[Amended] Material event report (merger)

A later amendment corrects this filing, so the terms on this page may be out of date. See the latest version (2026-08-26) →

What happened

Material Event Report (Merger Decision) Huons Co., Ltd. Amendment Report August 4, 2026

1. Disclosure document subject to amendment: Material Event Report (Merger Decision) 2. Date of initial submission of the disclosure document subject to amendment: May 18, 2026 3. Amendment details

Item 10 (Merger schedule), reason: schedule postponed for a parent-company compliance procedure under the duplicate-listing guideline. - Before amendment: Merger contract date 2026-05-18; shareholder record date 2026-07-30; notice period for dissenting shareholders 2026-08-06 to 2026-08-20; expected AGM date 2026-08-21; appraisal-rights exercise period 2026-08-21 to 2026-09-11; creditor objection period 2026-08-21 to 2026-09-22; merger date 2026-09-23; closing report meeting 2026-09-23; expected merger registration date 2026-09-23; expected new-share listing date 2026-10-12. - After amendment: Merger contract date 2026-05-18; shareholder record date 2026-07-30; all other schedule items (notice period for dissenting shareholders, AGM date, appraisal-rights exercise period, creditor objection period, merger date, closing report meeting, merger registration date, new-share listing date) unconfirmed (-).

Item 13 (Appraisal-rights exercise procedure, method, period, place), reason: schedule change. - Before amendment: notice of dissent deadline 3 business days before the AGM (2026-08-18); brokerage firms notify the Korea Securities Depository 2 business days before the AGM (2026-08-19); the Depository notifies the company 1 business day before the AGM (2026-08-20); notice-of-dissent receipt period 2026-08-06 to 2026-08-20; AGM 2026-08-21; appraisal-rights exercise period 2026-08-21 to 2026-09-11. - After amendment: all of the above dates unconfirmed (-).

Item 13 (Expected timing and method of payment for appraisal rights), reason: schedule change. - Before amendment: expected payment date for both Huons and Huons Lab: September 18, 2026. - After amendment: expected payment date for both companies: unconfirmed (-).

Item 17 (Plans for future corporate restructuring): self-initiated correction (no substantive change described).

Item 18 (Other material matters relevant to investment decisions), reason: schedule change. - Added: the closing report meeting under Item 10 is replaced, pursuant to Article 526, Paragraph 3 of the Commercial Act, by a board-resolution public notice procedure; the specific date for that notice is now unconfirmed (-) rather than September 22, 2026 as previously stated.

Material Event Report / Matter Subject to Mandatory Exchange Disclosure To: Financial Services Commission / Korea Exchange May 18, 2026

Company name: Huons Co., Ltd. Representative Director: Song Su-young Head office address: Huons Global Building A, 8th floor, 17 Changeop-ro, Sujeong-gu, Seongnam-si, Gyeonggi-do Phone: 02-854-4700 Website: www.huons.com Preparer: (Title) Chief Disclosure Officer (Name) Kim Jeong-hun (Phone) 02-854-4700

Merger Decision

1. Merger method (a) Huons Co., Ltd. will absorb Huons Lab Co., Ltd. by merger. Surviving company (merging corporation): Huons Co., Ltd. (KOSDAQ-listed). Dissolving company (merged corporation): Huons Lab Co., Ltd. (unlisted). (b) The surviving company's trade name after the merger is Huons Co., Ltd. - Merger form: Not applicable

2. Purpose of the merger To overcome the structural limitation of a shortage of new-drug pipelines to drive future growth and intensifying downward pressure on revenue and profitability from the government's drug-pricing system reform, and to build a full biopharmaceutical value chain and strengthen R&D capability in order to grow into a global pharmaceutical/bio company.

3. Material effects of the merger 1) Effect on management: the surviving company Huons will absorb Huons Lab; Huons will remain listed. Other than the change in shareholding from the merging company's issuance of 3,825,373 new shares (24.20%) to Huons Lab's shareholders as of the merger record date, there is no change in control, including the largest shareholder. 2) Effect on finances: R&D expenses will rise in the short term, but the merger is expected to ultimately improve the Company's financial structure and profitability by strengthening the clinical pipeline and maximizing management efficiency, through integrating the two companies' technical capabilities, utilizing Huons's clinical personnel, know-how and production facilities to reduce duplicate investment and internalize outsourced costs, and R&D synergy. 3) Effect on operations: integrating the two companies' technology, expertise and experience is intended to strengthen the pipeline of synthetic and biologic new-drug development and increase corporate value. In particular, Huons Lab has completed a domestic marketing-authorization application for a finished drug product based on human-derived hyaluronidase, and once its drug-diffusion platform technology is commercialized, synergy from leveraging Huons's infrastructure and sales organization is expected to increase revenue and reduce costs. 4) Effect on shareholder value: the management efficiency and synergy from the merger are expected to increase shareholder value over the long term, as Huons adds Huons Lab's new-drug/biosimilar pipeline to its existing generic-drug-centered business and internalizes superior R&D human resources and original patents, strengthening competitiveness and raising corporate value.

