1032-00003 · Client 1032 · Correspondence

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PRIVILEGED AND CONFIDENTIAL — ATTORNEY WORK PRODUCT

CALDERWOOD & HARKNESS LLP One Liberty Plaza, 42nd Floor New York, New York 10006

Telephone: (212) 558-4000 Facsimile: (212) 558-3588 www.calderwoodharkness.com

January 27, 2026

VIA EMAIL AND OVERNIGHT COURIER

Martin Ashford, Esq. Partner, Capital Markets Varen & Kessler LLP 51 West 52nd Street New York, New York 10019

cc: Priya Ranganathan, Senior Associate, Varen & Kessler LLP (via email: pranganathan@varenkessler.com)

Re: Halcyon Semiconductor Aktiengesellschaft — US Initial Public Offering of American Depositary Shares; Due Diligence Protocol and Section 11/12 Defense Memorandum Framework

C&H Matter No. 1032-00003

Dear Martin:

I. Introduction and Purpose

As you know, this firm serves as US securities counsel to Halcyon Semiconductor Aktiengesellschaft ("Halcyon" or the "Company"), a German Aktiengesellschaft (Aktiengesellschaft nach deutschem Recht) with its registered office in Munich, Germany (registered in the Commercial Register (Handelsregister) of the Local Court (Amtsgericht) of Munich under registration number HRB 217458), in connection with the proposed US initial public offering (the "Offering") of American Depositary Shares ("ADSs"), each representing two ordinary shares (Stammaktien) of the Company, through a Level III American Depositary Receipt program sponsored by the Company.

We understand that your firm, Varen & Kessler LLP ("V&K"), serves as US counsel to the underwriting syndicate in connection with the Offering. The underwriting syndicate is led by Westbridge Securities LLC, acting as lead left bookrunner and representative of the several underwriters (the "Representative"), together with Pinnacle Morgan & Co., Inc. and Andover Barcliffe Group Inc., each acting as joint bookrunners, and Northpointe Capital LLC, acting as co-manager (collectively, the "Underwriters").

The purpose of this letter is twofold. First, we write to establish a mutually agreed due diligence protocol (the "Protocol") that will govern the joint and independent due diligence activities to be undertaken by both Calderwood & Harkness LLP ("C&H") and V&K in connection with the Offering. Second, we seek to outline the framework for the due diligence defense memorandum (the "Due Diligence Defense Memorandum" or "Defense Memorandum") to be prepared jointly by our respective firms in connection with potential liability under Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended (the "Securities Act").

As discussed at the organizational meeting held on January 22, 2026, at which representatives of C&H, V&K, the Company, the Underwriters, and the respective German counsel for the issuer and the underwriters participated, the parties agreed on the general framework and indicative timeline for the due diligence investigation. We confirmed at that meeting that due diligence would formally commence on January 27, 2026 — the date of this letter — and that access to the Company's virtual data room would be provided to all counsel and relevant advisors on or about this date.

The Company intends to file a Registration Statement on Form F-1 (the "Registration Statement") under the Securities Act in connection with the Offering, with a targeted confidential submission to the US Securities and Exchange Commission (the "SEC") on or about April 14, 2026, pursuant to the accommodations available to emerging growth companies and foreign private issuers. A thorough and well-documented due diligence record must be established well in advance of such confidential submission, and must thereafter be maintained and updated through the effectiveness of the Registration Statement, pricing, and closing of the Offering.

As discussed at the organizational meeting, the Offering targets aggregate gross proceeds of approximately $900,000,000. The Offering will consist of (a) a primary offering of 15,000,000 ADSs, representing 30,000,000 newly issued ordinary shares of the Company, and (b) a secondary offering of 6,400,000 ADSs, representing 12,800,000 existing ordinary shares to be sold by the selling shareholders, namely Rheintal Industrieholding GmbH (selling 4,250,000 ADSs representing 8,500,000 existing shares) and Kestrel Capital Partners AG (selling 2,150,000 ADSs representing 4,300,000 existing shares). Each ADS will represent two ordinary shares (the "ADS Ratio"), with a proposed price range of $39.00 to $45.00 per ADS. The Company intends to apply for listing of the ADSs on the Nasdaq Global Select Market under the ticker symbol "HCYN."

We set forth below the detailed provisions of the Protocol and the Defense Memorandum framework for your review and confirmation.

II. Scope of Due Diligence

A. General Principles

The due diligence investigation contemplated by this Protocol is intended to serve several critical purposes. Foremost among them, the investigation must provide a reasonable basis for the Underwriters to establish a defense under Section 11(b)(3) of the Securities Act (commonly referred to as the "due diligence defense") in the event of any claim brought under Section 11 of the Securities Act with respect to alleged material misstatements or omissions in the Registration Statement. Equally important, the investigation must be sufficiently thorough and well-documented to permit both issuer's counsel (C&H) and underwriters' counsel (V&K) to deliver their respective negative assurance letters (commonly referred to as "10b-5 letters" or "10b-5 disclosure letters") at closing, which is currently targeted for July 6, 2026.

As both firms are aware, Halcyon qualifies as a "foreign private issuer" as defined in Rule 3b-4 under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and the due diligence investigation must accordingly address both US securities law requirements and the cross-border aspects inherent in a transaction involving a German Aktiengesellschaft. The Company maintains a complex organizational structure with subsidiaries and operations in multiple jurisdictions, including Germany (where the parent entity and its principal fabrication and R&D operations are domiciled), the United States (through its wholly owned subsidiary Halcyon Semiconductor USA Inc., a Delaware corporation with operations in California), Singapore (through Halcyon Asia Pacific Pte. Ltd.), the People's Republic of China (through Halcyon Shanghai Semiconductor Co., Ltd.), and the Czech Republic (through Halcyon Automotive Components s.r.o., based in Brno). Each of these jurisdictions presents unique legal, regulatory, and operational considerations that must be addressed in the course of the due diligence investigation.

To facilitate efficient and comprehensive document review, the Company has established a virtual data room (the "Data Room") hosted on the Thackeray Solutions platform. All documents uploaded by the Company and its advisors will be indexed and tracked via the master due diligence request list (the "Request List") previously circulated by C&H to the Company, Bähr Stein Rechtsanwälte PartGmbB ("Bähr Stein," German counsel to the Company), and the respective working groups. Both C&H and V&K, together with their respective associates and other authorized personnel, shall have full access to the Data Room throughout the due diligence period, subject to the confidentiality and privilege protections described in Section VII below.

B. Document Review

Both C&H and V&K shall conduct a comprehensive review of all documents that are responsive to the Request List previously circulated by C&H to the Company and Bähr Stein (Dr. Christoph Maurelban and Johanna Weiß). The documents requested and to be reviewed are organized into the following principal categories:

1. Corporate and Organizational Documents. This category encompasses the foundational corporate documents of Halcyon and each of its material subsidiaries. For the parent entity, the review will include the Company's Satzung (articles of association) in their current form as adopted by the most recent shareholders' meeting, extracts from the Commercial Register (Handelsregisterauszug) of the Amtsgericht München, the Company's current shareholder register (Aktienregister), and complete minute books of the Vorstand (Management Board) and Aufsichtsrat (Supervisory Board) for the three fiscal years ended December 31, 2023, 2024, and 2025, together with any minutes from the current fiscal year through the date of closing. For each material subsidiary, the review will include all organizational and governing documents, including: (a) the certificate of incorporation, bylaws, and minutes of the board of directors and stockholders of Halcyon Semiconductor USA Inc. (incorporated in the State of Delaware); (b) the Gesellschaftsvertrag and related organizational documents of Halcyon Power Solutions GmbH (registered in Dresden, Germany); (c) the memorandum and articles of association of Halcyon Asia Pacific Pte. Ltd. (incorporated in Singapore); (d) the articles of association and business license of Halcyon Shanghai Semiconductor Co., Ltd. (established under the laws of the People's Republic of China with its registered office in Shanghai); and (e) the organizational documents of Halcyon Automotive Components s.r.o. (registered in Brno, Czech Republic). We will also review all intercompany agreements, capital contribution records, and organizational charts.

2. Material Contracts. We will conduct a thorough review of all material contracts to which the Company or any of its subsidiaries is a party, including without limitation: supply agreements with key raw materials and equipment suppliers (including silicon carbide wafer suppliers and epitaxial growth equipment vendors); customer contracts, particularly long-term supply arrangements with automotive and industrial OEM customers; joint development agreements and strategic collaboration arrangements; technology license agreements (both inbound and outbound); the Company's existing revolving credit facility (noting that the Company has disclosed that approximately $100,000,000 of the net proceeds from the primary offering will be allocated to the partial repayment of outstanding borrowings under this facility); and any agreements containing change-of-control provisions, anti-assignment clauses, or other restrictions that may be triggered by the Offering or the resultant change in the Company's shareholder composition.

3. Intellectual Property. Given that Halcyon's competitive position in the power semiconductor market is critically dependent on its technology portfolio, the IP review constitutes one of the most important components of the due diligence process. This review will encompass the Company's entire patent portfolio relating to silicon carbide (SiC) and gallium nitride (GaN) power semiconductor technologies, including all issued patents, pending patent applications, and continuations in each relevant jurisdiction. The review will also cover trade secret protections and policies, trademark registrations and applications, domain names, IP licensing agreements (both as licensor and licensee), and any pending or threatened intellectual property litigation or disputes. We will examine the Company's freedom-to-operate analyses and any third-party opinions of counsel regarding non-infringement or invalidity.

4. Litigation and Regulatory Proceedings. This category includes all pending and threatened litigation involving the Company or any subsidiary, all pending or concluded arbitration proceedings, and all governmental or regulatory investigations, inquiries, or enforcement actions. We will request detailed descriptions of each matter, together with copies of complaints, answers, counterclaims, significant motion papers, and settlement agreements. We will also review the Company's litigation reserves and assess the adequacy of the Company's disclosure of litigation-related contingencies.

5. Environmental and Manufacturing Compliance. Given the nature of semiconductor fabrication, which involves the use of hazardous chemicals and materials, environmental compliance is a critical area of due diligence. We will review all environmental permits, licenses, and authorizations held by the Company and its subsidiaries for each manufacturing facility, including: the Company's headquarters and principal fabrication facility in Munich; the Dresden Fab 2 facility (operated by Halcyon Power Solutions GmbH); the Dresden Fab 3 facility, which is currently under construction and represents a major component of the Company's use of proceeds; and the assembly and test facility in Brno, Czech Republic (operated by Halcyon Automotive Components s.r.o.). The review will also encompass hazardous materials handling protocols, waste disposal practices, environmental impact assessments, and any past or present environmental remediation obligations.

6. Employee Benefit Plans and Compensation. We will review all material employee benefit plans and compensation arrangements maintained by the Company and its subsidiaries, including both German and non-German plans. Of particular significance, we will review the documentation relating to the Halcyon Employee Stock Ownership Trust (the "ESOT"), which currently holds approximately 3.1% of the Company's outstanding share capital (approximately 6,665,000 ordinary shares), including the trust deed, allocation policies, and the impact of the Offering on the ESOT's holdings. We will also review executive compensation arrangements for each member of the Vorstand, including Dr. Friedrich Wendt (Chief Executive Officer / Vorstandsvorsitzender), Katarina Dalmqvist (Chief Financial Officer / Finanzvorstand), Dr. Marcus Helder (Chief Technology Officer), Ingrid Baumann (Chief Operating Officer), and Wilhelm Ostermann (General Counsel / Chefjustitiar), as well as compensation arrangements for members of the Aufsichtsrat.

7. Related-Party Transactions. We will conduct a thorough review of all transactions between the Company and its related parties, with particular focus on transactions with Rheintal Industrieholding GmbH ("Rheintal"), the Wendt family holding company that currently holds approximately 22.3% of the Company's outstanding share capital and is expected to hold approximately 16.1% following the Offering. Rheintal is controlled by Margarethe Wendt, who is the sister of the Company's Chief Executive Officer, Dr. Friedrich Wendt. This familial relationship and the significant shareholding of Rheintal necessitate a heightened level of scrutiny of all transactions between the Company and Rheintal, as well as careful consideration of disclosure obligations under Item 7.B of Form 20-F (as incorporated by reference into Form F-1). We will also review relationships and transactions involving members of the Supervisory Board.

