SEC Form 424B5 filed by SEALSQ Corp

Filed Pursuant to Rule

424(b)(5) Registration

Number 333-286098

PROSPECTUS SUPPLEMENT

(To Prospectus dated April 2, 2025)

SEALSQ Corp

Up to $100,000,000 of Ordinary Shares

We have entered into a Controlled Equity Offering^SM Sales Agreement (the “Sales Agreement”) with Cantor Fitzgerald & Co. (“Cantor”) and Maxim Group LLC (“Maxim”) (each, a “Sales Agent” and together, the “Sales Agents”), dated May 19, 2025, relating to the sale of our Ordinary Shares, par value US$0.01 per share (our “Ordinary Shares”), offered by this prospectus supplement and the accompanying prospectus. In accordance with the terms of the Sales Agreement, we may offer and sell our Ordinary Shares having an aggregate offering price of up to $100,000,000 from time to time through or to Cantor, acting as the sole designated sales agent and/or principal.

Sales of our Ordinary Shares, if any, under this prospectus supplement and the accompanying prospectus will be made by any method that is deemed an “at the market offering” as defined in Rule 415 promulgated under the Securities Act of 1933, as amended (the “Securities Act”). Cantor is not required to sell any specific number or amount of our Ordinary Shares but will act as our sales agent using commercially reasonable efforts, consistent with its normal trading and sales practices on mutually agreed terms between Cantor and us. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

We will pay the Sales Agents a commission, in cash, at a rate of 3.0% of the gross sales price per share sold through the Sales Agreement. In connection with the sale of the Ordinary Shares on our behalf, each Sales Agent will be deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation paid to either Sales Agent will be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification and contribution to each Sales Agent with respect to certain liabilities, including liabilities under the Securities Act. We have also agreed to reimburse certain of the Sales Agents’ expenses in connection with the offering as further described in the “Plan of Distribution” section beginning on page S-14 of this prospectus supplement.

Our Ordinary Shares are listed on Nasdaq Capital Market under the symbol “LAES.” The last reported sale price of our Ordinary Shares on the Nasdaq Capital Market on May 16, 2025 was $2.58 per share.

Investing in our Ordinary Shares involves a high degree of risk and uncertainty. See “Risk Factors” beginning on page S-8 of this prospectus supplement, on page 4 of the accompanying base prospectus and in the documents incorporated by reference into this prospectus supplement and accompanying base prospectus concerning factors you should consider before investing in our Ordinary Shares.

We are an “emerging growth company” and a “foreign private issuer” under applicable federal securities laws and are subject to reduced public company reporting requirements.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Cantor

Maxim Group LLC

The date of this prospectus supplement is May 19, 2025.

TABLE OF CONTENTS

PROSPECTUS SUPPLEMENT

Page

PROSPECTUS

Page

ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement and the accompanying base prospectus are part of a registration statement on Form F-3 (Registration No. 333-286098) that we filed with the United States Securities and Exchange Commission (“SEC”) using a “shelf” registration process. Under this “shelf” registration process, we may, from time to time, sell our Ordinary Shares having an aggregate offering price of up to $100,000,000 pursuant to this prospectus supplement and the accompanying prospectus at prices and on terms to be determined by market conditions at the time of the offering. The accompanying base prospectus provides you with a general description of us and the securities we may offer, some of which do not apply to this offering. Each time we sell securities, we provide a prospectus supplement that contains specific information about the terms of that offering. A prospectus supplement may also add, update or change information contained in the accompanying base prospectus.

This prospectus supplement relates to the offering of our Ordinary Shares. To the extent there is a conflict between the information contained in this prospectus supplement and the accompanying base prospectus, you should rely on the information in this prospectus supplement. This prospectus supplement, the accompanying base prospectus, and the documents we incorporate by reference herein and therein include important information about us and our Ordinary Shares and other information you should know before investing. You should read both this prospectus supplement and the accompanying base prospectus, together with the additional information described below under the heading “Where You Can Find Additional Information.” This prospectus supplement contains summaries of certain provisions contained in some of the documents described in this prospectus supplement, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to in this prospectus supplement have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus supplement is a part, and you may obtain copies of those documents as described under “Where You Can Find Additional Information.”

You should rely only on the information contained in or incorporated by reference in this prospectus supplement or the accompanying base prospectus. We have not authorized anyone to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. We are not making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted or in which the person making that offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation. You should assume that the information appearing in this prospectus supplement, the accompanying base prospectus, and the documents incorporated by reference herein and therein is accurate only as of the date of those respective documents. Our business, financial condition, results of operations and prospects may have changed since those dates. You should carefully read this entire prospectus supplement and the accompanying base prospectus, including the information included and referred to under “Risk Factors” below, the information incorporated by reference in this prospectus supplement and in the accompanying base prospectus, and the financial statements and the other information incorporated by reference in the accompanying base prospectus, before making an investment decision.

We prepare our financial statements in United States dollars and in accordance with United States generally accepted accounting principles.

All references in this prospectus to “$,” “US$,” “U.S. Dollars” and “dollars” are to United States dollars.

Unless otherwise indicated, references to “SEALSQ,” the “Company,” “we,” “our,” “us” or similar terms refer to the registrant, SEALSQ Corp, and its subsidiaries, except where the context otherwise requires.

This prospectus supplement and the information incorporated by reference herein and therein include trademarks, service marks and trade names owned by us or other companies. Solely for convenience, trademarks referred to in this prospectus supplement, including logos, artwork and other visual displays, may appear without the ® or ™ symbols. We do not intend our use or display of other companies’ trade names or trademarks to imply a relationship with, or endorsement or sponsorship of us by, any other companies. All trademarks, service marks and trade names included or incorporated by reference into this prospectus supplement are the property of their respective owners.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement, the accompanying prospectus and the information incorporated by reference herein contain forward-looking statements. These forward-looking statements include information about possible or assumed future results of our operations or our performance. Words such as “expects,” “intends,” “plans,” “believes,” “anticipates,” “estimates,” “projects,” “forecasts” and variations of such words and similar expressions, as they relate to us, WISeKey International Holding S.A., our parent company (“WISeKey”), our management or third parties, are intended to identify the forward-looking statements. Forward-looking statements include statements regarding our business strategy, financial performance, results of operations, market data, events or developments that SEALSQ expects or anticipates will occur in the future, as well as any other statements which are not historical facts. Although we believe that the expectations reflected in such forward-looking statements are reasonable, no assurance can be given that such expectations will prove to have been correct. These statements are based on information available as of the date of this prospectus supplement, involve known and unknown risks, and are based upon a number of assumptions and estimates that are inherently subject to significant uncertainties and contingencies, many of which are beyond our control. Actual results may differ materially from those expressed or implied by such forward-looking statements. Forward-looking statements include, but are not limited to, statements we make regarding:

These forward-looking statements include, but are not limited to, statements relating to:

        The preceding list is not intended to be an exhaustive list of all of our forward-looking statements. The forward-looking statements are based on our beliefs, assumptions and expectations of future performance, taking into account the information currently available to us and are only predictions based upon our current expectations and projections about future events. There are important factors that could cause our actual results, levels of activity, performance or achievements to differ materially from the results, levels of activity, performance or achievements expressed or implied by these forward-looking statements. Those factors include, in addition to those set forth in Item 3.D. Risk Factors of our 2024 Annual Report on Form 20-F and those included elsewhere in this report, among others, the following:

Given these risks and uncertainties, you should not place undue reliance on forward-looking statements as a prediction of actual results.