4. Merger ratio: Huons Co., Ltd. : Huons Lab Co., Ltd. = 1 : 0.4256943

5. Basis for calculating the merger ratio 1) Huons common share merger value: calculated, per Article 176-5 of the Enforcement Decree of the Financial Investment Services and Capital Markets Act, as the arithmetic average of the 1-month weighted average closing price, the 1-week weighted average closing price, and the most recent closing price, calculated as of the day before May 18, 2026 (the earlier of the initial board resolution date and the merger agreement date). No premium or discount was applied. (a) 1-month weighted average closing price (A): KRW 32,292 (b) 1-week weighted average closing price (B): KRW 35,095 (c) Most recent closing price (C): KRW 34,800 (d) Arithmetic average (D=(A+B+C)/3): KRW 34,062 (e) Merger value: KRW 34,062 2) Huons Lab common share merger value: as an unlisted company, calculated under Article 176-5 of the Enforcement Decree and Article 5-13 of the Regulation on Issuance and Disclosure of Securities, etc. and its Enforcement Rules, as the weighted average of asset value and income value in a 1:1.5 ratio ("essential value"). Relative value was analyzed for reference only, as fewer than 3 listed companies share Huons Lab's KRX sub-industry classification. (a) Essential value [(A×1+B×1.5)/2.5]: KRW 14,500, Asset value (A): KRW 808; Income value (B): KRW 23,628 (b) Relative value: Not applicable (c) Merger value: KRW 14,500 Resulting merger ratio: Huons common shares to Huons Lab common shares = 1 : 0.4256943. Note: Huons Lab currently has 817,617 outstanding redeemable convertible preferred shares, all of which will be converted into common shares before the merger date; under the contractual refixing terms, the total common shares to be issued on conversion is 905,420 shares. - Corporate value: surviving company KRW 408,051,349,230; dissolving company KRW 129,026,872,500

6. External appraisal - External appraisal conducted: Yes - Basis/reason: required under Article 176-5, Paragraph 7, Item 2(a) of the Enforcement Decree, as a listed company merging with an unlisted company using the merger value method under Item 2(b) of the same provision. - Appraiser: Yichon Accounting Corporation - Appraisal period: April 29, 2026 to May 15, 2026 - Appraisal opinion: Yichon Accounting Corporation reviewed the appropriateness of the merger ratio between Huons (KOSDAQ-listed) and Huons Lab (unlisted), based on Huons's audited separate K-IFRS financial statements and share price data for the fiscal year ended December 31, 2025, Huons Lab's audited K-IFRS financial statements for the same fiscal year, a 16-year business plan from January 2026 to December 2041, and business reports of listed companies in the same KRX sub-industry as Huons Lab. The per-share values underlying the merger ratio were assessed at KRW 34,062 for Huons (par value KRW 500) and KRW 12,671-14,672 for Huons Lab (par value KRW 500), implying a merger-ratio range of 1:0.3719819 to 1:0.4307447. As the agreed ratio of 1:0.4256943 falls within this range, it was assessed as appropriate, and the appraiser found no violation of the merger-value calculation methods prescribed under Article 176-5 of the Enforcement Decree, Article 5-13 of the Regulation on Issuance and Disclosure of Securities, etc. and Articles 4-8 of its Enforcement Rules. The appraisal was performed in compliance with the Financial Supervisory Service's External Appraisal Business Guidelines (2009.6) and the Korean Institute of Certified Public Accountants' Standards for Performing External Appraisal Business under the Capital Markets Act (2024.11), as well as applicable certified-public-accountant ethics requirements.