8. Sanctions, Anti-Corruption, and Export Controls. Given the Company's global operations, and in particular its subsidiary in Shanghai, China, this area of due diligence is of heightened importance. The review will encompass the Company's compliance with US sanctions administered by the Office of Foreign Assets Control ("OFAC"), EU sanctions regulations, the US Foreign Corrupt Practices Act ("FCPA"), the UK Bribery Act 2010, and applicable export control regulations, including the US Export Administration Regulations ("EAR"), the International Traffic in Arms Regulations ("ITAR"), and EU dual-use export control regulations. We will give particular attention to Halcyon Shanghai Semiconductor Co., Ltd.'s operations, customer base, and compliance with applicable restrictions on the export and re-export of semiconductor technology and products.

9. Financial and Tax Records. This category includes all audited consolidated financial statements of the Company prepared in accordance with International Financial Reporting Standards as issued by the International Accounting Standards Board ("IFRS") for the fiscal years ended December 31, 2023 and December 31, 2024, together with the unaudited consolidated financial statements for the fiscal year ended December 31, 2025. The Company has informed us that its unaudited financial results for FY2025 reflect revenue of approximately €3,820 million, EBITDA of approximately €1,069 million (representing an EBITDA margin of approximately 28.0%), and net income of approximately €612 million. We will also review management accounts, budgets, projections, and related financial planning materials, as well as tax returns filed in each relevant jurisdiction, transfer pricing documentation, and materials relevant to the Passive Foreign Investment Company ("PFIC") analysis that will be included in the prospectus.

10. Insurance Program. We will review the Company's comprehensive insurance program, with particular emphasis on the adequacy of the Company's directors' and officers' liability insurance ("D&O Insurance") in light of the Offering. We understand that the Company's current D&O insurance program provides total limits of $75,000,000, structured across four layers as follows: (i) Thornhill Assurance plc as primary insurer, providing a limit of $15,000,000; (ii) Arcadian Indemnity Corp. as first excess insurer, providing $20,000,000 in excess of $15,000,000; (iii) Helmsman Re Ltd. as second excess insurer, providing $20,000,000 in excess of $35,000,000; and (iv) Nordic Specialty Insurance SE as third excess insurer, providing $20,000,000 in excess of $55,000,000. We will also review the Company's property insurance, product liability insurance, and general commercial liability insurance policies.

Both C&H and V&K shall independently review documents in the Data Room. C&H will prepare and share due diligence memoranda on each of the above categories as the document review progresses, identifying key findings, areas of concern, and disclosure implications. V&K will conduct its own independent review of the Data Room documents and will supplement C&H's memoranda as needed from the perspective of the Underwriters' due diligence defense.

With respect to documents governed by German law or requiring analysis under German corporate or regulatory law, the document review will be coordinated with Bähr Stein Rechtsanwälte PartGmbB (issuer's German counsel; Dr. Christoph Maurelban, Partner, and Johanna Weiß, Senior Associate) and Prumvane Thornton LLP (underwriters' German counsel; Dr. Stefan Braun, Partner, Frankfurt office at Neue Mainzer Straße 52, 60311 Frankfurt am Main). Each German counsel will prepare German-law due diligence reports on matters within their respective scope and will coordinate with their US counterparts to ensure that all cross-border issues are addressed comprehensively.

C. Financial Due Diligence

Financial due diligence will be conducted in close coordination with the Company's independent auditors, Blackmere & Whitfield LLP (the "Auditors"). The Company's audit is led by Graham Templeton, Partner, based in the Blackmere & Whitfield New York office at 7 Times Square, New York, New York 10036, with Dieter Kaufmann serving as Lead Engagement Partner in the Blackmere & Whitfield GmbH Wirtschaftsprüfungsgesellschaft Munich office at Ganghoferstraße 29, 80339 Munich, Germany.

Both C&H and V&K will participate in auditor due diligence sessions (commonly referred to as "accountants' sessions") to be scheduled with the Auditors at appropriate intervals throughout the due diligence process. The topics to be addressed at these sessions will include, without limitation:

(a) the scope and procedures of the audit of the Company's IFRS consolidated financial statements for FY2023 and FY2024, including any changes in the scope of the audit from prior years;

(b) significant accounting policies and estimates applied by the Company, including those involving management judgment, and any changes in accounting policies or estimates during the relevant periods;

(c) revenue recognition practices, including the recognition of revenue from long-term supply contracts, licensing arrangements, and development agreements;

(d) material audit adjustments, proposed adjustments that were not recorded, and significant findings or recommendations communicated to the Company's management or Audit Committee;

(e) the procedures to be followed in connection with the comfort letter to be delivered by the Auditors to the Underwriters at pricing and closing, in accordance with the professional standards set forth in Statement on Auditing Standards No. 72 ("SAS 72") and, to the extent applicable, International Standard on Assurance Engagements 3000 ("ISAE 3000");

(f) the PCAOB registration status of Blackmere & Whitfield GmbH Wirtschaftsprüfungsgesellschaft and any limitations on the PCAOB's ability to inspect the auditor's workpapers; and

(g) the auditor's assessment of the Company's internal control over financial reporting, recognizing that the Company's first obligation to include a management assessment of internal controls under Section 404(a) of the Sarbanes-Oxley Act of 2002 will apply for the fiscal year ending December 31, 2026, and the first obligation to include an attestation report of the independent auditor under Section 404(b) will apply for the fiscal year ending December 31, 2027.

The key financial data points to be verified through the financial due diligence process include the following:

We propose the following schedule for accountants' sessions: (i) an initial accountants' session during the week of February 10–12, 2026, within approximately two weeks of the commencement of due diligence; (ii) a follow-up session to be held prior to the circulation of the first draft of the Form F-1, which is targeted for March 9, 2026; and (iii) a bring-down session to be held prior to closing to confirm the continued accuracy of the financial information in the Registration Statement and to address any developments since the prior session.

III. Management Interviews

A. Interview Schedule and Format

Management interviews (which, in subsequent rounds, are commonly referred to as "bring-down" interviews) constitute a core component of the due diligence process and will be conducted jointly by C&H and V&K. The participation of both issuer's counsel and underwriters' counsel in these sessions is critical to establishing a comprehensive due diligence record and to ensuring that all material information elicited during the interviews is available to both firms for purposes of prospectus drafting and the Defense Memorandum.

We propose the following schedule of management interview rounds:

(a) Initial Interview Round: To be completed during the period of February 3–14, 2026. This initial round is intended to elicit the foundational information necessary to inform the preparation of the first draft of the Form F-1, with a target circulation date of March 9, 2026.

(b) Pre-Filing Update Interview: To be conducted during the period of April 7–9, 2026, prior to the confidential submission of the Registration Statement to the SEC, currently targeted for April 14, 2026. The purpose of this session is to confirm the continued accuracy of the information previously provided by management and to identify any material developments since the initial interview round.

(c) Pre-Pricing Update Interview: To be conducted during the period of June 16–18, 2026, prior to the launch of the roadshow (targeted for June 23, 2026) and pricing (targeted for July 1, 2026). This session will address any developments arising during the SEC review process and will confirm the accuracy of the disclosure in the final prospectus.

(d) Closing Bring-Down Interview: To be conducted on or about July 3, 2026, prior to closing on July 6, 2026. This final interview will serve as the closing bring-down and will confirm that no material adverse changes have occurred since pricing and that all disclosure remains accurate and complete.

All interviews may be conducted by video conference or in person at the Company's headquarters at Maximilianstraße 72, 80539 Munich, Germany, or at C&H's offices in New York, as may be mutually agreed upon for each session. The Company's German counsel (Bähr Stein) and the Underwriters' German counsel (Prumvane Thornton) will participate simultaneously in sessions involving matters of German corporate governance, Aktiengesetz requirements, and Supervisory Board matters, as appropriate.

B. Proposed Interviewees and Topics

We propose the following interviews with members of the Company's management, Supervisory Board, and selling shareholder representatives, organized by interviewee and the principal topics to be addressed:

1. Dr. Friedrich Wendt, Chief Executive Officer (*Vorstandsvorsitzender*). Dr. Wendt will be interviewed regarding the Company's overall corporate strategy and vision; the competitive landscape in the global power semiconductor market, with particular focus on silicon carbide (SiC) and gallium nitride (GaN) technologies and the Company's competitive positioning relative to other market participants; key customer and supplier relationships and the concentration, duration, and terms of such relationships; the Company's expansion plans, including the construction and anticipated commissioning of the Dresden Fab 3 facility; the industry outlook across the Company's principal end markets, including automotive (electric vehicle power electronics), industrial automation, and renewable energy applications; and the nature, terms, and history of related-party transactions between the Company and Rheintal Industrieholding GmbH, including any ongoing commercial arrangements and the rationale for the selling shareholder transaction.

2. Katarina Dalmqvist, Chief Financial Officer (*Finanzvorstand*). Ms. Dalmqvist will be interviewed regarding the Company's financial performance and trends, including the revenue compound annual growth rate of approximately 9.0% achieved between FY2023 and FY2025; the proposed use of proceeds from the Offering, specifically the allocation of approximately $280,000,000 to the Fab 3 expansion, approximately $140,000,000 to GaN research and development initiatives, approximately $100,000,000 to the partial repayment of the Company's revolving credit facility, and the balance of approximately $87,950,000 (based on an assumed initial public offering price of $42.00 per ADS, which is the midpoint of the proposed range) to general corporate purposes and working capital; the Company's capital structure, including outstanding indebtedness and equity; foreign exchange exposure, with particular attention to the EUR/USD exchange rate (noted at 1.078 as of January 10, 2026) and the Company's hedging practices; material accounting judgments and estimates; and the Company's preparations for compliance with the internal control reporting requirements of Section 404 of the Sarbanes-Oxley Act (with Section 404(b) attestation first required for the fiscal year ending December 31, 2027).

3. Dr. Marcus Helder, Chief Technology Officer. Dr. Helder will be interviewed regarding the Company's technology and product roadmap; the composition and strategic significance of the Company's intellectual property portfolio, including its patent strategy for SiC and GaN technologies; the Company's research and development pipeline and prioritization of R&D investments; competitive technology risks and the pace of technological change in the power semiconductor industry; and export control implications arising from the Company's technology, including the classification of the Company's products and technical data under applicable US and EU export control regulations.

4. Ingrid Baumann, Chief Operating Officer. Ms. Baumann will be interviewed regarding the Company's manufacturing operations across all facilities, including the Munich headquarters and fabrication facility, the Dresden Fab 2 production facility, the Dresden Fab 3 facility currently under construction, and the Brno assembly and test facility; supply chain management practices, including raw material sourcing and supplier diversification; capacity utilization and planning; environmental, health, and safety compliance at each manufacturing facility; and the Company's global workforce, which currently comprises approximately 8,400 employees worldwide.

5. Wilhelm Ostermann, General Counsel (*Chefjustitiar*). Mr. Ostermann will be interviewed regarding all pending and threatened litigation and regulatory proceedings involving the Company or its subsidiaries; the Company's corporate governance structure, including the functioning of the two-tier board system (Vorstand and Aufsichtsrat) under German law and the Aktiengesetz; the terms and significance of the Company's material contracts; the Company's compliance programs, including those addressing anti-corruption, sanctions, and export controls; the Company's insurance program and the adequacy of coverage in light of the Offering; and regulatory approvals required in connection with the Offering, including any requirements under German or other applicable law.

6. Prof. Dr. Anneliese Voss, Chair of the Supervisory Board (*Aufsichtsratsvorsitzende*). Prof. Dr. Voss will be interviewed regarding the Supervisory Board's oversight of the Company's management and operations; the independence of the members of the Supervisory Board; the Company's governance practices and policies; the composition and responsibilities of the Supervisory Board's committees, including the audit committee; and the Supervisory Board's approval of the issuance of new shares in connection with the Offering and the exclusion of preemptive rights (Bezugsrechtsausschluss) under the Aktiengesetz.

