure document preparation date (August 31, 2026). - The on-market direct acquisition ending quantity of 801,709 shares above is the sum of the pre-existing holding of 100,904 shares and 700,805 shares acquired pursuant to the board resolution of July 31, 2026. - The ending quantity of 493,809 shares held in kind above are treasury shares acquired under the "Decision to enter into a treasury share acquisition trust contract" disclosed on July 1, 2026; following termination of the trust contract on July 31, 2026, these shares were transferred into the Company's own securities account.