WE UNDERTAKE NO OBLIGATION TO PUBLICLY UPDATE OR REVISE ANY FORWARD-LOOKING STATEMENTS CONTAINED IN THIS PROSPECTUS SUPPLEMENT OR THE BASE PROSPECTUS OR THE DOCUMENTS TO WHICH WE REFER YOU IN THIS PROSPECTUS SUPPLEMENT OR THE BASE PROSPECTUS, TO REFLECT ANY CHANGE IN OUR EXPECTATIONS WITH RESPECT TO SUCH STATEMENTS OR ANY CHANGE IN EVENTS, CONDITIONS OR CIRCUMSTANCES ON WHICH ANY STATEMENT IS BASED, EXCEPT AS REQUIRED BY LAW.

PROSPECTUS SUPPLEMENT SUMMARY

This summary contains basic information about us and our business but does not contain all of the information that is important to your investment decision. Before making an investment decision, you should carefully read this summary together with the more detailed information contained elsewhere in this prospectus supplement and the accompanying base prospectus and the documents incorporated herein and therein by reference, including our Annual Report on Form 20-F for the fiscal year ended December 31, 2024 (the “Annual Report”). Investors should carefully consider the information set forth under the caption “Risk Factors” appearing elsewhere in this prospectus supplement, including those described in documents incorporated by reference herein.

About Our Company

This summary highlights selected information contained elsewhere in this prospectus supplement that we consider important. This summary does not contain all of the information you should consider before investing in our securities. You should read this summary together with the entire prospectus supplement and accompanying base prospectus, including the risks related to our business, our industry and investing in our securities that we describe under “Risk Factors,” and our consolidated financial statements and the related notes incorporated by reference in this prospectus supplement before making an investment in our securities.

SEALSQ is a leading innovator in Post-Quantum Technology hardware and software solutions. Our technology seamlessly integrates Semiconductors, Public Key Infrastructure (“PKI”), and Provisioning Services, with a strategic emphasis on developing state-of-the-art Quantum Resistant Cryptography and Semiconductors designed to address the urgent security challenges posed by quantum computing. Our products are engineered to safeguard critical systems, enhancing resilience and security across diverse industries.

SEALSQ was established as a subsidiary of WISeKey International Holding AG, combining decades of expertise in cryptographic security and trusted digital infrastructure. Headquartered in Switzerland, we operate across Europe, the United States, and other strategic markets. Our solutions provide the foundation of digital trust for businesses and governments worldwide.

SEALSQ’s comprehensive portfolio, which includes secure microcontrollers, PKI services, compliance with IoT standards like Matter, GSMA eUICC root certificates, tailored ASICs, and post-quantum cryptography capabilities, uniquely positions the Company to address evolving market needs. These capabilities, combined with SEALSQ’s entry into the Trust Platform Module (“TPM”) market, ensure strong growth potential and market leadership in the cybersecurity and IoT sectors.

SEALSQ delivers integrated digital security solutions that combine four critical components into a unified offering: Root- of-Trust, Secure Chips, trusted Identity Generation and Management (PKI), and Personalization Services. Together, these components ensure the confidentiality, integrity, and authenticity of connected devices and digital communications.

Our offerings are structured around four foundational technology pillars:

SEALSQ’s comprehensive product range meets the growing demand for secure, certified solutions across industries:

SEALSQ solutions serve high-growth industries requiring secure, scalable, and certified solutions. Some examples of the use cases of our products are as follows:

SEALSQ semiconductors and PKI services contribute to secure millions of objects: luxury products, routers, gateways, utilities meters, E.V. chargers, drones, authentication dongles, storage memory USB sticks, medical devices, connected door-locks, and a variety of other electronic consumers devices.

Implications of Being an Emerging Growth Company and a Foreign Private Issuer

Emerging Growth Company

We are an “emerging growth company”, as defined in the JOBS Act, and we may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. We cannot predict if investors will find our Ordinary Shares less attractive because we may rely on these exemptions. If some investors find our Ordinary Shares less attractive as a result, there may be a less active trading market for our Ordinary Shares and our share price may be more volatile.

In addition, under the JOBS Act, our independent registered public accounting firm will not be required to attest to the effectiveness of our internal control over financial reporting pursuant to Section 404 of the Sarbanes-Oxley Act of 2002 for so long as we are an emerging growth company.

For as long as we take advantage of the reduced reporting obligations, the information that we provide our shareholders may be different from information provided by other public companies.

Foreign Private Issuer

As a foreign private issuer, we are permitted to, and we do, rely on exemptions from certain Nasdaq corporate governance standards applicable to domestic U.S. issuers. This may afford less protection to holders of our Ordinary Shares.

We are exempted from certain corporate governance requirements of Nasdaq by virtue of being a foreign private issuer. We are required to provide a brief description of the significant differences between our corporate governance practices and the Nasdaq corporate governance practices required to be followed by domestic U.S. companies listed on Nasdaq. The standards applicable to us are considerably different from the standards applied to domestic U.S. issuers. For instance, we are not required to:

We have relied on and intend to continue to rely on some of these exemptions. As a result, you may not be provided with the benefits of certain corporate governance requirements of Nasdaq.

Because we qualify as a foreign private issuer under the Exchange Act, we are also exempt from certain provisions of the securities rules and regulations in the United States that are applicable to U.S. domestic issuers, including:

Recent Developments

May 6, 2025 Registered Direct Offering

Securities Purchase Agreement

On May 5, 2025, we entered into a securities purchase agreement (the “SPA”) with several institutional investors named therein (the “Investors”), pursuant to which we agreed to sell and issue 10,000,000 Ordinary Shares to the Investors at a purchase price of US$2.00 per Ordinary Share, in a registered direct offering (the “Offering”). The closing of such registered direct offering occurred on May 6, 2024 (the “Closing Date”).