7. Selling Shareholder Representatives. We propose interviews with the following representatives of the selling shareholders:

(a) Margarethe Wendt, Managing Director, Rheintal Industrieholding GmbH. Ms. Wendt will be interviewed regarding the ownership structure of Rheintal; the motivation for Rheintal's partial divestiture in the Offering (8,500,000 ordinary shares, equivalent to 4,250,000 ADSs); Rheintal's post-Offering intentions, including its anticipated retained holding of approximately 39,445,000 ordinary shares (representing approximately 16.1% of the Company's outstanding share capital on a post-Offering basis); and the nature of Ms. Wendt's family relationship with the Company's Chief Executive Officer, Dr. Friedrich Wendt (who is her brother), and any implications for governance and related-party matters.

(b) Henrik Sørensen, Managing Partner, Kestrel Capital Partners AG. Mr. Sørensen will be interviewed regarding Kestrel Capital Partners' original investment thesis for its investment in Halcyon; the motivation for Kestrel's partial divestiture in the Offering (4,300,000 ordinary shares, equivalent to 2,150,000 ADSs); and Kestrel's post-Offering plans, including its anticipated retained holding of approximately 16,555,000 ordinary shares (representing approximately 6.8% of the Company's outstanding share capital on a post-Offering basis).

C. Interview Procedures

To ensure the efficiency and completeness of the interview process, C&H and V&K will jointly prepare interview outlines and topic lists in advance of each session. Each firm will circulate its proposed questions to the other no later than three business days prior to the scheduled interview, and the firms will consolidate the outlines into a single joint interview guide for use during the session.

Detailed interview notes will be taken by associates from each firm. On behalf of C&H, Claire Dempsey and/or Audrey Zhou will be responsible for note-taking; on behalf of V&K, Priya Ranganathan will serve in this capacity. Interview notes will be circulated between counsel within forty-eight (48) hours following the conclusion of each interview session for review, comment, and supplementation. These notes will form part of the due diligence record and will be incorporated into the Defense Memorandum.

All interviews will be supplemented by follow-up questions in writing to the extent that additional information or clarification is necessary following a session. Written follow-up questions and responses will be documented and preserved as part of the due diligence record.

The Company's German counsel (Bähr Stein) will participate in interview sessions involving matters of German corporate governance, Aktiengesetz requirements, Supervisory Board matters, and other issues requiring analysis under German law. Similarly, the Underwriters' German counsel (Prumvane Thornton) will participate in such sessions to the extent appropriate.

IV. Specialist Due Diligence Sessions

In addition to the general document review and management interviews described above, we propose the following specialist due diligence sessions to address areas requiring focused expertise:

A. Tax Due Diligence

Tax due diligence will be led by Leonard Cross, Specialist Partner, Tax, at Calderwood & Harkness LLP. The principal topics to be addressed in the tax due diligence sessions include:

(a) PFIC Analysis. A detailed analysis of whether Halcyon constitutes a Passive Foreign Investment Company ("PFIC") for purposes of Sections 1291 through 1298 of the Internal Revenue Code of 1986, as amended, for each of the fiscal years ended December 31, 2023, 2024, and 2025. Our preliminary analysis, based on information provided to date, indicates that Halcyon is not a PFIC for any of the relevant tax years, as the Company satisfies the active business exception — specifically, the Company derives less than 25% of its gross income from passive sources and holds less than 50% of its assets (on a quarterly weighted average basis) in passive assets. This preliminary conclusion must be confirmed through the tax due diligence process and will form the basis of the PFIC disclosure to be included in the prospectus.

(b) US/German Tax Treaty Implications. An analysis of the application of the Convention between the United States of America and the Federal Republic of Germany for the Avoidance of Double Taxation and the Prevention of Fiscal Evasion with respect to Taxes on Income and Capital and to Certain Other Taxes (the "US/Germany Tax Treaty") to the Offering and to distributions on the ADSs. Under Article 10 of the US/Germany Tax Treaty, the statutory German withholding tax rate of 26.375% (including the solidarity surcharge) applicable to dividends paid to non-resident shareholders is reduced to 15% for US resident holders who are entitled to claim treaty benefits, subject to compliance with applicable limitation-on-benefits provisions.

(c) Qualified Intermediary Analysis. An analysis of the status and obligations of Meridian Trust Company, N.A., as depositary bank, in its capacity as a Qualified Intermediary for purposes of withholding on distributions to ADS holders.

V&K's tax professionals are invited to participate in the tax due diligence sessions to the extent relevant to the Underwriters' due diligence defense and to the review of tax-related disclosure in the prospectus.

B. Intellectual Property and Technology

We propose a specialist intellectual property and technology review session to be conducted with Dr. Marcus Helder, the Company's Chief Technology Officer, and members of the Company's internal IP team. This session will address the Company's patent portfolio, freedom-to-operate analyses, IP prosecution strategy, IP litigation history, and the commercial significance of the Company's proprietary SiC and GaN technologies. V&K will have full access to the patent portfolio summary, freedom-to-operate analyses, and IP litigation history maintained in the Data Room. The IP specialist session is currently targeted for the week of February 24–26, 2026.

C. Regulatory and Export Controls

Given the heightened regulatory environment applicable to the semiconductor industry, we propose a joint session focused on the Company's compliance with semiconductor export control regulations, including the US Export Administration Regulations (EAR), the International Traffic in Arms Regulations (ITAR), and EU dual-use export control regulations. This session will also address OFAC sanctions compliance and will give particular attention to the operations, customer base, and compliance posture of Halcyon Shanghai Semiconductor Co., Ltd. in the People's Republic of China. Both C&H and V&K will participate in this session, and German counsel will be involved with respect to EU-side regulatory issues. This session is currently targeted for the week of March 3–5, 2026.

D. Environmental. We will conduct a focused review of environmental permits and compliance records for all fabrication and assembly facilities operated by the Company and its subsidiaries, with particular emphasis on the Dresden Fab 3 facility (currently under construction) and chemical handling and waste disposal practices in semiconductor fabrication processes. Given the significance of the Company's manufacturing operations, we will consider whether a site visit to the Dresden facilities (operated by Halcyon Power Solutions GmbH, located at Königsbrücker Straße 180, 01099 Dresden, Germany) is warranted, and we would welcome V&K's view on whether to include such a visit in the due diligence plan.

V. Third-Party Due Diligence

In addition to the document review, management interviews, and specialist sessions described above, the following third-party due diligence activities will be conducted:

Background Checks. Background checks will be conducted on all directors and senior officers of the Company, including Dr. Friedrich Wendt (CEO), Katarina Dalmqvist (CFO), Dr. Marcus Helder (CTO), Ingrid Baumann (COO), Wilhelm Ostermann (General Counsel), and Prof. Dr. Anneliese Voss (Chair of the Supervisory Board), as well as the principals of the selling shareholders, namely Margarethe Wendt (Managing Director of Rheintal Industrieholding GmbH) and Henrik Sørensen (Managing Partner of Kestrel Capital Partners AG). These background checks will encompass public records searches, litigation history, regulatory actions, and bankruptcy filings in all relevant jurisdictions. The results will be coordinated with V&K for purposes of the FINRA filing and the information required in connection with the Underwriters' obligations under FINRA Rule 5110.

Lien and Judgment Searches. Lien and judgment searches will be conducted on Halcyon and each of its material subsidiaries in all relevant jurisdictions, including UCC searches in Delaware and California (for Halcyon Semiconductor USA Inc.), and equivalent searches in Germany, Singapore, the PRC, and the Czech Republic, to the extent available and customary.

Verification of Existing Listing Status. We will independently verify Halcyon's existing listing status on the Frankfurt Stock Exchange (Frankfurter Wertpapierbörse) in the Prime Standard segment of the Regulated Market (Regulierter Markt), where the Company's ordinary shares are currently admitted to trading under the ticker symbol "HCY" (FRA: HCY).

Confirmation of Identifiers. We will confirm the Company's Legal Entity Identifier (LEI: 5299007KBTVZ3XQHGL48) and the Employer Identification Number (EIN: 84-3927561) assigned to Halcyon Semiconductor USA Inc.

VI. Section 11 and Section 12(a)(2) Defense Memorandum Framework

A. Legal Standard

As both of our firms are well aware, the due diligence investigation described in this Protocol is undertaken with a view toward establishing and preserving the Underwriters' defense under Section 11(b)(3) of the Securities Act. Under that provision, an underwriter may avoid liability for material misstatements or omissions in a registration statement by demonstrating that, after reasonable investigation, such underwriter had reasonable ground to believe, and did believe, at the time the registration statement became effective, that the statements contained therein were true and that there was no omission of a material fact required to be stated therein or necessary to make the statements therein not misleading.

The standard of reasonableness applicable to the due diligence defense is that required of a prudent person in the management of his own property. This standard is deliberately flexible, recognizing that the scope and depth of the investigation required will vary depending on the circumstances of the particular offering, including the nature and complexity of the issuer's business, the magnitude of the offering, and the materiality of the information at issue.

It is important to note the distinction between "expertised" portions and "non-expertised" portions of the Registration Statement. The "expertised" portions consist of those portions of the Registration Statement that purport to be made on the authority of an expert, principally the audited financial statements and the auditor's report thereon. With respect to these portions, the underwriter's defense requires only that the underwriter had no reasonable ground to believe, and did not believe, that such statements were untrue or that material facts were omitted — a "reliance" standard that does not require independent investigation. With respect to all other portions of the Registration Statement and prospectus (the "non-expertised" portions), including the business description, risk factors, management's discussion and analysis, and other narrative disclosure, the underwriter bears the higher burden of demonstrating that it conducted a reasonable investigation and had reasonable ground to believe in the accuracy and completeness of the statements made.

In addition to Section 11 liability, the Underwriters face potential liability under Section 12(a)(2) of the Securities Act, which imposes liability on any person who offers or sells a security by means of a prospectus or oral communication that contains a material misstatement or omission. Section 12(a)(2) provides a defense for sellers who can establish that they did not know, and in the exercise of reasonable care could not have known, of the misstatement or omission. The due diligence investigation described herein is intended to establish the evidentiary foundation for this "reasonable care" defense as well.

We note for the record that the Registration Statement on Form F-1 will cover the offering of a total of 21,400,000 ADSs in the base deal (consisting of 15,000,000 primary ADSs and 6,400,000 secondary ADSs), together with an overallotment option (the "Greenshoe Option") granted to the Underwriters to purchase up to an additional 3,210,000 ADSs (representing 15% of the base deal) from the Company, exercisable for a period of 30 days following pricing. If the Greenshoe Option is exercised in full and assuming an offering price of $42.00 per ADS (the midpoint of the proposed range), the maximum aggregate offering size would be approximately $1,034,812,600.

B. Proposed Structure of the Defense Memorandum

Both C&H and V&K will jointly maintain the Due Diligence Defense Memorandum, which will serve as the comprehensive documentary record of the scope and thoroughness of the due diligence investigation conducted in connection with the Offering. The Defense Memorandum will be a living document that is updated and supplemented throughout the due diligence process from commencement through closing. We propose that the Defense Memorandum be organized into the following sections:

1. Chronology. A detailed timeline of all due diligence activities conducted from the date of C&H's initial engagement by the Company (January 12, 2026) through the closing of the Offering (targeted for July 6, 2026). The chronology will include the dates of all document review sessions, management interviews, accountants' sessions, specialist sessions, and other material due diligence activities, together with a summary of the participants in each activity and the topics addressed.

2. Document Review Log. A comprehensive index of all documents reviewed in the Data Room, organized by category in accordance with the Request List. Each entry will include the document identification number assigned in the Data Room, a brief description of the document, the name of the reviewer(s), the date of review, and notation of any issues flagged for further investigation or disclosure consideration.

3. Management Interview Summaries. Summaries of each management interview session, including the date and location of the interview, the identity of all attendees, the topics covered, key information elicited, and any follow-up items identified during or after the session. These summaries will be prepared based on the detailed interview notes taken by associates from each firm, as described in Section III.C above.

4. Accountants' Session Notes. Records of all meetings and discussions with Blackmere & Whitfield regarding auditing procedures, the scope and results of the audit, significant accounting policies and estimates, comfort letter procedures, and the verification of financial data included in the Registration Statement.

