Large Shareholding Report: Collateral Pledge Ratio Change by Special Related Party

LARGE SHAREHOLDING REPORT (General Form) Version 6.0 LB Semicon Co., Ltd. Large Shareholding Report (General Form: Report under Article 147 of the Financial Investment Services and Capital Markets Act, filed for the purpose of 'influencing management control') To: Financial Services Commission Date obligation arose: May 11, 2026 To: Korea Exchange Report preparation date: May 18, 2026 Reporter: Koo Bon-cheon — SUMMARY INFORMATION — Issuing Company: LB Semicon Co., Ltd. Relationship to Issuing Company: Largest Shareholder Report Type: Amendment (Change) Shares Held (Number / Ratio): Previous report: 15,819,778 shares / 27.24% This report: 15,819,778 shares / 27.24% Shares Subject to Major Contracts (Number / Ratio): Previous report: 1,082,214 shares / 1.86% This report: 1,909,608 shares / 3.29% Voting Rights Held: — / — (both periods) Voting Rights Subject to Major Contracts: — / — (both periods) Reason for Report: Change in collateral pledge ratio attributable to a special related party ※ The reporter certifies that the shareholding status of the reporter and all special related parties as of the report preparation date has been accurately prepared in accordance with relevant laws and disclosure requirements, and that there are no false statements or material omissions. — PART 1: OVERVIEW OF THE REPORT — 1. Information on the Issuing Company Company Name: LB Semicon Co., Ltd. Company Code: 061970 Corporate Classification: KOSDAQ-listed corporation Total Voting Shares Issued: 58,083,006 shares 2. Information on the Large Shareholder A. Reporter (1) Reporter Overview Report Type: Amendment Joint Filing: No Reporter Classification: Individual (Domestic) Nationality: Republic of Korea Name (Korean): 구본천 Name (Hanja/English): 具本天 Address (district level): Cheongdam-dong, Gangnam-gu, Seoul Date of Birth: June 5, 1964 (640511) Occupation: Registered Director, LB Semicon Co., Ltd. Relationship to Issuing Company: Registered Director Contact Information: Affiliated Company: LB Semicon Co., Ltd. Department: Planning Team Title: Manager (책임) Phone: 031-68-XXXXXX Name: Han Sun-kwang Fax: 031-68-XXXXXX Email: XXXXXX@lbsemicon.com (2) Specific Details on Reporter (applicable to corporations/associations only): All fields — N/A (individual reporter) B. Special Related Parties (1) Overview of Special Related Parties No. | Name | Type | Relationship to Reporter | DOB/Business Reg. | Nationality | Address | Occupation | Relation to Issuing Co. 1 | LB Co., Ltd. (㈜엘비) | Domestic Corp. | Affiliated company | 120-87-62897 | Korea | Daechi-dong, Gangnam-gu, Seoul | Holding company | Affiliated company 2 | Koo Bon-wan | Individual (Dom.)| Family/relative | 661030 | Korea | Hannam-dong, Gangnam-gu, Seoul | — | Shareholder 3 | Koo Sang-mo | Individual (Dom.)| Family/relative | 010317 | Korea | Cheongdam-dong, Gangnam-gu, Seoul | — | Shareholder 4 | Koo In-mo | Individual (Dom.)| Family/relative | 030830 | Korea | Hannam-dong, Yongsan-gu, Seoul | — | Shareholder 5 | Lee Seong-eun | Individual (Dom.)| Family/relative | 690330 | Korea | Cheongdam-dong, Gangnam-gu, Seoul | — | Shareholder 6 | Koo Hye-ran | Individual (Dom.)| Family/relative | 601231 | Korea | Daechi-dong, Gangnam-gu, Seoul | — | Shareholder 7 | Park Seong-eun | Individual (Dom.)| Family/relative | 691014 | Korea | Hannam-dong, Yongsan-gu, Seoul | — | Shareholder 8 | Koo Hye-seon | Individual (Dom.)| Family/relative | 620505 | Korea | Bundang-gu, Seongnam, Gyeonggi | — | Shareholder 9 | Koo Jin-yeong | Individual (Dom.)| Family/relative | 940305 | Korea | Cheongdam-dong, Gangnam-gu, Seoul | — | Shareholder 10 | Koo Ha-yeong | Individual (Dom.)