The gross proceeds to the Company from the Offering were approximately $20,000,000.00, before deducting the placement agent’s fees and other estimated offering expenses payable by the Company.

The Offering was made pursuant to the Company’s existing shelf registration statement on Form F-3 (File No. 333- 286098), which was declared effective on April 2, 2025 by the U.S. Securities and Exchange Commission (the “Registration Statement”). A prospectus supplement to the Registration Statement for the Offering was filed with the Commission on May 6, 2025.

Pursuant to the terms of the SPA, the Company has agreed that until the date that is sixty (60) days after the Closing Date, we may not issue, enter into any agreement to issue or announce the issuance or proposed issuance of any Ordinary Shares or Ordinary Share equivalents, effect or enter into an agreement to effect any issuance of Ordinary Shares or Ordinary Share equivalents, or, file any registration statement or any amendment or supplement thereto, in each case, subject to certain exceptions, without the prior consent of the Investors. The preceding sentence shall not apply to the issuance of, or registration statements with respect to (a) Ordinary Shares or options issued pursuant to any stock option plan, and (b) following the date which is ten (10) days after the Closing Date, the entering into an agreement and the making of applicable filings with respect to an at-the-market offering facility (the “ATM Facility”) provided, however, that (x) during the period beginning on date which is ten (10) days after the date of the initial launch date of date of the ATM Facility and ending on the date which is forty five (45) days after the initial launch date of the ATM Facility, the Company may sell Ordinary Shares pursuant to the ATM Facility for a purchase price that is equal to or greater than $2.52 per Ordinary Share, and (y) during the period beginning on date which is forty six (46) days after the date of the initial launch date of date of ATM Facility and ending on the date which is sixty (60) days after the initial launch date of the ATM Facility, the Company may sell Ordinary Shares pursuant to the ATM Facility for a purchase price that is equal to or greater than $2.31 per Ordinary Share.

In addition, we agreed not to issue, or enter into any agreement to issue, any Ordinary Shares of the Company or “Ordinary Share Equivalents” involving a “Variable Rate Transaction” (each as defined in the SPA), provided, however, that notwithstanding the foregoing, the Company may enter into the ATM Facility at any time following the date which is ten (10) days after the Closing Date and, subject to the restrictions set forth in the paragraph above, may sell Ordinary Shares pursuant to the ATM Facility.

Further, the Company has agreed that until the date that is the twenty four (24) month anniversary of the execution date of the SPA, upon any issuance by the Company or any of its subsidiaries of Ordinary Shares or securities exercisable for or convertible into Ordinary Shares for cash consideration, indebtedness or a combination of units thereof (a “Subsequent Financing”), the investors have the right to participate (on a pro rata basis based upon the number of Ordinary Shares purchased by each Purchaser pursuant to the SPA) in up to an amount of the Subsequent Financing equal to 30% of the Subsequent Financing (the “Participation Maximum”) on the same terms, conditions and price provided for in the Subsequent Financing. This participation right shall not apply in respect of certain issuances pursuant to the Company’s stock option plan, any business acquisition (excluding any such transaction entered into primarily to raise capital), or the ATM Facility.

Placement Agency Agreement

On May 5, 2025, the Company entered into an agency agreement (the “PAA”) with Maxim Group LLC (the “Placement Agent”), pursuant to which the Company agreed to pay the Placement Agent an aggregate fee equal to 7.0% of the aggregate gross proceeds received by the Company from the sale of the Ordinary Shares in the Offering. The Company also agreed to reimburse the Placement Agent for up to $40,000 in accountable expenses, including the Placement Agent’s legal counsel’s fees. 

Lock-Up Agreements

Our parent company, WISeKey International Holding AG (“WISeKey”), and certain of our officers have agreed, subject to certain exceptions, not to offer, issue, sell, contract to sell, encumber, grant any option for the sale of or otherwise dispose of any of our Ordinary Shares or other securities convertible into or exercisable or exchangeable for our Ordinary Shares for a period of 60 days after the Closing Date without the prior written consent of the Placement Agent.

Maxim Right of First Refusal

Pursuant to an engagement letter dated December 11, 2024 with Maxim Group LLC (“Maxim”), until December 17, 2025 (the “End Date”), Maxim has the (i) right of first refusal to act as the sole book runner and sole placement agent for any and all of our private equity, equity- linked or debt (excluding commercial bank debt and at-the-market offerings) offerings (including any registered direct offerings); and (ii) right of participation for any of our registered public offerings (excluding registered direct offerings) to act as underwriter and co-book runner with a minimum of forty percent (40%) economics. Further, prior to the End Date, if we complete any financing of equity, equity-linked, convertible or debt or other capital raising activity with, or receive any proceeds from, any of the investors contacted or introduced to us by Maxim, then we will, upon the closing of such financing or receipt of such proceeds, be obligated to pay Maxim seven percent (7%) of the aggregate gross proceeds.

PERTE CHIP

WISeKey and SEALSQ jointly, together with OdinS and TProtege, two Spanish companies with extensive experience in R&D&i (Research & Development & Innovation) worldwide and in the design and manufacturing of IoT devices and solutions, plan to establish in the Region of Murcia a “Center of Excellence in Cybersecurity and Microchips” under the financial umbrella of the Microelectronics and Semiconductors Plan (PERTE CHIP) initiated by Spain.

The project called Quantix Edges is in the final stages of the approval process by the Sociedad Espanola para la Transformacion Tecnologica (SETT), the Spanish government’s entity responsible for funding under the PERTE budgets. The project features a EUR 20 million investment by WISeKey, SEALSQ, OdinS and TProtege and SETT over a period of 3 years, involving the creation of up to 200 highly qualified direct jobs (300 indirect).

IC’ALPS

On February 27, 2025, the Company announced that it has entered into exclusive negotiations with the shareholders of IC’ALPS SAS (“IC’ALPS”), an ASIC design and supply specialist based in Grenoble, France, to acquire 100% of the share capital and voting rights of IC’ALPS. These exclusive negotiations result from the execution of a Letter of Intent with IC’ALPS and its shareholders. The acquisition is subject to, amongst other items, the completion of the appropriate due diligence, execution of definitive agreements, and authorization by French regulatory authorities. This strategic acquisition would reinforce SEALSQ’s commitment to advancing its Application-Specific Integrated Circuit (ASIC) development to meet the growing demand in the sector and add approximately 100 highly-skilled staff based out of IC’ALPS’ current centers in Grenoble and Toulouse, France.