5. Specialist Session Notes. Records of the specialist due diligence sessions described in Section IV above, including the tax due diligence sessions, IP and technology review sessions, regulatory and export control sessions, and environmental review sessions.

6. Third-Party Verification Records. Results of the background checks, lien and judgment searches, verification of the Company's listing status and identifiers, and other third-party due diligence activities described in Section V above.

7. Issue Resolution Log. Documentation of the identification, investigation, and resolution of each material issue identified during the course of the due diligence investigation. For each issue, the log will record the nature of the issue, the steps taken to investigate it, the conclusion reached, and, where applicable, the manner in which the issue was addressed through prospectus disclosure or otherwise resolved.

8. Cross-Reference to Prospectus Disclosure. A detailed mapping of due diligence findings to specific sections of the prospectus disclosure, including the risk factors, business description, management's discussion and analysis of financial condition and results of operations ("MD&A"), related-party transactions, compensation discussion, and other relevant sections. This cross-reference will demonstrate the connection between the due diligence investigation and the disclosure ultimately included in the Registration Statement and prospectus.

C. Allocation of Responsibility

The respective responsibilities of C&H and V&K in connection with the preparation of the Registration Statement and the due diligence investigation are as follows:

C&H, as issuer's US securities counsel, will take primary responsibility for preparing the initial drafts of the Registration Statement on Form F-1 and the prospectus forming part thereof, coordinating with the Company's management team and German counsel (Bähr Stein) on all aspects of drafting. C&H will also coordinate with the Company's financial advisors and auditors on the presentation of financial information and MD&A disclosure.

V&K, as the Underwriters' US counsel, will independently verify the adequacy and completeness of the disclosure in the Registration Statement and prospectus from the perspective of the Underwriters' due diligence defense. V&K will review each draft of the Registration Statement and provide comments reflecting the Underwriters' perspective and V&K's independent assessment of the thoroughness of the due diligence record.

Both firms will contribute to the joint Defense Memorandum. C&H will prepare the initial drafts of the Defense Memorandum sections based on its role as coordinator of the due diligence process, and V&K will review, supplement, and comment on each draft to ensure that the Defense Memorandum accurately reflects the totality of the due diligence investigation from both the issuer's and the Underwriters' perspectives.

At closing, each firm will independently prepare and deliver its own negative assurance (10b-5) letter. C&H, as issuer's US counsel, will deliver a 10b-5 letter addressed to the Underwriters. V&K, as the Underwriters' US counsel, will deliver a separate 10b-5 letter addressed to the Underwriters. The preparation and delivery of these letters are independent obligations of each firm and reflect each firm's independent assessment of the adequacy of the due diligence investigation and the accuracy of the disclosure in the Registration Statement.

In addition, Prumvane Thornton LLP (Dr. Stefan Braun, Partner) will contribute German-law due diligence findings to the Defense Memorandum record, including its analysis of German corporate governance matters, compliance with the Aktiengesetz, and other matters of German law relevant to the Offering.

D. Timing and Updates

We propose the following schedule for the preparation and updating of the Defense Memorandum:

The first substantive draft of the Defense Memorandum, incorporating the results of the initial document review and the initial round of management interviews, will be prepared concurrently with the circulation of the first draft of the Registration Statement on Form F-1, which is targeted for March 9, 2026. An updated draft will be prepared following the all-parties drafting session scheduled for March 23–24, 2026, and a further update will be completed prior to the confidential submission of the Registration Statement to the SEC on April 14, 2026. The Defense Memorandum will be updated on an ongoing basis throughout the SEC comment process (with the first SEC comment letter estimated to be received on or about May 12, 2026, and Amendment No. 1 to the Registration Statement targeted for filing on May 26, 2026) and will be finalized in a closing version as of the closing date of the Offering on July 6, 2026.

VII. Confidentiality and Privilege

All due diligence work product, interview notes, specialist session records, and Defense Memorandum materials prepared by or on behalf of C&H, V&K, or any other counsel participating in the due diligence investigation are prepared in anticipation of potential litigation under the Securities Act and are protected by the attorney-client privilege and the attorney work-product doctrine. The parties shall take all necessary steps to preserve the privileged and confidential nature of these materials.

All materials prepared in connection with the due diligence investigation and the Defense Memorandum shall be prominently marked with the following legend:

"PRIVILEGED AND CONFIDENTIAL — ATTORNEY WORK PRODUCT"

The Defense Memorandum and all related work product shall not be shared with, or disclosed to, any third party other than the Underwriters (Westbridge Securities LLC, Pinnacle Morgan & Co., Inc., Andover Barcliffe Group Inc., and Northpointe Capital LLC) and their respective authorized personnel, without the prior written consent of both C&H and V&K. Any disclosure to any other party — including any regulatory authority, rating agency, or potential investor — must be approved in advance by both firms.

To the extent necessary to preserve the attorney-client privilege and work-product protection over joint due diligence work product shared between issuer's counsel and underwriters' counsel, the parties will enter into a common interest agreement (a "Common Interest Agreement") pursuant to which the parties agree that the sharing of privileged information between them in connection with the Offering does not constitute a waiver of any applicable privilege. We propose to discuss whether the execution of a separate Common Interest Agreement is necessary or advisable, and if so, to finalize such an agreement promptly.

VIII. Coordination with Other Advisors

In the course of the due diligence process, we anticipate coordination with the following additional advisors retained by the Company or the Underwriters:

Ashton & Burke Advisory GmbH (Lukas Frey, Managing Partner, Theatinerstraße 11, 80333 Munich, Germany) — Financial advisor to Halcyon. Ashton & Burke will provide valuation analyses, industry benchmarking, and market context to inform the due diligence sessions as requested by either C&H or V&K.

Bridgeport Investor Relations LLC (Thomas Harding, Senior Vice President, 350 Fifth Avenue, Suite 6820, New York, New York 10118) — US investor relations advisor to Halcyon. Bridgeport's work on investor messaging and positioning will be reviewed to ensure consistency with the prospectus disclosure and to avoid any inconsistencies between the Company's public investor communications and the Registration Statement.

Meridian Trust Company, N.A. (Patricia Novak, Vice President, Depositary Receipts, 101 Barclay Street, New York, New York 10286) — Depositary bank for the ADS program. Due diligence will be conducted on the deposit agreement mechanics, custodian arrangements, the process for issuance and cancellation of ADSs, voting procedures for ADS holders, and the depositary's obligations and rights under the deposit agreement.

Crestfield Transfer Services Inc. (Angela Moretti, Director, Corporate Actions, 6201 15th Avenue, Brooklyn, New York 11219) — Transfer agent and ADS registrar. Operational due diligence will be conducted on Crestfield's systems and procedures for the registration, transfer, and cancellation of ADSs and the maintenance of the ADS register.

Clearwater D&O Insurance Brokers Ltd. (Emma Callister, Vice President, Financial Lines) — Insurance broker for the Company's D&O program. Clearwater will assist in the review of the adequacy of the Company's D&O insurance program in light of the Offering, including the sufficiency of the $75,000,000 total program limits and the structure of the layered program. We note that the estimated annual premium for the current D&O program is approximately $2,800,000, and we will assess whether adjustments to the program are warranted in connection with the Company's transition to a publicly listed company in the United States.

IX. Proposed Due Diligence Calendar (Key Dates)

The following table sets forth the proposed due diligence calendar, incorporating the key dates and milestones discussed above. All dates are subject to adjustment based on the progress of the due diligence investigation, the SEC review process, and market conditions.

X. Contact Information

For purposes of due diligence coordination, the primary contacts at each firm are as follows:

Calderwood & Harkness LLP

Vivienne St. Claire, Responsible Partner

Email: vivienne.stclaire@calderwoodharkness.com

Claire Dempsey, Lead Associate

Email: claire.dempsey@calderwoodharkness.com

Audrey Zhou, Working Associate

Email: audrey.zhou@calderwoodharkness.com

Calderwood & Harkness LLP One Liberty Plaza, 42nd Floor New York, New York 10006 Telephone: (212) 558-4000

Varen & Kessler LLP

Martin Ashford, Partner

Email: mashford@varenkessler.com

Priya Ranganathan, Senior Associate

Email: pranganathan@varenkessler.com

Varen & Kessler LLP 51 West 52nd Street New York, New York 10019

All due diligence-related correspondence, document requests, and scheduling communications should be directed to the contacts listed above. We ask that, to the extent practicable, all communications related to due diligence be made in writing (including by email) so that a complete record of the due diligence process is maintained.

XI. Request for Confirmation

We respectfully request that V&K confirm its agreement to the Protocol and Defense Memorandum framework set forth in this letter, together with any proposed modifications or additions, on or before February 3, 2026. We are available at your convenience to schedule a call or meeting to discuss any points requiring further coordination or clarification.

We recognize that the Protocol described herein represents the parties' initial framework for the conduct of due diligence, and that the scope and sequence of due diligence activities may evolve as the process unfolds and new information comes to light. Accordingly, the Protocol may be amended at any time by mutual written agreement of C&H and V&K.

We look forward to working with you and your team throughout this process.

Very truly yours,

CALDERWOOD & HARKNESS LLP

By: ________

Vivienne St. Claire Partner

cc (via email):

Robert Adeyemi, Partner, Calderwood & Harkness LLP Claire Dempsey, Associate, Calderwood & Harkness LLP Audrey Zhou, Associate, Calderwood & Harkness LLP Leonard Cross, Partner, Calderwood & Harkness LLP Wilhelm Ostermann, General Counsel, Halcyon Semiconductor AG Dr. Christoph Maurelban, Partner, Bähr Stein Rechtsanwälte PartGmbB Dr. Stefan Braun, Partner, Prumvane Thornton LLP Jonathan Hartwell, Managing Director, Westbridge Securities LLC

This letter and all attachments hereto are privileged and confidential and are prepared in anticipation of litigation. This letter constitutes attorney work product and is protected by the attorney-client privilege and the work-product doctrine. Any unauthorized review, use, disclosure, or distribution is prohibited.

Metric	FY2023	FY2024	FY2025 (Unaudited)
Revenue	€3,214M	€3,508M	€3,820M
EBITDA	€869M	€966M	€1,069M
EBITDA Margin	27.0%	27.5%	28.0%
Net Income	€482M	€541M	€612M
Total Assets	—	—	€7,450M
Total Debt	—	—	€890M
Cash and Cash Equivalents	—	—	€740M
Capital Expenditures	—	—	€820M
Milestone	Target Date
Initial draft of Defense Memorandum outline	February 28, 2026
First substantive draft (incorporating document review and initial interview notes)	March 9, 2026
Updated draft following all-parties drafting session	March 23–24, 2026
Pre-filing update	April 14, 2026
Ongoing updates through SEC comment process	May–June 2026
Amendment No. 1 update	May 26, 2026
Public filing update	June 8, 2026
Final update and closing version	July 6, 2026
Activity	Target Date
Due diligence commencement / Data Room access	January 27, 2026
First management interview round	February 3–14, 2026
Initial accountants' session (Blackmere & Whitfield)	February 10–12, 2026
Tax due diligence session (Leonard Cross, C&H)	February 17–19, 2026
IP / technology specialist session	February 24–26, 2026
Defense Memorandum outline draft	February 28, 2026

Regulatory / export controls session	March 3–5, 2026
First draft F-1 circulation	March 9, 2026
All-parties drafting session	March 23–24, 2026
Pre-filing management bring-down interview	April 7–9, 2026
Confidential submission to SEC	April 14, 2026
SEC first comment letter (estimated)	May 12, 2026
Amendment No. 1 filing	May 26, 2026
Public filing of Registration Statement	June 8, 2026
Pre-pricing management bring-down interview	June 16–18, 2026
SEC declaration of effectiveness (target)	June 22, 2026
Roadshow launch	June 23, 2026
Pricing	July 1, 2026
Closing bring-down interview	July 3, 2026
Closing / Settlement (T+2)	July 6, 2026