7. Type and number of new merger shares: Common shares 3,825,373; Preferred shares -

8. Merger counterparty - Company name: Huons Lab Co., Ltd. - Main business: Biopharmaceutical R&D - Relationship with the Company: Affiliate - Financial details for the most recent fiscal year (KRW): Total assets 8,261,890,851; Paid-in capital 4,040,394,000; Total liabilities 10,062,942,137; Revenue 83,816,403; Total equity -1,801,051,286; Net income -10,189,367,413 - External audit: auditor Samil PricewaterhouseCoopers; opinion: unqualified

9. Newly formed company from the merger: Not applicable (all items -)

10. Merger schedule: see the amendment details above; the previously announced dates for the notice-of-dissent period, AGM, appraisal-rights exercise period, creditor objection period, merger date, merger registration date and new-share listing date are now unconfirmed. Merger contract date: May 18, 2026. Shareholder record date: July 30, 2026.

11. Whether this is a backdoor listing: Not applicable

12. Whether another entity's backdoor-listing requirements are met: Not applicable

13. Appraisal rights - Requirements: under Article 522-3 of the Commercial Act and Article 165-5 of the Financial Investment Services and Capital Markets Act, a shareholder of record as of the record date who notifies the company in writing of its dissent to the board's merger resolution before the AGM may demand that the company purchase its shares, in writing stating the type and number of shares, within 20 days of the AGM resolution date; appraisal rights are limited to shares acquired before the board resolution was disclosed (or, if acquired by the next business day after disclosure, upon proof of a purchase contract, termination of a securities lending agreement, or other qualifying act) and continuously held through the exercise date; shares sold and reacquired during this period lose appraisal rights, and the right cannot be withdrawn once exercised; a shareholder who voted for the merger at the AGM after giving written notice of dissent cannot exercise appraisal rights. As Huons is KOSDAQ-listed, under Article 165-5, Paragraph 2 of the Financial Investment Services and Capital Markets Act, it must purchase the shares within one month of the end of the appraisal-rights exercise period. - Expected purchase price: KRW 32,886 - Exercise procedure, method, period and place: a dissenting shareholder of record (or, for beneficial shareholders holding shares through a securities firm, the shareholder notifies that securities firm) must give written notice of dissent to the merger resolution before the AGM; the securities firm must in turn notify the Korea Securities Depository, which notifies the company on the shareholder's behalf, each step subject to deadlines before the AGM that are currently unconfirmed pending the revised schedule. Appraisal-rights demands are filed with Huons (surviving company) at Huons Global Building A, 8th floor, Changeop-ro 17, Sujeong-gu, Seongnam-si, Gyeonggi-do (for shareholders of record) or through the relevant securities firm (for beneficial shareholders); the same applies to Huons Lab (dissolving company) at Huons Global Building A, 7th floor, same address. The notice-of-dissent period, AGM date and appraisal-rights exercise period previously announced (notice-of-dissent period 2026-08-06 to 2026-08-20; AGM 2026-08-21; exercise period 2026-08-21 to 2026-09-11) are now unconfirmed and subject to change. - Expected timing and method of payment: for shareholders of record, by transfer to the bank account the shareholder has registered; for beneficial shareholders holding shares through a securities firm, by transfer to the shareholder's account at that securities firm. The expected payment dates previously announced (September 18, 2026 for both Huons and Huons Lab) are now unconfirmed and may change depending on the companies' circumstances. - Restrictions on appraisal rights: a shareholder who sells and reacquires shares within the relevant period loses appraisal rights, and the right cannot be withdrawn once exercised; a shareholder who voted for the merger after giving written notice of dissent cannot exercise appraisal rights. - Effect on the contract: after each company's AGM approves the merger, if the aggregate purchase amount of shares for which appraisal rights are exercised exceeds KRW 30 billion for Huons or KRW 4 billion for Huons Lab (measured as of the end of the appraisal-rights exercise period), the merging parties may decide by board resolution whether to proceed with the merger.

14. Date of board resolution (decision date): May 18, 2026 - Independent (outside) director* attendance: Present (persons) 3; Absent (persons) 0

15. Whether a put-option or similar agreement was concluded: No

16. Whether subject to filing of a securities registration statement: Yes

17. Plans for future corporate restructuring: no specific restructuring plans have been decided following completion of the merger; any future resolutions will be disclosed under the applicable disclosure rules.