Corporate Information

SEALSQ Corp is a BVI business company incorporated and existing under the laws of the British Virgin Islands. Our registered office in the British Virgin Islands is at Craigmuir Chambers, Road Town, Tortola, VG 1110, British Virgin Islands. Our principal executive offices and effective place of management are located at Avenue Louis-Casaï 58, 1216 Cointrin, Switzerland. Our telephone number from the United States is 011 41 22 594 3000. Our website can be accessed at www.SEALSQ.com. The information on or linked to on our website is not a part of this prospectus supplement.

THE OFFERING

The following summary contains basic information about the offering and is not intended to be complete. It does not contain all the information that is important to you. You should carefully read the entire prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein before making an investment decision.

The number of Ordinary Shares to be outstanding after this offering is based on 114,508,901 Ordinary Shares outstanding as of May 5, 2024, and exclude, as of that date, the following number of shares outstanding:

RISK FACTORS

An investment in our Ordinary Shares involves a high degree of risk. Before investing in our Ordinary Shares, you should carefully consider the risk factors set forth below and those described under “Risk Factors” in the documents incorporated by reference herein, including in our most recent Annual Report on Form 20-F filed with the SEC, together with the other information included in this prospectus supplement, the base prospectus and incorporated by reference herein from our filings with the SEC. If any of such risks or uncertainties occurs, our business, financial condition, and operating results could be materially and adversely affected. Additional risks and uncertainties not currently known to us or that we currently deem immaterial also may materially and adversely affect our business operations. As a result, the trading price of our Ordinary Shares could decline and you could lose all or a part of your investment.

Risks Related to this Offering

Our management will have broad discretion over the use of the net proceeds from this offering, and you may not agree with how we use the proceeds and the proceeds may not be invested successfully.

Our management will have broad discretion as to the use of the net proceeds from this offering and could use them for purposes other than those contemplated at the time of this offering. Accordingly, you are relying on the judgment of our management with regard to the use of these net proceeds, and you will not have the opportunity, as part of your investment decision, to assess whether the proceeds will be used appropriately. We intend to use the proceeds from this offering in the manner described under “Use of Proceeds.” It is possible that the proceeds will be invested in a way that does not yield a favorable, or any, return for SEALSQ.

Purchasers may experience immediate dilution in the book value per ordinary share of the ordinary shares purchased in the offering.

The Ordinary Shares sold in this offering, if any, will be sold from time to time at various prices. After giving effect to the issuance of 4,469,382 Ordinary Shares following the exercise of warrants to purchase 4,469,382 Ordinary Shares at a price of $1.70 per share on January 3, 2025, our pro forma net tangible book value as of December 31, 2024 would have been approximately $85.2 million or $0.82 per Ordinary Share.

After giving further effect to the sale of 10,000,000 Ordinary Shares at a price of $2.00 per share on May 6, 2025, and after deducting estimated aggregate offering expenses payable by us, our pro forma, as adjusted net tangible book value as of December 31, 2024 would have been approximately $103.6 million, or $0.90 per Ordinary Share.

We expect that the offering price of our Ordinary Shares will be substantially higher than the net tangible book value per Ordinary Share, and per each underlying Ordinary Share, prior to this offering. After giving effect to the sale of Ordinary Shares in the aggregate amount of $100 million at an assumed offering price of $2.58 per Ordinary Share, the last reported sale price of our Ordinary Shares on May 16, 2025 on Nasdaq, and after deducting commissions and estimated offering expenses, our as adjusted net tangible book value as of December 31, 2024 would have been $200.3 million, or $1.31 per Ordinary Share. This represents an immediate increase in net tangible book value of approximately $0.41 per Ordinary Share to our existing shareholders and an immediate dilution in as adjusted net tangible book value of $1.27 per Ordinary Share to purchasers in this offering.

You may experience future dilution as a result of future equity offerings.

In order to raise additional capital, we may in the future offer additional of our Ordinary Shares or other securities convertible into or exchangeable for our Ordinary Shares. We cannot assure you that we will be able to sell Ordinary Shares or other securities in any other offering at a price per Ordinary Share that is equal to or greater than the price per Ordinary Share paid by investors in this offering, and investors purchasing Ordinary Shares or other securities in the future could have rights superior to existing shareholders. The price per Ordinary Share at which we sell additional Ordinary Shares or other securities convertible into or exchangeable for our Ordinary Shares in future transactions may be higher or lower than the price per Ordinary Share in this offering. In addition, the market price of our Ordinary Share could fall as a result of resales of any of these Ordinary Shares due to an increased number of Ordinary Shares available for sale in the market.

The actual number of shares we will issue under the Sales Agreement, at any one time or in total, is uncertain.

Subject to certain limitations in the Sales Agreement and compliance with applicable law, we have the discretion to deliver a placement notice to Cantor at any time throughout the term of the Sales Agreement. The number of shares that are sold by Cantor after delivering a placement notice will fluctuate based on the market price of our Ordinary Shares during the sales period and limits we set with Cantor. Because the price per share of each share sold will fluctuate based on the market price of our Ordinary Shares during the sales period, it is not possible at this stage to predict the number of shares that will be ultimately issued.

The Ordinary Shares offered hereby will be sold in “at the market offerings” and investors who buy shares at different times will likely pay different prices.

Investors who purchase shares in this offering at different times will likely pay different prices, and accordingly may experience different levels of dilution and different outcomes in their investment results. We will have discretion, subject to market demand, to vary the timing, prices and number of shares sold in this offering. In addition, subject to the final determination by our board of directors or any restrictions we may place in any applicable placement notice, there is no minimum or maximum sales price for shares to be sold in this offering. Investors may experience a decline in the value of the shares they purchase in this offering as a result of sales made at prices lower than the prices they paid.

General Risks

Our business could suffer as a result of tariffs and trade sanctions or similar actions. 