PRIVILEGED AND CONFIDENTIAL — ATTORNEY WORK PRODUCT
CALDERWOOD & HARKNESS LLP One Liberty Plaza, 42nd Floor New York, New York 10006
Telephone: (212) 558-4000 Facsimile: (212) 558-3588 www.calderwoodharkness.com
January 27, 2026
VIA EMAIL AND OVERNIGHT COURIER
Martin Ashford, Esq. Partner, Capital Markets Varen & Kessler LLP 51 West 52nd Street New York, New York 10019
cc: Priya Ranganathan, Senior Associate, Varen & Kessler LLP (via email: pranganathan@varenkessler.com)
Re: Halcyon Semiconductor Aktiengesellschaft — US Initial Public Offering of American Depositary Shares; Due Diligence Protocol and Section 11/12 Defense Memorandum Framework
C&H Matter No. 1032-00003
Dear Martin:
I. Introduction and Purpose
As you know, this firm serves as US securities counsel to Halcyon Semiconductor Aktiengesellschaft ("Halcyon" or the "Company"), a German Aktiengesellschaft (Aktiengesellschaft nach deutschem Recht) with its registered office in Munich, Germany (registered in the Commercial Register (Handelsregister) of the Local Court (Amtsgericht) of Munich under registration number HRB 217458), in connection with the proposed US initial public offering (the "Offering") of American Depositary Shares ("ADSs"), each representing two ordinary shares (Stammaktien) of the Company, through a Level III American Depositary Receipt program sponsored by the Company.
We understand that your firm, Varen & Kessler LLP ("V&K"), serves as US counsel to the underwriting syndicate in connection with the Offering. The underwriting syndicate is led by Westbridge Securities LLC, acting as lead left bookrunner and representative of the several underwriters (the "Representative"), together with Pinnacle Morgan & Co., Inc. and Andover Barcliffe Group Inc., each acting as joint bookrunners, and Northpointe Capital LLC, acting as co-manager (collectively, the "Underwriters").
The purpose of this letter is twofold. First, we write to establish a mutually agreed due diligence protocol (the "Protocol") that will govern the joint and independent due diligence activities to be undertaken by both Calderwood & Harkness LLP ("C&H") and V&K in connection with the Offering. Second, we seek to outline the framework for the due diligence defense memorandum (the "Due Diligence Defense Memorandum" or "Defense Memorandum") to be prepared jointly by our respective firms in connection with potential liability under Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended (the "Securities Act").
As discussed at the organizational meeting held on January 22, 2026, at which representatives of C&H, V&K, the Company, the Underwriters, and the respective German counsel for the issuer and the underwriters participated, the parties agreed on the general framework and indicative timeline for the due diligence investigation. We confirmed at that meeting that due diligence would formally commence on January 27, 2026 — the date of this letter — and that access to the Company's virtual data room would be provided to all counsel and relevant advisors on or about this date.
The Company intends to file a Registration Statement on Form F-1 (the "Registration Statement") under the Securities Act in connection with the Offering, with a targeted confidential submission to the US Securities and Exchange Commission (the "SEC") on or about April 14, 2026, pursuant to the accommodations available to emerging growth companies and foreign private issuers. A thorough and well-documented due diligence record must be established well in advance of such confidential submission, and must thereafter be maintained and updated through the effectiveness of the Registration Statement, pricing, and closing of the Offering.
As discussed at the organizational meeting, the Offering targets aggregate gross proceeds of approximately $900,000,000. The Offering will consist of (a) a primary offering of 15,000,000 ADSs, representing 30,000,000 newly issued ordinary shares of the Company, and (b) a secondary offering of 6,400,000 ADSs, representing 12,800,000 existing ordinary shares to be sold by the selling shareholders, namely Rheintal Industrieholding GmbH (selling 4,250,000 ADSs representing 8,500,000 existing shares) and Kestrel Capital Partners AG (selling 2,150,000 ADSs representing 4,300,000 existing shares). Each ADS will represent two ordinary shares (the "ADS Ratio"), with a proposed price range of $39.00 to $45.00 per ADS. The Company intends to apply for listing of the ADSs on the Nasdaq Global Select Market under the ticker symbol "HCYN."
We set forth below the detailed provisions of the Protocol and the Defense Memorandum framework for your review and confirmation.
II. Scope of Due Diligence
A. General Principles
The due diligence investigation contemplated by this Protocol is intended to serve several critical purposes. Foremost among them, the investigation must provide a reasonable basis for the Underwriters to establish a defense under Section 11(b)(3) of the Securities Act (commonly referred to as the "due diligence defense") in the event of any claim brought under Section 11 of the Securities Act with respect to alleged material misstatements or omissions in the Registration Statement. Equally important, the investigation must be sufficiently thorough and well-documented to permit both issuer's counsel (C&H) and underwriters' counsel (V&K) to deliver their respective negative assurance letters (commonly referred to as "10b-5 letters" or "10b-5 disclosure letters") at closing, which is currently targeted for July 6, 2026.
As both firms are aware, Halcyon qualifies as a "foreign private issuer" as defined in Rule 3b-4 under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and the due diligence investigation must accordingly address both US securities law requirements and the cross-border aspects inherent in a transaction involving a German Aktiengesellschaft. The Company maintains a complex organizational structure with subsidiaries and operations in multiple jurisdictions, including Germany (where the parent entity and its principal fabrication and R&D operations are domiciled), the United States (through its wholly owned subsidiary Halcyon Semiconductor USA Inc., a Delaware corporation with operations in California), Singapore (through Halcyon Asia Pacific Pte. Ltd.), the People's Republic of China (through Halcyon Shanghai Semiconductor Co., Ltd.), and the Czech Republic (through Halcyon Automotive Components s.r.o., based in Brno). Each of these jurisdictions presents unique legal, regulatory, and operational considerations that must be addressed in the course of the due diligence investigation.
To facilitate efficient and comprehensive document review, the Company has established a virtual data room (the "Data Room") hosted on the Thackeray Solutions platform. All documents uploaded by the Company and its advisors will be indexed and tracked via the master due diligence request list (the "Request List") previously circulated by C&H to the Company, Bähr Stein Rechtsanwälte PartGmbB ("Bähr Stein," German counsel to the Company), and the respective working groups. Both C&H and V&K, together with their respective associates and other authorized personnel, shall have full access to the Data Room throughout the due diligence period, subject to the confidentiality and privilege protections described in Section VII below.
B. Document Review
Both C&H and V&K shall conduct a comprehensive review of all documents that are responsive to the Request List previously circulated by C&H to the Company and Bähr Stein (Dr. Christoph Maurelban and Johanna Weiß). The documents requested and to be reviewed are organized into the following principal categories:
1. Corporate and Organizational Documents. This category encompasses the foundational corporate documents of Halcyon and each of its material subsidiaries. For the parent entity, the review will include the Company's Satzung (articles of association) in their current form as adopted by the most recent shareholders' meeting, extracts from the Commercial Register (Handelsregisterauszug) of the Amtsgericht München, the Company's current shareholder register (Aktienregister), and complete minute books of the Vorstand (Management Board) and Aufsichtsrat (Supervisory Board) for the three fiscal years ended December 31, 2023, 2024, and 2025, together with any minutes from the current fiscal year through the date of closing. For each material subsidiary, the review will include all organizational and governing documents, including: (a) the certificate of incorporation, bylaws, and minutes of the board of directors and stockholders of Halcyon Semiconductor USA Inc. (incorporated in the State of Delaware); (b) the Gesellschaftsvertrag and related organizational documents of Halcyon Power Solutions GmbH (registered in Dresden, Germany); (c) the memorandum and articles of association of Halcyon Asia Pacific Pte. Ltd. (incorporated in Singapore); (d) the articles of association and business license of Halcyon Shanghai Semiconductor Co., Ltd. (established under the laws of the People's Republic of China with its registered office in Shanghai); and (e) the organizational documents of Halcyon Automotive Components s.r.o. (registered in Brno, Czech Republic). We will also review all intercompany agreements, capital contribution records, and organizational charts.
2. Material Contracts. We will conduct a thorough review of all material contracts to which the Company or any of its subsidiaries is a party, including without limitation: supply agreements with key raw materials and equipment suppliers (including silicon carbide wafer suppliers and epitaxial growth equipment vendors); customer contracts, particularly long-term supply arrangements with automotive and industrial OEM customers; joint development agreements and strategic collaboration arrangements; technology license agreements (both inbound and outbound); the Company's existing revolving credit facility (noting that the Company has disclosed that approximately $100,000,000 of the net proceeds from the primary offering will be allocated to the partial repayment of outstanding borrowings under this facility); and any agreements containing change-of-control provisions, anti-assignment clauses, or other restrictions that may be triggered by the Offering or the resultant change in the Company's shareholder composition.
3. Intellectual Property. Given that Halcyon's competitive position in the power semiconductor market is critically dependent on its technology portfolio, the IP review constitutes one of the most important components of the due diligence process. This review will encompass the Company's entire patent portfolio relating to silicon carbide (SiC) and gallium nitride (GaN) power semiconductor technologies, including all issued patents, pending patent applications, and continuations in each relevant jurisdiction. The review will also cover trade secret protections and policies, trademark registrations and applications, domain names, IP licensing agreements (both as licensor and licensee), and any pending or threatened intellectual property litigation or disputes. We will examine the Company's freedom-to-operate analyses and any third-party opinions of counsel regarding non-infringement or invalidity.
4. Litigation and Regulatory Proceedings. This category includes all pending and threatened litigation involving the Company or any subsidiary, all pending or concluded arbitration proceedings, and all governmental or regulatory investigations, inquiries, or enforcement actions. We will request detailed descriptions of each matter, together with copies of complaints, answers, counterclaims, significant motion papers, and settlement agreements. We will also review the Company's litigation reserves and assess the adequacy of the Company's disclosure of litigation-related contingencies.
5. Environmental and Manufacturing Compliance. Given the nature of semiconductor fabrication, which involves the use of hazardous chemicals and materials, environmental compliance is a critical area of due diligence. We will review all environmental permits, licenses, and authorizations held by the Company and its subsidiaries for each manufacturing facility, including: the Company's headquarters and principal fabrication facility in Munich; the Dresden Fab 2 facility (operated by Halcyon Power Solutions GmbH); the Dresden Fab 3 facility, which is currently under construction and represents a major component of the Company's use of proceeds; and the assembly and test facility in Brno, Czech Republic (operated by Halcyon Automotive Components s.r.o.). The review will also encompass hazardous materials handling protocols, waste disposal practices, environmental impact assessments, and any past or present environmental remediation obligations.
6. Employee Benefit Plans and Compensation. We will review all material employee benefit plans and compensation arrangements maintained by the Company and its subsidiaries, including both German and non-German plans. Of particular significance, we will review the documentation relating to the Halcyon Employee Stock Ownership Trust (the "ESOT"), which currently holds approximately 3.1% of the Company's outstanding share capital (approximately 6,665,000 ordinary shares), including the trust deed, allocation policies, and the impact of the Offering on the ESOT's holdings. We will also review executive compensation arrangements for each member of the Vorstand, including Dr. Friedrich Wendt (Chief Executive Officer / Vorstandsvorsitzender), Katarina Dalmqvist (Chief Financial Officer / Finanzvorstand), Dr. Marcus Helder (Chief Technology Officer), Ingrid Baumann (Chief Operating Officer), and Wilhelm Ostermann (General Counsel / Chefjustitiar), as well as compensation arrangements for members of the Aufsichtsrat.
7. Related-Party Transactions. We will conduct a thorough review of all transactions between the Company and its related parties, with particular focus on transactions with Rheintal Industrieholding GmbH ("Rheintal"), the Wendt family holding company that currently holds approximately 22.3% of the Company's outstanding share capital and is expected to hold approximately 16.1% following the Offering. Rheintal is controlled by Margarethe Wendt, who is the sister of the Company's Chief Executive Officer, Dr. Friedrich Wendt. This familial relationship and the significant shareholding of Rheintal necessitate a heightened level of scrutiny of all transactions between the Company and Rheintal, as well as careful consideration of disclosure obligations under Item 7.B of Form 20-F (as incorporated by reference into Form F-1). We will also review relationships and transactions involving members of the Supervisory Board.