| Family/relative | 960917 | Korea | Cheongdam-dong, Gangnam-gu, Seoul | — | Shareholder 11 | Sim Yun-seon | Individual (Dom.)| Family/relative | 831219 | Korea | Daechi-dong, Gangnam-gu, Seoul | — | Shareholder 12 | Jang Yun-jeong | Individual (Dom.)| Family/relative | 881214 | Korea | Bundang-gu, Seongnam, Gyeonggi | — | Shareholder 13 | Koo Do-yeon | Individual (Dom.)| Family/relative | 120629 | Korea | Hannam-dong, Yongsan-gu, Seoul | — | Shareholder (2) Specific Details on Special Related Parties (corporate entities) ① LB Co., Ltd. (㈜엘비) [Unit: KRW millions] Legal form: Corporation Total assets (consolidated): 227,853 Total liabilities: 21,399 Total equity: 161,049 Paid-in capital: 1,000 Representative director(s): Koo Bon-cheon, Kim Yun-kwon Decision-making body: Shareholders' meeting and Board of Directors Largest shareholder: Koo Bon-cheon Largest shareholder stake: 28.27% ※ Based on consolidated audit report (December 2025) C. Collective Investment Manager: N/A (no collective investment vehicle among reporter or related parties) 3. Number and Ratio of Shares Held Previous report (Feb. 10, 2026): Koo Bon-cheon + 13 related parties | 15,819,778 shares | 27.24% | Voting shares: 15,819,778 | 27.24% This report (May 18, 2026): Koo Bon-cheon + 13 related parties | 15,819,778 shares | 27.24% | Voting shares: 15,819,778 | 27.24% Change: 0 shares | 0% Total voting shares issued: 58,083,006 4. Purpose of Holding Purpose: Influencing management control The reporter intends, in connection with the company's business operations, to act in a manner consistent with the company's management objectives should any of the following events under Article 154(1) of the Enforcement Decree of the Financial Investment Services and Capital Markets Act arise: 1. Appointment, dismissal, or suspension of officers 2. Amendment of the articles of incorporation relating to the company's governing bodies (e.g., board of directors) 3. Changes to the company's capital 4. (Deleted) 5. Merger, division, or split-merger of the company 6. Comprehensive share exchange or transfer 7. Transfer or acquisition of all or materially significant parts of the business 8. Disposal of all or materially significant assets 9. Lease of the entire business, management entrustment, contracts for sharing all profits and losses with a third party, or similar contracts — conclusion, modification, or termination 10. Dissolution of the company 5. Reason for Change Method of change: — Reason for change in holdings: — Reason for amendment: Change in collateral pledge ratio attributable to a special related party — PART 2: DETAILS OF LARGE SHAREHOLDING — 1. Breakdown of Holdings by Reporter and Special Related Parties A. Holdings by Type of Securities Relation | Name | DOB/Reg. | Voting shares | Ratio(%) | Other security types (all zero) | Total shares | Total ratio(%) Reporter | Koo Bon-cheon | 640511 | 4,452,789 | 7.67 | — | 4,452,789 | 7.67 Related party | LB Co., Ltd. | 120-87-62897 | 4,826,120 | 8.31 | — | 4,826,120 | 8.31 Related party | Koo Bon-wan | 661030 | 3,189,842 | 5.50 | — | 3,189,842 | 5.50 Related party | Koo Sang-mo | 010317 | 729,480 | 1.26 | — | 729,480 | 1.26 Related party | Koo In-mo | 030830 | 733,656 | 1.26 | — | 733,656 | 1.26 Related party | Lee Seong-eun | 690330 | 817,530 | 1.41 | — | 817,530 | 1.41 Related party | Koo Hye-ran | 601231 | 192,200 | 0.33 | — | 192,200 | 0.33 Related party | Park Seong-eun | 691014 | 0 | — | — | 0 | — Related party | Koo Hye-seon | 620505 | 89,327 | 0.15 | — | 89,327 | 0.15 Related party | Koo Jin-yeong | 940305 | 366,961 | 0.63 | — | 366,961 | 0.63 Related party | Koo Ha-yeong | (960917) | (truncated) | — | — | — | — [Translation truncated]