The imposition by the U.S. government of trade measures, including tariffs, sanctions or other restrictions on goods exported from, or imported into, the United States, or countermeasures imposed in response to such U.S. government trade measures, could adversely affect global economic conditions, our operations or our ability to sell our products globally, which could adversely affect our operating results and financial condition. Recently, the U.S. government has initiated the imposition of stronger trade measures on certain goods exported from, or imported into, the U.S., and reciprocally non-U.S. governments have increased their threat and implementation of countermeasures. For example, recently, the U.S government announced proposed tariffs on imports of semiconductor chips into the U.S. The U.S. President has increased, and reserved for further increases in, the scope and amount of tariffs in the event of retaliatory countermeasures, and the future of existing tariffs and, as a result, the possibility for new tariffs and countermeasures, remains very uncertain. A large amount of our current supply chain does not directly import products to the U.S. as we supply to contract manufacturers located outside the U.S. This is the case even when our ultimate customer is a U.S. company. However, the tariffs on imports of semiconductor chips, or products containing semiconductor chips, into the U.S. could impact upon the contract manufacturers, and the entire semiconductor supply chain, when the finished goods are delivered to the end-customer. Furthermore, end-customers may seek to restructure the supply chain to areas or countries unaffected by tariffs, or demand for the semiconductor supply chain to absorb the added costs of the tariffs and that will, in turn, reduce our revenue and gross profit. There is a further possibility that any future tariffs may still impact upon our ability to sell our product and to remain competitive in the market. Escalations in trade measures may directly impair our business by increasing trade-related costs or disrupting established supply chains and may indirectly impair our business by causing a negative effect on global economic conditions and financial markets. In addition, de-escalation of trade measures, or selected exemptions from trade measures, may not result in an immediate increase in our business activity. The ultimate impact of the evolving trade measures is uncertain and may be affected by various factors, including whether and when such trade measures are implemented, the timing when such measures may become effective, and the amount, scope, or nature of such trade measures.

Additional changes or threatened changes in U.S. trade measures have affected and may continue to affect trade involving many countries as well, including Mexico, Canada, Colombia, Taiwan, the People’s Republic of China, the United Kingdom, and the member countries of the European Union. Each of these measures or threatened measures may instigate reciprocal countermeasures by affected countries, potentially accelerating further increases in trade measures. Any trade measure against Taiwan may specifically target imports of semiconductor products, which, if imposed, could seriously and negatively affect our business and the U.S. economy overall. The materials subject to these trade measures may impact the cost or availability of raw materials used by our suppliers or in our customers’ products. We cannot predict the evolving trade policies, but the imposition of trade measures by the U.S. on a broader range of imports, or further retaliatory trade measures taken in response to additional U.S. trade measures, could increase costs in our supply chain or reduce demand of our customers’ products, either of which could adversely affect our results of operations. Any increase in trade-related costs associated with such measures may impair the profitability of such international production, may strain our suppliers’ ability to reliably provide inputs necessary to produce these items, and may otherwise affect our partners’ abilities to provide our products at previously contracted prices. Our business and financial results could be negatively affected as a result.

USE OF PROCEEDS

The amount of net proceeds from this offering will depend upon the number of our Ordinary Shares sold and the market prices at which they are sold. Because there is no minimum offering amount required as a condition of this offering, the actual total public offering amount, commissions and net proceeds to us, if any, are not determinable at this time. There can be no assurance that we will be able to sell any of our Ordinary Shares under or fully utilize the Sales Agreement as a source of financing.

We intend to use the net proceeds from the sale of our Ordinary Shares offered by us under this prospectus supplement for general corporate purposes. General corporate purposes may include funding the deployment of its next-generation post-quantum semiconductor technology and ASIC capabilities in the United States, to support working capital, additions to working capital, financing of capital expenditures, repayment or redemption of existing indebtedness, repurchases of stock and future acquisitions and strategic investment opportunities.

The amount, timing and nature of specific expenditures of net proceeds from this offering will depend on a number of factors, including the timing, scope, progress and results of our development efforts and the timing and progress of any collaboration efforts. As of the date of this prospectus supplement, we cannot specify with certainty all of the particular uses of the proceeds from this offering. Accordingly, we will retain broad discretion over the use of such proceeds.

CAPITALIZATION

The following table presents our total capitalization and cash and cash equivalents as of December 31, 2024,

The information set forth in the following table should be read in conjunction with, and is qualified in its entirety by, reference to our financial statements and the notes thereto incorporated by reference into this prospectus supplement and the accompanying prospectus.

______________________

CERTAIN TAX CONSIDERATIONS

You should carefully read the discussion of the material British Virgin Islands and U.S. federal income tax considerations associated with our operations and the acquisition, ownership and disposition of our Ordinary Shares set forth in Section E, “Taxation,” of Item 10 of our Annual Report, filed with the SEC on March 20, 2025 and incorporated by reference herein.

DILUTION

If you invest in our Ordinary Shares in this offering, your ownership interest will be diluted to the extent of the difference between the price per Ordinary Share you pay in this offering and the net tangible book value per Ordinary Share immediately after this offering. We calculate net tangible book value per share by dividing the net tangible book value, which is tangible assets less total liabilities, by the number of outstanding Ordinary Shares. Dilution represents the difference between the portion of the amount per share paid by purchasers of Ordinary Shares in this offering and the pro forma as adjusted net tangible book value per share of our Ordinary Shares immediately after giving effect to this offering. As of December 31, 2024, our net tangible book value was $77.9 million, or $0.78 per Ordinary Share.

After giving effect to the issuance of 4,469,382 Ordinary Shares following the exercise of warrants to purchase 4,469,382 Ordinary Shares at a price of $1.70 per share on January 3, 2025, our pro forma net tangible book value as of December 31, 2024 would have been approximately $85.2 million or $0.82 per Ordinary Share.

After giving further effect to the sale of 10,000,000 Ordinary Shares at a price of $2.00 per share on May 6, 2025, and after deducting aggregate offering expenses paid by us, our pro forma net tangible book value as of December 31, 2024 would have been approximately $103.6 million or $0.90 per Ordinary Share.

After giving effect to the sale of our Ordinary Shares in the aggregate amount of $100,000,000 at an assumed offering price of $2.58 per Ordinary Share, the last reported sale price of our Ordinary Shares on The Nasdaq on May 16, 2025 and after deducting commissions and estimated offering expenses payable by us, our as adjusted net tangible book value as of December 31, 2024 would have been $200.3 million, or $1.31 per Ordinary Share. This would represent an immediate increase in net tangible book value of $0.41 per Ordinary Share to our existing shareholders and an immediate dilution in net tangible book value of $1.27 per Ordinary Share to new investors in this offering.

The following table illustrates this calculation on a per Ordinary Share basis. The as adjusted information is illustrative only and will adjust based on the actual price to the public, the actual number of Ordinary Shares sold and other terms of the offering determined at the time our Ordinary Shares are sold pursuant to this prospectus supplement. The Ordinary Shares sold in this offering, if any, will be sold from time to time at various prices.

The foregoing discussion and table are based on 100,039,519 Ordinary Shares outstanding as of December 31, 2024, and exclude, as of that date, the following number of shares outstanding:

We may choose to raise additional capital due to market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans. To the extent that additional capital is raised through the sale of equity or convertible debt securities, the issuance of these securities may result in further dilution to our shareholders.