8. Sanctions, Anti-Corruption, and Export Controls. Given the Company's global operations, and in particular its subsidiary in Shanghai, China, this area of due diligence is of heightened importance. The review will encompass the Company's compliance with US sanctions administered by the Office of Foreign Assets Control ("OFAC"), EU sanctions regulations, the US Foreign Corrupt Practices Act ("FCPA"), the UK Bribery Act 2010, and applicable export control regulations, including the US Export Administration Regulations ("EAR"), the International Traffic in Arms Regulations ("ITAR"), and EU dual-use export control regulations. We will give particular attention to Halcyon Shanghai Semiconductor Co., Ltd.'s operations, customer base, and compliance with applicable restrictions on the export and re-export of semiconductor technology and products.
9. Financial and Tax Records. This category includes all audited consolidated financial statements of the Company prepared in accordance with International Financial Reporting Standards as issued by the International Accounting Standards Board ("IFRS") for the fiscal years ended December 31, 2023 and December 31, 2024, together with the unaudited consolidated financial statements for the fiscal year ended December 31, 2025. The Company has informed us that its unaudited financial results for FY2025 reflect revenue of approximately €3,820 million, EBITDA of approximately €1,069 million (representing an EBITDA margin of approximately 28.0%), and net income of approximately €612 million. We will also review management accounts, budgets, projections, and related financial planning materials, as well as tax returns filed in each relevant jurisdiction, transfer pricing documentation, and materials relevant to the Passive Foreign Investment Company ("PFIC") analysis that will be included in the prospectus.
10. Insurance Program. We will review the Company's comprehensive insurance program, with particular emphasis on the adequacy of the Company's directors' and officers' liability insurance ("D&O Insurance") in light of the Offering. We understand that the Company's current D&O insurance program provides total limits of $75,000,000, structured across four layers as follows: (i) Thornhill Assurance plc as primary insurer, providing a limit of $15,000,000; (ii) Arcadian Indemnity Corp. as first excess insurer, providing $20,000,000 in excess of $15,000,000; (iii) Helmsman Re Ltd. as second excess insurer, providing $20,000,000 in excess of $35,000,000; and (iv) Nordic Specialty Insurance SE as third excess insurer, providing $20,000,000 in excess of $55,000,000. We will also review the Company's property insurance, product liability insurance, and general commercial liability insurance policies.
Both C&H and V&K shall independently review documents in the Data Room. C&H will prepare and share due diligence memoranda on each of the above categories as the document review progresses, identifying key findings, areas of concern, and disclosure implications. V&K will conduct its own independent review of the Data Room documents and will supplement C&H's memoranda as needed from the perspective of the Underwriters' due diligence defense.
With respect to documents governed by German law or requiring analysis under German corporate or regulatory law, the document review will be coordinated with Bähr Stein Rechtsanwälte PartGmbB (issuer's German counsel; Dr. Christoph Maurelban, Partner, and Johanna Weiß, Senior Associate) and Prumvane Thornton LLP (underwriters' German counsel; Dr. Stefan Braun, Partner, Frankfurt office at Neue Mainzer Straße 52, 60311 Frankfurt am Main). Each German counsel will prepare German-law due diligence reports on matters within their respective scope and will coordinate with their US counterparts to ensure that all cross-border issues are addressed comprehensively.
C. Financial Due Diligence
Financial due diligence will be conducted in close coordination with the Company's independent auditors, Blackmere & Whitfield LLP (the "Auditors"). The Company's audit is led by Graham Templeton, Partner, based in the Blackmere & Whitfield New York office at 7 Times Square, New York, New York 10036, with Dieter Kaufmann serving as Lead Engagement Partner in the Blackmere & Whitfield GmbH Wirtschaftsprüfungsgesellschaft Munich office at Ganghoferstraße 29, 80339 Munich, Germany.
Both C&H and V&K will participate in auditor due diligence sessions (commonly referred to as "accountants' sessions") to be scheduled with the Auditors at appropriate intervals throughout the due diligence process. The topics to be addressed at these sessions will include, without limitation:
(a) the scope and procedures of the audit of the Company's IFRS consolidated financial statements for FY2023 and FY2024, including any changes in the scope of the audit from prior years;
(b) significant accounting policies and estimates applied by the Company, including those involving management judgment, and any changes in accounting policies or estimates during the relevant periods;
(c) revenue recognition practices, including the recognition of revenue from long-term supply contracts, licensing arrangements, and development agreements;
(d) material audit adjustments, proposed adjustments that were not recorded, and significant findings or recommendations communicated to the Company's management or Audit Committee;
(e) the procedures to be followed in connection with the comfort letter to be delivered by the Auditors to the Underwriters at pricing and closing, in accordance with the professional standards set forth in Statement on Auditing Standards No. 72 ("SAS 72") and, to the extent applicable, International Standard on Assurance Engagements 3000 ("ISAE 3000");
(f) the PCAOB registration status of Blackmere & Whitfield GmbH Wirtschaftsprüfungsgesellschaft and any limitations on the PCAOB's ability to inspect the auditor's workpapers; and
(g) the auditor's assessment of the Company's internal control over financial reporting, recognizing that the Company's first obligation to include a management assessment of internal controls under Section 404(a) of the Sarbanes-Oxley Act of 2002 will apply for the fiscal year ending December 31, 2026, and the first obligation to include an attestation report of the independent auditor under Section 404(b) will apply for the fiscal year ending December 31, 2027.
The key financial data points to be verified through the financial due diligence process include the following:
We propose the following schedule for accountants' sessions: (i) an initial accountants' session during the week of February 10–12, 2026, within approximately two weeks of the commencement of due diligence; (ii) a follow-up session to be held prior to the circulation of the first draft of the Form F-1, which is targeted for March 9, 2026; and (iii) a bring-down session to be held prior to closing to confirm the continued accuracy of the financial information in the Registration Statement and to address any developments since the prior session.
III. Management Interviews
A. Interview Schedule and Format
Management interviews (which, in subsequent rounds, are commonly referred to as "bring-down" interviews) constitute a core component of the due diligence process and will be conducted jointly by C&H and V&K. The participation of both issuer's counsel and underwriters' counsel in these sessions is critical to establishing a comprehensive due diligence record and to ensuring that all material information elicited during the interviews is available to both firms for purposes of prospectus drafting and the Defense Memorandum.
We propose the following schedule of management interview rounds:
(a) Initial Interview Round: To be completed during the period of February 3–14, 2026. This initial round is intended to elicit the foundational information necessary to inform the preparation of the first draft of the Form F-1, with a target circulation date of March 9, 2026.
(b) Pre-Filing Update Interview: To be conducted during the period of April 7–9, 2026, prior to the confidential submission of the Registration Statement to the SEC, currently targeted for April 14, 2026. The purpose of this session is to confirm the continued accuracy of the information previously provided by management and to identify any material developments since the initial interview round.
(c) Pre-Pricing Update Interview: To be conducted during the period of June 16–18, 2026, prior to the launch of the roadshow (targeted for June 23, 2026) and pricing (targeted for July 1, 2026). This session will address any developments arising during the SEC review process and will confirm the accuracy of the disclosure in the final prospectus.
(d) Closing Bring-Down Interview: To be conducted on or about July 3, 2026, prior to closing on July 6, 2026. This final interview will serve as the closing bring-down and will confirm that no material adverse changes have occurred since pricing and that all disclosure remains accurate and complete.
All interviews may be conducted by video conference or in person at the Company's headquarters at Maximilianstraße 72, 80539 Munich, Germany, or at C&H's offices in New York, as may be mutually agreed upon for each session. The Company's German counsel (Bähr Stein) and the Underwriters' German counsel (Prumvane Thornton) will participate simultaneously in sessions involving matters of German corporate governance, Aktiengesetz requirements, and Supervisory Board matters, as appropriate.
B. Proposed Interviewees and Topics
We propose the following interviews with members of the Company's management, Supervisory Board, and selling shareholder representatives, organized by interviewee and the principal topics to be addressed:
1. Dr. Friedrich Wendt, Chief Executive Officer (*Vorstandsvorsitzender*). Dr. Wendt will be interviewed regarding the Company's overall corporate strategy and vision; the competitive landscape in the global power semiconductor market, with particular focus on silicon carbide (SiC) and gallium nitride (GaN) technologies and the Company's competitive positioning relative to other market participants; key customer and supplier relationships and the concentration, duration, and terms of such relationships; the Company's expansion plans, including the construction and anticipated commissioning of the Dresden Fab 3 facility; the industry outlook across the Company's principal end markets, including automotive (electric vehicle power electronics), industrial automation, and renewable energy applications; and the nature, terms, and history of related-party transactions between the Company and Rheintal Industrieholding GmbH, including any ongoing commercial arrangements and the rationale for the selling shareholder transaction.
2. Katarina Dalmqvist, Chief Financial Officer (*Finanzvorstand*). Ms. Dalmqvist will be interviewed regarding the Company's financial performance and trends, including the revenue compound annual growth rate of approximately 9.0% achieved between FY2023 and FY2025; the proposed use of proceeds from the Offering, specifically the allocation of approximately $280,000,000 to the Fab 3 expansion, approximately $140,000,000 to GaN research and development initiatives, approximately $100,000,000 to the partial repayment of the Company's revolving credit facility, and the balance of approximately $87,950,000 (based on an assumed initial public offering price of $42.00 per ADS, which is the midpoint of the proposed range) to general corporate purposes and working capital; the Company's capital structure, including outstanding indebtedness and equity; foreign exchange exposure, with particular attention to the EUR/USD exchange rate (noted at 1.078 as of January 10, 2026) and the Company's hedging practices; material accounting judgments and estimates; and the Company's preparations for compliance with the internal control reporting requirements of Section 404 of the Sarbanes-Oxley Act (with Section 404(b) attestation first required for the fiscal year ending December 31, 2027).
3. Dr. Marcus Helder, Chief Technology Officer. Dr. Helder will be interviewed regarding the Company's technology and product roadmap; the composition and strategic significance of the Company's intellectual property portfolio, including its patent strategy for SiC and GaN technologies; the Company's research and development pipeline and prioritization of R&D investments; competitive technology risks and the pace of technological change in the power semiconductor industry; and export control implications arising from the Company's technology, including the classification of the Company's products and technical data under applicable US and EU export control regulations.
4. Ingrid Baumann, Chief Operating Officer. Ms. Baumann will be interviewed regarding the Company's manufacturing operations across all facilities, including the Munich headquarters and fabrication facility, the Dresden Fab 2 production facility, the Dresden Fab 3 facility currently under construction, and the Brno assembly and test facility; supply chain management practices, including raw material sourcing and supplier diversification; capacity utilization and planning; environmental, health, and safety compliance at each manufacturing facility; and the Company's global workforce, which currently comprises approximately 8,400 employees worldwide.
5. Wilhelm Ostermann, General Counsel (*Chefjustitiar*). Mr. Ostermann will be interviewed regarding all pending and threatened litigation and regulatory proceedings involving the Company or its subsidiaries; the Company's corporate governance structure, including the functioning of the two-tier board system (Vorstand and Aufsichtsrat) under German law and the Aktiengesetz; the terms and significance of the Company's material contracts; the Company's compliance programs, including those addressing anti-corruption, sanctions, and export controls; the Company's insurance program and the adequacy of coverage in light of the Offering; and regulatory approvals required in connection with the Offering, including any requirements under German or other applicable law.
6. Prof. Dr. Anneliese Voss, Chair of the Supervisory Board (*Aufsichtsratsvorsitzende*). Prof. Dr. Voss will be interviewed regarding the Supervisory Board's oversight of the Company's management and operations; the independence of the members of the Supervisory Board; the Company's governance practices and policies; the composition and responsibilities of the Supervisory Board's committees, including the audit committee; and the Supervisory Board's approval of the issuance of new shares in connection with the Offering and the exclusion of preemptive rights (Bezugsrechtsausschluss) under the Aktiengesetz.