18. Other material matters relevant to investment decisions (a) Under Articles 522 and 434 of the Commercial Act, approval of the merger at the general meeting of shareholders is a special resolution matter, requiring at least two-thirds of the voting rights of shareholders present and at least one-third of total shares issued; if this threshold is not met, the merger may fail. (b) Other than cash paid in lieu of fractional shares arising from the new-share allotment, no payment of any kind will be made to shareholders of the companies participating in the merger. (c) Item 7 (type and number of new merger shares) may change depending on the results of Huons Lab shareholders' exercise of appraisal rights and the treatment of fractional shares. (d) The financial details of Huons Lab under Item 8 are based on its financial statements as of the end of fiscal year 2025. (e) The matters and schedule under Item 10 may change through consultation with relevant authorities, approvals, and discussions between the contracting parties. (f) The closing report meeting under Item 10 is replaced, pursuant to Article 526, Paragraph 3 of the Commercial Act, by a board-resolution public notice procedure. (g) Details on the "expected purchase price" in Item 13 are as follows. Article 165-5, Paragraph 3 of the Financial Investment Services and Capital Markets Act provides that the purchase price is to be determined by agreement between the shareholder and the company; if no agreement is reached, the price is calculated under Article 176-7, Paragraph 3 of the Enforcement Decree based on the trading price of the shares on the exchange before the board resolution date; a dissenting shareholder may petition the court to determine the purchase price.

[Huons Expected Appraisal-Rights Purchase Price Calculation] (under Article 176-7, Paragraph 3 of the Enforcement Decree) - Company's proposed price for negotiation: KRW 32,886 - Basis: the amount calculated under the purchase-price method of Article 165-5 of the Financial Investment Services and Capital Markets Act and Article 176-7 of its Enforcement Decree - Treatment if agreement is not reached: the amount calculated under the same provisions based on the exchange trading price of the shares before the board resolution date; a dissenting shareholder may petition the court to determine the purchase price.

(1) Method of calculating the expected purchase price (base date: May 15, 2026) - ① 2-month weighted average price: KRW 31,271 (2026-03-16 to 2026-05-15) - ② 1-month weighted average price: KRW 32,292 (2026-04-16 to 2026-05-15) - ③ 1-week weighted average price: KRW 35,095 (2026-05-11 to 2026-05-15) - Base purchase price [①+②+③)/3]: KRW 32,886

(2) Calculation detail (Unit: KRW, shares), date, closing price, trading volume, closing price × trading volume: 2026/05/15: 34,800; 108,454; 3,774,199,200 2026/05/14: 34,850; 91,761; 3,197,870,850 2026/05/13: 36,050; 265,024; 9,554,115,200 2026/05/12: 35,250; 336,137; 11,848,829,250 2026/05/11: 34,250; 296,555; 10,157,008,750 2026/05/08: 30,250; 130,449; 3,946,082,250 2026/05/07: 28,850; 144,021; 4,155,005,850 2026/05/06: 27,450; 56,853; 1,560,614,850 2026/05/04: 26,450; 72,635; 1,921,195,750 2026/04/30: 26,400; 20,942; 552,868,800 2026/04/29: 26,700; 25,527; 681,570,900 2026/04/28: 26,700; 23,555; 628,918,500 2026/04/27: 26,800; 38,759; 1,038,741,200 2026/04/24: 26,850; 31,638; 849,480,300 2026/04/23: 26,600; 36,231; 963,744,600 2026/04/22: 26,700; 7,617; 203,373,900 2026/04/21: 26,500; 30,353; 804,354,500 2026/04/20: 27,000; 14,131; 381,537,000 2026/04/17: 27,350; 48,362; 1,322,700,700 2026/04/16: 27,300; 18,928; 516,734,400 2026/04/15: 26,800; 20,675; 554,090,000 2026/04/14: 26,300; 12,980; 341,374,000 2026/04/13: 26,050; 18,916; 492,761,800 2026/04/10: 25,850; 16,933; 437,718,050 2026/04/09: 25,350; 8,384; 212,534,400 2026/04/08: 25,250; 16,337; 412,509,250 2026/04/07: 24,750; 18,104; 448,074,000 2026/04/06: 25,000; 9,150; 228,750,000 2026/04/03: 25,300; 6,372; 161,211,600 2026/04/02: 25,450; 29,837; 759,351,650 2026/04/01: 26,300; 9,542; 250,954,600 2026/03/31: 25,350; 15,431; 391,175,850 2026/03/30: 25,750; 13,136; 338,252,000 2026/03/27: 26,250; 12,448; 326,760,000 2026/03/26: 26,250; 19,371; 508,488,750 2026/03/25: 26,400; 20,487; 540,856,800 2026/03/24: 25,950; 14,833; 384,916,350 2026/03/23: 25,450; 15,526; 395,136,700 2026/03/20: 26,300; 15,507; 407,834,100 2026/03/19: 25,900; 13,057; 338,176,300 2026/03/18: 26,350; 11,119; 292,985,650 2026/03/17: 26,300; 10,254; 269,680,200 2026/03/16: 26,150; 11,541; 301,797,150 - 2-month weighted average price: KRW 31,271; 1-month weighted average price: KRW 32,292; 1-week weighted average price: KRW 35,095; base purchase price: KRW 32,886 - Source: Korea Exchange Market Data System (http://data.krx.co.kr)