PLAN OF DISTRIBUTION

We entered into the Sales Agreement with the Sales Agents on May 19, 2025. Under the terms of the Sales Agreement, we may offer and sell up to $100,000,000 of our Ordinary Shares from time to time through or to Cantor, acting as the sole designated sales agent and/or principal. A copy of the Sales Agreement will be filed as an exhibit to a Current Report on Form 6-K and will be incorporated by reference into this prospectus supplement.

Upon delivery of a placement notice to Cantor and subject to the terms and conditions of the Sales Agreement, Cantor may sell shares of our Ordinary Shares by any method permitted by law deemed to be an “at the market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act. We may instruct Cantor not to sell Ordinary Shares if the sales cannot be effected at or above the price designated by us from time to time. We or Cantor may suspend the offering of Ordinary Shares upon notice and subject to other conditions.

We will pay the Sales Agents a commission, in cash, at a rate of 3.0% of the gross sales price per share sold through the Sales Agreement. Because there is no minimum offering amount required as a condition of this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. We have also agreed to reimburse the Sales Agents for certain specified expenses, including the fees and disbursements of their legal counsel in an amount not to exceed (a) $100,000 in connection with the execution of the Sales Agreement, (b) $20,000 per calendar quarter thereafter payable in connection with each representation date with respect to which the Company is obligated to deliver a certificate pursuant to the terms of the Sales Agreement, and (c) $50,000 for each program “refresh” (filing of a new registration statement, prospectus or prospectus supplement relating to the ordinary shares and/or an amendment of the Sales Agreement) executed pursuant to the Sales Agreement. We estimate that the total expenses for the offering, excluding compensation payable to the Sales Agents the terms of the Sales Agreement, will be approximately $280,420.

Settlement for sales of our Ordinary Shares will occur on the business day immediately following the date on which any sales are made, or on such other date that is agreed upon by us and Cantor in connection with a particular transaction, in return for payment of the net proceeds to us. Sales of our Ordinary Shares as contemplated in this prospectus supplement will be settled through the facilities of The Depository Trust Company or by such other means as we and Cantor may agree upon. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

Cantor will use its commercially reasonable efforts, consistent with its sales and trading practices, to solicit offers to purchase the Ordinary Shares under the terms and subject to the conditions set forth in the Sales Agreement. In connection with the sale of the Ordinary Shares on our behalf, each Sales Agent will be deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation of the Sales Agents will be deemed to be underwriting commissions or discounts. We have agreed to provide indemnification and contribution to each Sales Agent against certain civil liabilities, including liabilities under the Securities Act.

The offering of our Ordinary Shares pursuant to the Sales Agreement will terminate upon the termination of the Sales Agreement as permitted therein. We and the Sales Agents may each terminate the Sales Agreement at any time upon ten days’ prior notice.

The Sales Agents and their respective affiliates may in the future provide various investment banking, commercial banking and other financial services for us and our affiliates, for which services they may in the future receive customary fees. To the extent required by Regulation M, the Sales Agents will not engage in any market-making activities involving our Ordinary Shares while the offering is ongoing under this prospectus supplement.

This prospectus supplement and the accompanying prospectus may be made available in electronic format on a website maintained by each of the Sales Agents, and each of the Sales Agents may distribute this prospectus supplement and the accompanying prospectus electronically. 

EXPENSES

We estimate that the total expenses of this offering payable by us, excluding the Sales Agents’ commissions, will be approximately $280,420 as follows:

LEGAL MATTERS

Certain legal matters with respect to British Virgin Islands law in connection with this offering are being passed upon for us by Harney Westwood & Riegels (BVI) LP. Certain matters of U.S. federal and New York law are being passed upon for us by Patterson Belknap Webb & Tyler LLP, New York, New York. The Sales Agents are being represented in connection with this offering by DLA Piper LLP (US), New York, New York.

EXPERTS

The financial statements of SEALSQ Corp as of and for the year ended December 31, 2024 and December 31, 2023, in each case incorporated by reference in this prospectus supplement from the Company’s Annual Report on Form 20-F for the year ended December 31, 2024 have been so incorporated in reliance on the reports of BDO Ltd, an independent registered public accounting firm, given upon the authority of said firm as experts in accounting and auditing. The financial statements of SEALSQ Corp Predecessor as of and for the year ended December 31, 2022, incorporated by reference in this prospectus supplement from the Company’s Annual Report on Form 20-F for the year ended December 31, 2024 have been so incorporated in reliance on the report of BDO Rhône Alpes, an independent registered public accounting firm, given upon their authority as experts in accounting and auditing.

ENFORCEABILITY OF CIVIL LIABILITIES

We are incorporated under the laws of the British Virgin Islands and our principal executive offices are located outside the United States. Most of our directors and officers and those of our subsidiaries are residents of countries other than the United States. Substantially all of our and our subsidiaries’ assets and a substantial portion of the assets of our directors and officers are located outside the United States. As a result, it may be difficult or impossible for United States investors to effect service of process within the United States upon us, our directors or officers or our subsidiaries, or to realize against us or them judgments obtained in United States courts, including judgments predicated upon the civil liability provisions of the securities laws of the United States or any state in the United States.

Furthermore, there is substantial doubt that courts in jurisdictions outside the U.S. (i) would enforce judgments of U.S. courts obtained in actions against us or our directors or officers based upon the civil liability provisions of applicable U.S. federal and state securities laws or (ii) would enforce, in original actions, liabilities against us or our directors or officers based on those laws.

WHERE YOU CAN FIND MORE INFORMATION

We have filed with the SEC a registration statement on Form F-3 under the Securities Act, relating to this offering of securities. This prospectus supplement does not contain all of the information contained in the registration statement. The rules and regulations of the SEC allow us to omit certain information from this prospectus supplement that is included in the registration statement. Statements made in this prospectus supplement concerning the contents of any contract, agreement or other document are summaries of all material information about the documents summarized, but are not complete descriptions of all terms of these documents. If we filed any of these documents as an exhibit to the registration statement, you may read the document itself for a complete description of its terms.

We are subject to the informational requirements of the Exchange Act applicable to foreign private issuers. In accordance with the Exchange Act, we file reports, including annual reports on Form 20-F containing financial statements audited by an independent accounting firm. We also furnish to the SEC, under cover of Reports of Foreign Private Issuer on Form 6-K, material information required to be made public by us or filed by us with and made public by any stock exchange or distributed by us to our shareholders. Such reports and other information filed with the SEC are available to the public over the internet at the SEC’s website at http://www.sec.gov. We also generally make available on our own website (www.sealsq.com) our quarterly and year-end financial statements as well as other information.