7. Selling Shareholder Representatives. We propose interviews with the following representatives of the selling shareholders:
(a) Margarethe Wendt, Managing Director, Rheintal Industrieholding GmbH. Ms. Wendt will be interviewed regarding the ownership structure of Rheintal; the motivation for Rheintal's partial divestiture in the Offering (8,500,000 ordinary shares, equivalent to 4,250,000 ADSs); Rheintal's post-Offering intentions, including its anticipated retained holding of approximately 39,445,000 ordinary shares (representing approximately 16.1% of the Company's outstanding share capital on a post-Offering basis); and the nature of Ms. Wendt's family relationship with the Company's Chief Executive Officer, Dr. Friedrich Wendt (who is her brother), and any implications for governance and related-party matters.
(b) Henrik Sørensen, Managing Partner, Kestrel Capital Partners AG. Mr. Sørensen will be interviewed regarding Kestrel Capital Partners' original investment thesis for its investment in Halcyon; the motivation for Kestrel's partial divestiture in the Offering (4,300,000 ordinary shares, equivalent to 2,150,000 ADSs); and Kestrel's post-Offering plans, including its anticipated retained holding of approximately 16,555,000 ordinary shares (representing approximately 6.8% of the Company's outstanding share capital on a post-Offering basis).
C. Interview Procedures
To ensure the efficiency and completeness of the interview process, C&H and V&K will jointly prepare interview outlines and topic lists in advance of each session. Each firm will circulate its proposed questions to the other no later than three business days prior to the scheduled interview, and the firms will consolidate the outlines into a single joint interview guide for use during the session.
Detailed interview notes will be taken by associates from each firm. On behalf of C&H, Claire Dempsey and/or Audrey Zhou will be responsible for note-taking; on behalf of V&K, Priya Ranganathan will serve in this capacity. Interview notes will be circulated between counsel within forty-eight (48) hours following the conclusion of each interview session for review, comment, and supplementation. These notes will form part of the due diligence record and will be incorporated into the Defense Memorandum.
All interviews will be supplemented by follow-up questions in writing to the extent that additional information or clarification is necessary following a session. Written follow-up questions and responses will be documented and preserved as part of the due diligence record.
The Company's German counsel (Bähr Stein) will participate in interview sessions involving matters of German corporate governance, Aktiengesetz requirements, Supervisory Board matters, and other issues requiring analysis under German law. Similarly, the Underwriters' German counsel (Prumvane Thornton) will participate in such sessions to the extent appropriate.
IV. Specialist Due Diligence Sessions
In addition to the general document review and management interviews described above, we propose the following specialist due diligence sessions to address areas requiring focused expertise:
A. Tax Due Diligence
Tax due diligence will be led by Leonard Cross, Specialist Partner, Tax, at Calderwood & Harkness LLP. The principal topics to be addressed in the tax due diligence sessions include:
(a) PFIC Analysis. A detailed analysis of whether Halcyon constitutes a Passive Foreign Investment Company ("PFIC") for purposes of Sections 1291 through 1298 of the Internal Revenue Code of 1986, as amended, for each of the fiscal years ended December 31, 2023, 2024, and 2025. Our preliminary analysis, based on information provided to date, indicates that Halcyon is not a PFIC for any of the relevant tax years, as the Company satisfies the active business exception — specifically, the Company derives less than 25% of its gross income from passive sources and holds less than 50% of its assets (on a quarterly weighted average basis) in passive assets. This preliminary conclusion must be confirmed through the tax due diligence process and will form the basis of the PFIC disclosure to be included in the prospectus.
(b) US/German Tax Treaty Implications. An analysis of the application of the Convention between the United States of America and the Federal Republic of Germany for the Avoidance of Double Taxation and the Prevention of Fiscal Evasion with respect to Taxes on Income and Capital and to Certain Other Taxes (the "US/Germany Tax Treaty") to the Offering and to distributions on the ADSs. Under Article 10 of the US/Germany Tax Treaty, the statutory German withholding tax rate of 26.375% (including the solidarity surcharge) applicable to dividends paid to non-resident shareholders is reduced to 15% for US resident holders who are entitled to claim treaty benefits, subject to compliance with applicable limitation-on-benefits provisions.
(c) Qualified Intermediary Analysis. An analysis of the status and obligations of Meridian Trust Company, N.A., as depositary bank, in its capacity as a Qualified Intermediary for purposes of withholding on distributions to ADS holders.
V&K's tax professionals are invited to participate in the tax due diligence sessions to the extent relevant to the Underwriters' due diligence defense and to the review of tax-related disclosure in the prospectus.
B. Intellectual Property and Technology
We propose a specialist intellectual property and technology review session to be conducted with Dr. Marcus Helder, the Company's Chief Technology Officer, and members of the Company's internal IP team. This session will address the Company's patent portfolio, freedom-to-operate analyses, IP prosecution strategy, IP litigation history, and the commercial significance of the Company's proprietary SiC and GaN technologies. V&K will have full access to the patent portfolio summary, freedom-to-operate analyses, and IP litigation history maintained in the Data Room. The IP specialist session is currently targeted for the week of February 24–26, 2026.
C. Regulatory and Export Controls
Given the heightened regulatory environment applicable to the semiconductor industry, we propose a joint session focused on the Company's compliance with semiconductor export control regulations, including the US Export Administration Regulations (EAR), the International Traffic in Arms Regulations (ITAR), and EU dual-use export control regulations. This session will also address OFAC sanctions compliance and will give particular attention to the operations, customer base, and compliance posture of Halcyon Shanghai Semiconductor Co., Ltd. in the People's Republic of China. Both C&H and V&K will participate in this session, and German counsel will be involved with respect to EU-side regulatory issues. This session is currently targeted for the week of March 3–5, 2026.
D. Environmental. We will conduct a focused review of environmental permits and compliance records for all fabrication and assembly facilities operated by the Company and its subsidiaries, with particular emphasis on the Dresden Fab 3 facility (currently under construction) and chemical handling and waste disposal practices in semiconductor fabrication processes. Given the significance of the Company's manufacturing operations, we will consider whether a site visit to the Dresden facilities (operated by Halcyon Power Solutions GmbH, located at Königsbrücker Straße 180, 01099 Dresden, Germany) is warranted, and we would welcome V&K's view on whether to include such a visit in the due diligence plan.
V. Third-Party Due Diligence
In addition to the document review, management interviews, and specialist sessions described above, the following third-party due diligence activities will be conducted:
Background Checks. Background checks will be conducted on all directors and senior officers of the Company, including Dr. Friedrich Wendt (CEO), Katarina Dalmqvist (CFO), Dr. Marcus Helder (CTO), Ingrid Baumann (COO), Wilhelm Ostermann (General Counsel), and Prof. Dr. Anneliese Voss (Chair of the Supervisory Board), as well as the principals of the selling shareholders, namely Margarethe Wendt (Managing Director of Rheintal Industrieholding GmbH) and Henrik Sørensen (Managing Partner of Kestrel Capital Partners AG). These background checks will encompass public records searches, litigation history, regulatory actions, and bankruptcy filings in all relevant jurisdictions. The results will be coordinated with V&K for purposes of the FINRA filing and the information required in connection with the Underwriters' obligations under FINRA Rule 5110.
Lien and Judgment Searches. Lien and judgment searches will be conducted on Halcyon and each of its material subsidiaries in all relevant jurisdictions, including UCC searches in Delaware and California (for Halcyon Semiconductor USA Inc.), and equivalent searches in Germany, Singapore, the PRC, and the Czech Republic, to the extent available and customary.
Verification of Existing Listing Status. We will independently verify Halcyon's existing listing status on the Frankfurt Stock Exchange (Frankfurter Wertpapierbörse) in the Prime Standard segment of the Regulated Market (Regulierter Markt), where the Company's ordinary shares are currently admitted to trading under the ticker symbol "HCY" (FRA: HCY).
Confirmation of Identifiers. We will confirm the Company's Legal Entity Identifier (LEI: 5299007KBTVZ3XQHGL48) and the Employer Identification Number (EIN: 84-3927561) assigned to Halcyon Semiconductor USA Inc.
VI. Section 11 and Section 12(a)(2) Defense Memorandum Framework
A. Legal Standard
As both of our firms are well aware, the due diligence investigation described in this Protocol is undertaken with a view toward establishing and preserving the Underwriters' defense under Section 11(b)(3) of the Securities Act. Under that provision, an underwriter may avoid liability for material misstatements or omissions in a registration statement by demonstrating that, after reasonable investigation, such underwriter had reasonable ground to believe, and did believe, at the time the registration statement became effective, that the statements contained therein were true and that there was no omission of a material fact required to be stated therein or necessary to make the statements therein not misleading.
The standard of reasonableness applicable to the due diligence defense is that required of a prudent person in the management of his own property. This standard is deliberately flexible, recognizing that the scope and depth of the investigation required will vary depending on the circumstances of the particular offering, including the nature and complexity of the issuer's business, the magnitude of the offering, and the materiality of the information at issue.
It is important to note the distinction between "expertised" portions and "non-expertised" portions of the Registration Statement. The "expertised" portions consist of those portions of the Registration Statement that purport to be made on the authority of an expert, principally the audited financial statements and the auditor's report thereon. With respect to these portions, the underwriter's defense requires only that the underwriter had no reasonable ground to believe, and did not believe, that such statements were untrue or that material facts were omitted — a "reliance" standard that does not require independent investigation. With respect to all other portions of the Registration Statement and prospectus (the "non-expertised" portions), including the business description, risk factors, management's discussion and analysis, and other narrative disclosure, the underwriter bears the higher burden of demonstrating that it conducted a reasonable investigation and had reasonable ground to believe in the accuracy and completeness of the statements made.
In addition to Section 11 liability, the Underwriters face potential liability under Section 12(a)(2) of the Securities Act, which imposes liability on any person who offers or sells a security by means of a prospectus or oral communication that contains a material misstatement or omission. Section 12(a)(2) provides a defense for sellers who can establish that they did not know, and in the exercise of reasonable care could not have known, of the misstatement or omission. The due diligence investigation described herein is intended to establish the evidentiary foundation for this "reasonable care" defense as well.
We note for the record that the Registration Statement on Form F-1 will cover the offering of a total of 21,400,000 ADSs in the base deal (consisting of 15,000,000 primary ADSs and 6,400,000 secondary ADSs), together with an overallotment option (the "Greenshoe Option") granted to the Underwriters to purchase up to an additional 3,210,000 ADSs (representing 15% of the base deal) from the Company, exercisable for a period of 30 days following pricing. If the Greenshoe Option is exercised in full and assuming an offering price of $42.00 per ADS (the midpoint of the proposed range), the maximum aggregate offering size would be approximately $1,034,812,600.
B. Proposed Structure of the Defense Memorandum
Both C&H and V&K will jointly maintain the Due Diligence Defense Memorandum, which will serve as the comprehensive documentary record of the scope and thoroughness of the due diligence investigation conducted in connection with the Offering. The Defense Memorandum will be a living document that is updated and supplemented throughout the due diligence process from commencement through closing. We propose that the Defense Memorandum be organized into the following sections:
1. Chronology. A detailed timeline of all due diligence activities conducted from the date of C&H's initial engagement by the Company (January 12, 2026) through the closing of the Offering (targeted for July 6, 2026). The chronology will include the dates of all document review sessions, management interviews, accountants' sessions, specialist sessions, and other material due diligence activities, together with a summary of the participants in each activity and the topics addressed.
2. Document Review Log. A comprehensive index of all documents reviewed in the Data Room, organized by category in accordance with the Request List. Each entry will include the document identification number assigned in the Data Room, a brief description of the document, the name of the reviewer(s), the date of review, and notation of any issues flagged for further investigation or disclosure consideration.