Huons Lab is unlisted, so its expected appraisal-rights purchase price is its merger value of KRW 14,500.

(h) If the AGM rejects the merger, appraisal rights lapse and the merger agreement does not take effect. (i) A shareholder who has demanded appraisal rights cannot withdraw that demand after the end of the appraisal-rights exercise period. (j) This merger requires a business-combination filing, to be made promptly after the merger is completed; as a merger between affiliates, it qualifies for simplified review under the business-combination review standards. (k) Termination conditions in the merger agreement include: Article 13 (Conditions Precedent), each party's obligation to complete the merger is conditioned on, among other things, due approval of the agreement and merger by each party's board and/or shareholders, completion of required procedures and government/third-party approvals, the accuracy of each party's representations and warranties, performance of covenants, absence of material adverse change, absence of any prohibiting law or order, and conversion of all of Huons Lab's redeemable convertible preferred shares into common shares by the merger date; and Article 14 (Termination), the parties may terminate by written agreement at any time before the merger date, or either party may terminate immediately on written notice if, among other things, a material adverse change occurs, a required government approval is denied or conditioned in a way materially harmful to either party, a condition precedent becomes incapable of being satisfied, a party's representations prove materially inaccurate, a party breaches a covenant and fails to cure within 10 business days of notice, or the aggregate appraisal-rights purchase amount exceeds the KRW 30 billion (Huons) / KRW 4 billion (Huons Lab) thresholds described above and the relevant board resolves to halt the merger; upon termination (absent other agreement) neither party retains further rights or obligations under the agreement, without prejudice to damages claims for breach, and certain surviving provisions (including Articles 14, 16 and 17) remain in effect. (l) Because appraisal rights under this merger would not be allotted new merger shares for treasury shares Huons Lab comes to hold through its shareholders' exercise of appraisal rights, the number of new merger shares to be issued stated above may change by the time the merger is finalized. (m) To fulfill directors' duty of loyalty under Article 382-3 of the Commercial Act and to implement the fairness-enhancing measures recommended by the Ministry of Justice's "Guidelines on Directors' Conduct in Corporate Reorganizations," the merging companies (i) operated a special committee composed of outside directors and (ii) obtained review by an independent external expert (a law firm) to secure the fairness and procedural adequacy of the merger. Huons's special committee consisted of 2 outside directors and 1 independent external expert (an attorney), and met twice before the board resolution on the merger to review the merger structure, terms, the basis for the merger ratio, and procedural adequacy in depth; after hearing detailed explanations from, and posing questions to, the independent accounting firm and law firm, and requesting additional explanation and supplementary materials on the method and key assumptions for calculating the merger ratio, the potential for post-merger improvement in financial structure, and minority-shareholder protection measures, the special committee concluded that the merger serves the interests of the Company and all shareholders and poses no risk of harming overall shareholder interests or treating minority shareholders unfairly or discriminatorily. After comprehensively considering the special committee's and the external experts' review, the board approved the merger agreement, finding the purpose and expected effects reasonable, the transaction terms fair, and the agreement consistent with applicable law. For details of Huons's decision-making process, please refer to the board minutes and board opinion attached to this material event report. ※ For further details of this merger, please refer to the Company's securities registration statement to be disclosed later. ※ This disclosure supersedes the Company's response of May 13, 2026 to an inquiry regarding market rumors or reports (unconfirmed). ※ This amendment to the material event report is due to a schedule change, but as of the amendment date (2026.08.04) the revised schedule has not yet been finalized; once it is finalized, the Company will re-disclose it through a board resolution and a further amendment to this material event report. (condensed translation)