As a foreign private issuer, we are exempt from the rules under the Exchange Act prescribing the furnishing and content of proxy statements to shareholders, and our officers, directors and principal shareholders are exempt from the “short-swing profits” reporting and liability provisions contained in Section 16 of the Exchange Act and related Exchange Act rules. In addition, we are not required under the Exchange Act to file periodic reports and financial statements as frequently or as promptly as U.S. companies whose securities are registered under the Exchange Act.

We maintain a corporate website at www.sealsq.com. Information contained on, or that can be accessed through, our website does not constitute a part of this prospectus supplement. We have included our website address in this prospectus supplement solely as an inactive textual reference.

INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

The SEC allows us to incorporate by reference our publicly filed reports into this prospectus supplement, which means that information included in those reports is considered part of this prospectus supplement. Because we are incorporating by reference future filings with the SEC, this prospectus supplement is continually updated and those future filings may modify or supersede some of the information included or incorporated by reference in this prospectus supplement. This means that you must look at all of the SEC filings that we incorporate by reference to determine if any of the statements in this prospectus supplement or in any document previously incorporated by reference have been modified or superseded. This prospectus supplement incorporates by reference the documents listed below and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934 (the “Exchange Act”) (in each case, other than those documents or the portions of those documents furnished, rather than filed), and, to the extent designated therein, reports on Form 6-K, until the offering of the securities under the registration statement of which this prospectus supplement and accompanying base prospectus form a part is terminated or completed:

The SEC maintains an Internet site at http://www.sec.gov that contains reports, proxy and information statements, and other information regarding issuers like us that file electronically with the SEC.

We will also incorporate by reference all subsequent Annual Reports on Form 20-F that we file with the SEC. In addition, we will incorporate by reference certain future materials furnished to the SEC on Form 6-K after the date of the initial registration statement, but only to the extent specifically indicated in those submissions or in a future prospectus supplement. Each subsequently filed Annual Report should be deemed to supersede entirely each earlier filed Annual Report and the materials furnished on an earlier Form 6-K and, unless explicitly stated otherwise, such earlier reports should not be deemed to be part of this prospectus supplement and you should not rely upon statements made in those earlier periodic reports. In all cases, you should rely on the later information over different information in this prospectus supplement.

We will furnish without charge to you, on written or oral request, a copy of any or all of the above documents, other than exhibits to such documents which are not specifically incorporated by reference therein. You should direct any requests for documents to:

SEALSQ Corp

Avenue Louis-Casaï 58

1216 Cointrin Switzerland

Tel: 011-41-22-594-3000

Fax: 011-41-22-594-3001

The information relating to us contained in this prospectus supplement is not comprehensive and should be read together with the information contained in the incorporated documents. Descriptions contained in the incorporated documents as to the contents of any contract or other document may not contain all of the information which is of interest to you. You should refer to the copy of such contract or other document filed as an exhibit to our filings.

PROSPECTUS

$500 million

Ordinary Shares

Warrants

Subscription Rights

Units

of

SEALSQ Corp

__________

This prospectus relates to the offer and sale by SEALSQ Corp from time to time of Ordinary Shares, warrants to purchase Ordinary Shares, subscription rights or units. We may also offer securities that may be issuable upon the conversion, exercise or exchange of warrants or subscription rights. We refer to all of the foregoing securities collectively as the “securities” in this prospectus. The aggregate initial offering price of the securities that we may offer and sell under this prospectus will not exceed $500 million.

Each time we sell securities pursuant to this prospectus, we will provide in a supplement to this prospectus the price and any other material terms of any such offering. Any prospectus supplement may also add, update or change information contained in this prospectus. You should read this prospectus and any applicable prospectus supplement, as well as the documents incorporated by reference or deemed incorporated by reference into this prospectus, carefully before you invest in any securities. This prospectus may not be used to offer or sell securities unless accompanied by a prospectus supplement.

We may, from time to time, offer to sell the securities, through public or private transactions, directly or through underwriters, agents or dealers, on or off the Nasdaq Capital Market, or Nasdaq, at prevailing market prices or at privately negotiated prices. If any underwriters, agents or dealers are involved in the sale of any of these securities, the applicable prospectus supplement will set forth the names of the underwriter, agent or dealer, and any applicable fees, commissions or discounts.

Our Ordinary Shares are listed on the Nasdaq Capital Market under the ticker symbol “LAES.” The last reported sale price of our Ordinary Shares on the Nasdaq Capital Market on March 24, 2025 was $3.16 per share.

Investing in our securities involves a high degree of risk. Please carefully consider the risks discussed in this prospectus under “Risk Factors” beginning on page 4 and the “Risk Factors” in “Item 3.D: Key Information—Risk Factors” of our most recent Annual Report on Form 20-F incorporated by reference in this prospectus and in any applicable prospectus supplement for a discussion of the factors you should consider carefully before deciding to purchase these securities.

Neither the Securities and Exchange Commission, nor any other regulatory body has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Prospectus dated April 2, 2025.

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we have filed with the SEC, utilizing a “shelf” registration process. Under this shelf process, we may sell the securities or any combination of the securities described in this prospectus in one or more offerings for an aggregate offering amount of up to $500 million. This prospectus does not contain all of the information set forth in the registration statement, certain parts of which are omitted in accordance with the rules and regulations of the SEC. Accordingly, you should refer to the registration statement and its exhibits for further information about us and our securities. Copies of the registration statement and its exhibits are on file with the SEC. Statements contained in this prospectus concerning the documents we have filed with the SEC are not intended to be comprehensive, and in each instance we refer you to a copy of the actual document filed as an exhibit to the registration statement or otherwise filed with the SEC.

Each time we offer our securities pursuant to this registration statement, we will provide you with a prospectus supplement that will describe the specific amounts, prices and terms of the securities we offer. The prospectus supplement may also add, update or change information contained in this prospectus. This prospectus, together with applicable prospectus supplements and the documents incorporated by reference in this prospectus and any prospectus supplements, includes all material information relating to this offering. Please read carefully both this prospectus and any prospectus supplement together with additional information described below under “Where You Can Find More Information” and “Incorporation of Certain Documents by Reference.”

This prospectus does not contain all of the information provided in the registration statement that we filed with the Commission. For further information about us or our securities, you should refer to that registration statement, which you can obtain from the Commission as described below under “Where You Can Find More Information” and “Incorporation of Certain Documents by Reference.”