3. Management Interview Summaries. Summaries of each management interview session, including the date and location of the interview, the identity of all attendees, the topics covered, key information elicited, and any follow-up items identified during or after the session. These summaries will be prepared based on the detailed interview notes taken by associates from each firm, as described in Section III.C above.
4. Accountants' Session Notes. Records of all meetings and discussions with Blackmere & Whitfield regarding auditing procedures, the scope and results of the audit, significant accounting policies and estimates, comfort letter procedures, and the verification of financial data included in the Registration Statement.
5. Specialist Session Notes. Records of the specialist due diligence sessions described in Section IV above, including the tax due diligence sessions, IP and technology review sessions, regulatory and export control sessions, and environmental review sessions.
6. Third-Party Verification Records. Results of the background checks, lien and judgment searches, verification of the Company's listing status and identifiers, and other third-party due diligence activities described in Section V above.
7. Issue Resolution Log. Documentation of the identification, investigation, and resolution of each material issue identified during the course of the due diligence investigation. For each issue, the log will record the nature of the issue, the steps taken to investigate it, the conclusion reached, and, where applicable, the manner in which the issue was addressed through prospectus disclosure or otherwise resolved.
8. Cross-Reference to Prospectus Disclosure. A detailed mapping of due diligence findings to specific sections of the prospectus disclosure, including the risk factors, business description, management's discussion and analysis of financial condition and results of operations ("MD&A"), related-party transactions, compensation discussion, and other relevant sections. This cross-reference will demonstrate the connection between the due diligence investigation and the disclosure ultimately included in the Registration Statement and prospectus.
C. Allocation of Responsibility
The respective responsibilities of C&H and V&K in connection with the preparation of the Registration Statement and the due diligence investigation are as follows:
C&H, as issuer's US securities counsel, will take primary responsibility for preparing the initial drafts of the Registration Statement on Form F-1 and the prospectus forming part thereof, coordinating with the Company's management team and German counsel (Bähr Stein) on all aspects of drafting. C&H will also coordinate with the Company's financial advisors and auditors on the presentation of financial information and MD&A disclosure.
V&K, as the Underwriters' US counsel, will independently verify the adequacy and completeness of the disclosure in the Registration Statement and prospectus from the perspective of the Underwriters' due diligence defense. V&K will review each draft of the Registration Statement and provide comments reflecting the Underwriters' perspective and V&K's independent assessment of the thoroughness of the due diligence record.
Both firms will contribute to the joint Defense Memorandum. C&H will prepare the initial drafts of the Defense Memorandum sections based on its role as coordinator of the due diligence process, and V&K will review, supplement, and comment on each draft to ensure that the Defense Memorandum accurately reflects the totality of the due diligence investigation from both the issuer's and the Underwriters' perspectives.
At closing, each firm will independently prepare and deliver its own negative assurance (10b-5) letter. C&H, as issuer's US counsel, will deliver a 10b-5 letter addressed to the Underwriters. V&K, as the Underwriters' US counsel, will deliver a separate 10b-5 letter addressed to the Underwriters. The preparation and delivery of these letters are independent obligations of each firm and reflect each firm's independent assessment of the adequacy of the due diligence investigation and the accuracy of the disclosure in the Registration Statement.
In addition, Prumvane Thornton LLP (Dr. Stefan Braun, Partner) will contribute German-law due diligence findings to the Defense Memorandum record, including its analysis of German corporate governance matters, compliance with the Aktiengesetz, and other matters of German law relevant to the Offering.
D. Timing and Updates
We propose the following schedule for the preparation and updating of the Defense Memorandum:
The first substantive draft of the Defense Memorandum, incorporating the results of the initial document review and the initial round of management interviews, will be prepared concurrently with the circulation of the first draft of the Registration Statement on Form F-1, which is targeted for March 9, 2026. An updated draft will be prepared following the all-parties drafting session scheduled for March 23–24, 2026, and a further update will be completed prior to the confidential submission of the Registration Statement to the SEC on April 14, 2026. The Defense Memorandum will be updated on an ongoing basis throughout the SEC comment process (with the first SEC comment letter estimated to be received on or about May 12, 2026, and Amendment No. 1 to the Registration Statement targeted for filing on May 26, 2026) and will be finalized in a closing version as of the closing date of the Offering on July 6, 2026.
VII. Confidentiality and Privilege
All due diligence work product, interview notes, specialist session records, and Defense Memorandum materials prepared by or on behalf of C&H, V&K, or any other counsel participating in the due diligence investigation are prepared in anticipation of potential litigation under the Securities Act and are protected by the attorney-client privilege and the attorney work-product doctrine. The parties shall take all necessary steps to preserve the privileged and confidential nature of these materials.
All materials prepared in connection with the due diligence investigation and the Defense Memorandum shall be prominently marked with the following legend:
"PRIVILEGED AND CONFIDENTIAL — ATTORNEY WORK PRODUCT"
The Defense Memorandum and all related work product shall not be shared with, or disclosed to, any third party other than the Underwriters (Westbridge Securities LLC, Pinnacle Morgan & Co., Inc., Andover Barcliffe Group Inc., and Northpointe Capital LLC) and their respective authorized personnel, without the prior written consent of both C&H and V&K. Any disclosure to any other party — including any regulatory authority, rating agency, or potential investor — must be approved in advance by both firms.
To the extent necessary to preserve the attorney-client privilege and work-product protection over joint due diligence work product shared between issuer's counsel and underwriters' counsel, the parties will enter into a common interest agreement (a "Common Interest Agreement") pursuant to which the parties agree that the sharing of privileged information between them in connection with the Offering does not constitute a waiver of any applicable privilege. We propose to discuss whether the execution of a separate Common Interest Agreement is necessary or advisable, and if so, to finalize such an agreement promptly.
VIII. Coordination with Other Advisors
In the course of the due diligence process, we anticipate coordination with the following additional advisors retained by the Company or the Underwriters:
Ashton & Burke Advisory GmbH (Lukas Frey, Managing Partner, Theatinerstraße 11, 80333 Munich, Germany) — Financial advisor to Halcyon. Ashton & Burke will provide valuation analyses, industry benchmarking, and market context to inform the due diligence sessions as requested by either C&H or V&K.
Bridgeport Investor Relations LLC (Thomas Harding, Senior Vice President, 350 Fifth Avenue, Suite 6820, New York, New York 10118) — US investor relations advisor to Halcyon. Bridgeport's work on investor messaging and positioning will be reviewed to ensure consistency with the prospectus disclosure and to avoid any inconsistencies between the Company's public investor communications and the Registration Statement.
Meridian Trust Company, N.A. (Patricia Novak, Vice President, Depositary Receipts, 101 Barclay Street, New York, New York 10286) — Depositary bank for the ADS program. Due diligence will be conducted on the deposit agreement mechanics, custodian arrangements, the process for issuance and cancellation of ADSs, voting procedures for ADS holders, and the depositary's obligations and rights under the deposit agreement.
Crestfield Transfer Services Inc. (Angela Moretti, Director, Corporate Actions, 6201 15th Avenue, Brooklyn, New York 11219) — Transfer agent and ADS registrar. Operational due diligence will be conducted on Crestfield's systems and procedures for the registration, transfer, and cancellation of ADSs and the maintenance of the ADS register.
Clearwater D&O Insurance Brokers Ltd. (Emma Callister, Vice President, Financial Lines) — Insurance broker for the Company's D&O program. Clearwater will assist in the review of the adequacy of the Company's D&O insurance program in light of the Offering, including the sufficiency of the $75,000,000 total program limits and the structure of the layered program. We note that the estimated annual premium for the current D&O program is approximately $2,800,000, and we will assess whether adjustments to the program are warranted in connection with the Company's transition to a publicly listed company in the United States.
IX. Proposed Due Diligence Calendar (Key Dates)
The following table sets forth the proposed due diligence calendar, incorporating the key dates and milestones discussed above. All dates are subject to adjustment based on the progress of the due diligence investigation, the SEC review process, and market conditions.
X. Contact Information
For purposes of due diligence coordination, the primary contacts at each firm are as follows:
Calderwood & Harkness LLP
Vivienne St. Claire, Responsible Partner
Email: vivienne.stclaire@calderwoodharkness.com
Claire Dempsey, Lead Associate
Email: claire.dempsey@calderwoodharkness.com
Audrey Zhou, Working Associate
Email: audrey.zhou@calderwoodharkness.com
Calderwood & Harkness LLP One Liberty Plaza, 42nd Floor New York, New York 10006 Telephone: (212) 558-4000
Varen & Kessler LLP
Martin Ashford, Partner
Email: mashford@varenkessler.com
Priya Ranganathan, Senior Associate
Email: pranganathan@varenkessler.com
Varen & Kessler LLP 51 West 52nd Street New York, New York 10019
All due diligence-related correspondence, document requests, and scheduling communications should be directed to the contacts listed above. We ask that, to the extent practicable, all communications related to due diligence be made in writing (including by email) so that a complete record of the due diligence process is maintained.
XI. Request for Confirmation
We respectfully request that V&K confirm its agreement to the Protocol and Defense Memorandum framework set forth in this letter, together with any proposed modifications or additions, on or before February 3, 2026. We are available at your convenience to schedule a call or meeting to discuss any points requiring further coordination or clarification.
We recognize that the Protocol described herein represents the parties' initial framework for the conduct of due diligence, and that the scope and sequence of due diligence activities may evolve as the process unfolds and new information comes to light. Accordingly, the Protocol may be amended at any time by mutual written agreement of C&H and V&K.
We look forward to working with you and your team throughout this process.
Very truly yours,
CALDERWOOD & HARKNESS LLP
By: ________
Vivienne St. Claire Partner
cc (via email):
Robert Adeyemi, Partner, Calderwood & Harkness LLP Claire Dempsey, Associate, Calderwood & Harkness LLP Audrey Zhou, Associate, Calderwood & Harkness LLP Leonard Cross, Partner, Calderwood & Harkness LLP Wilhelm Ostermann, General Counsel, Halcyon Semiconductor AG Dr. Christoph Maurelban, Partner, Bähr Stein Rechtsanwälte PartGmbB Dr. Stefan Braun, Partner, Prumvane Thornton LLP Jonathan Hartwell, Managing Director, Westbridge Securities LLC
This letter and all attachments hereto are privileged and confidential and are prepared in anticipation of litigation. This letter constitutes attorney work product and is protected by the attorney-client privilege and the work-product doctrine. Any unauthorized review, use, disclosure, or distribution is prohibited.
Metric | FY2023 | FY2024 | FY2025 (Unaudited)
Revenue | €3,214M | €3,508M | €3,820M
EBITDA | €869M | €966M | €1,069M
EBITDA Margin | 27.0% | 27.5% | 28.0%
Net Income | €482M | €541M | €612M
Total Assets | — | — | €7,450M
Total Debt | — | — | €890M
Cash and Cash Equivalents | — | — | €740M
Capital Expenditures | — | — | €820M
Milestone | Target Date
Initial draft of Defense Memorandum outline | February 28, 2026
First substantive draft (incorporating document review and initial interview notes) | March 9, 2026
Updated draft following all-parties drafting session | March 23–24, 2026
Pre-filing update | April 14, 2026
Ongoing updates through SEC comment process | May–June 2026
Amendment No. 1 update | May 26, 2026
Public filing update | June 8, 2026
Final update and closing version | July 6, 2026
Activity | Target Date
Due diligence commencement / Data Room access | January 27, 2026
First management interview round | February 3–14, 2026
Initial accountants' session (Blackmere & Whitfield) | February 10–12, 2026
Tax due diligence session (Leonard Cross, C&H) | February 17–19, 2026
IP / technology specialist session | February 24–26, 2026
Defense Memorandum outline draft | February 28, 2026
Regulatory / export controls session | March 3–5, 2026
First draft F-1 circulation | March 9, 2026
All-parties drafting session | March 23–24, 2026
Pre-filing management bring-down interview | April 7–9, 2026
Confidential submission to SEC | April 14, 2026
SEC first comment letter (estimated) | May 12, 2026
Amendment No. 1 filing | May 26, 2026
Public filing of Registration Statement | June 8, 2026
Pre-pricing management bring-down interview | June 16–18, 2026
SEC declaration of effectiveness (target) | June 22, 2026
Roadshow launch | June 23, 2026
Pricing | July 1, 2026
Closing bring-down interview | July 3, 2026
Closing / Settlement (T+2) | July 6, 2026

PRIVILEGED AND CONFIDENTIAL — ATTORNEY WORK PRODUCT

VIA EMAIL AND OVERNIGHT COURIER

CALDERWOOD & HARKNESS LLP

Record

Parties

Dates

Amounts