You should rely only on the information incorporated by reference or provided in this prospectus or any prospectus supplement. “Incorporated by reference” means that we can disclose important information to you by referring you to another document filed separately with the SEC. We have not authorized anyone to provide you with different information. We are offering to sell, and seeking offers to buy, our securities only in jurisdictions where offers and sales are permitted. We are not making, nor will we make, an offer to sell securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus and any supplement to this prospectus is current only as of the dates on their respective covers. Our business, financial condition, results of operations and prospects may have changed since that date.

We prepare our financial statements in United States dollars and in accordance with United States generally accepted accounting principles.

Certain figures included in this prospectus have been subject to rounding adjustments. Accordingly, figures shown as totals in certain tables may not be an arithmetic aggregation of the figures that precede them.

In this prospectus, “we,” “us,” “our,” the “Company” and “SEALSQ” refers to SEALSQ Corp. Any reference to “WISeKey” is to WISeKey International Holding AG and its subsidiaries, except where the context otherwise requires.

All references in this prospectus to “$,” “U.S. Dollars” and “dollars” are to United States dollars.

This prospectus and the information incorporated by reference herein and therein include trademarks, service marks and trade names owned by us or other companies. Solely for convenience, trademarks referred to in this prospectus, including logos, artwork and other visual displays, may appear without the ® or ™ symbols. We do not intend our use or display of other companies’ trade names or trademarks to imply a relationship with, or endorsement or sponsorship of us by, any other companies. All trademarks, service marks and trade names included or incorporated by reference into this prospectus or an accompanying prospectus supplement are the property of their respective owners.

ABOUT OUR COMPANY

This summary highlights selected information contained elsewhere in this prospectus that we consider important. This summary does not contain all of the information you should consider before investing in our securities. You should read this summary together with the entire prospectus, including the risks related to our business, our industry and investing in our securities that we describe under “Risk Factors,” and our consolidated financial statements and the related notes incorporated by reference in this prospectus before making an investment in our securities.

SEALSQ is a leading innovator in Post-Quantum Technology hardware and software solutions. Our technology seamlessly integrates Semiconductors, PKI (Public Key Infrastructure), and Provisioning Services, with a strategic emphasis on developing state-of-the-art Quantum Resistant Cryptography and Semiconductors designed to address the urgent security challenges posed by quantum computing. Our products are engineered to safeguard critical systems, enhancing resilience and security across diverse industries.

SEALSQ was established as a subsidiary of WISeKey International Holding AG, combining decades of expertise in cryptographic security and trusted digital infrastructure. Headquartered in Switzerland, we operate across Europe, the United States, and other strategic markets. Our solutions provide the foundation of digital trust for businesses and governments worldwide.

SEALSQ delivers integrated digital security solutions that combine four critical components into a unified offering: Root-of-Trust, Secure Chips, trusted Identity Generation and Management (PKI), and Personalization Services. Together, these components ensure the confidentiality, integrity, and authenticity of connected devices and digital communications.

SEALSQ delivers integrated digital security solutions that combine four critical components into a unified offering: Root-of- Trust, Secure Chips, trusted Identity Generation and Management (PKI), and Personalization Services. Together, these components ensure the confidentiality, integrity, and authenticity of connected devices and digital communications.

Our offerings are structured around four foundational technology pillars:

SEALSQ’s comprehensive product range meets the growing demand for secure, certified solutions across industries:

SEALSQ solutions serve high-growth industries requiring secure, scalable, and certified solutions. Some examples of the use cases of our products are as follows:

SEALSQ semiconductors and PKI services contribute to secure millions of objects: luxury products, routers, gateways, utilities meters, E.V. chargers, drones, authentication dongles, storage memory USB sticks, medical devices, connected door-locks, and a variety of other electronic consumers devices.

Corporate Information

SEALSQ Corp is a BVI business company incorporated and existing under the laws of the British Virgin Islands. Our registered office in the British Virgin Islands is at Craigmuir Chambers, Road Town, Tortola, VG 1110, British Virgin Islands. Our principal executive offices and effective place of management are located at Avenue Louis-Casaï 58, 1216 Cointrin, Switzerland. Our telephone number from the United States is 011 41 22 594 3000. Our website can be accessed at www.SEALSQ.com. The information on or linked to on our website is not a part of this prospectus.

RISK FACTORS

Investing in our securities involves significant risks. Before making an investment decision, you should carefully consider the risks described under “Risk Factors” in the applicable prospectus supplement and under “Item 3.D: Key Information—Risk Factors” in our most recent Annual Report on Form 20-F, or any updates in our Reports on Form 6-K, together with all of the other information appearing in this prospectus or incorporated by reference into this prospectus and any applicable prospectus supplement, in light of your particular investment objectives and financial circumstances.

The risks so described are not the only risks facing us. Additional risks not presently known to us or that we currently deem immaterial may also impair our business operations. Our business, financial condition and results of operations could be materially adversely affected by any of these risks. The trading price of our securities could decline due to any of these risks, and you may lose all or part of your investment. The discussion of risks includes or refers to forward-looking statements; you should read the explanation of the qualifications and limitations on such forward-looking statements discussed elsewhere in this prospectus.

FORWARD-LOOKING STATEMENTS

This prospectus contains forward-looking statements. These forward-looking statements include information about possible or assumed future results of our operations or our performance. Words such as “expects,” “intends,” “plans,” “believes,” “anticipates,” “estimates,” “projects,” “forecasts” and variations of such words and similar expressions, as they relate to us, WISeKey International Holding S.A., our parent company (“WISeKey”), our management or third parties, are intended to identify the forward-looking statements. Forward-looking statements include statements regarding our business strategy, financial performance, results of operations, market data, events or developments that SEALSQ expects or anticipates will occur in the future, as well as any other statements which are not historical facts. Although we believe that the expectations reflected in such forward-looking statements are reasonable, no assurance can be given that such expectations will prove to have been correct. These statements involve known and unknown risks and are based upon a number of assumptions and estimates which are inherently subject to significant uncertainties and contingencies, many of which are beyond our control. Actual results may differ materially from those expressed or implied by such forward-looking statements. Forward-looking statements include, but are not limited to, statements we make regarding:

These forward-looking statements include, but are not limited to, statements relating to:

The preceding list is not intended to be an exhaustive list of all of our forward-looking statements. The forward-looking statements are based on our beliefs, assumptions and expectations of future performance, taking into account the information currently available to us and are only predictions based upon our current expectations and projections about future events. There are important factors that could cause our actual results, levels of activity, performance or achievements to differ materially from the results, levels of activity, performance or achievements expressed or implied by these forward-looking statements. Those factors include, in addition to those set forth in Item 3.D. Risk Factors and those included elsewhere in this report, among others, the following:

Given these risks and uncertainties, you should not place undue reliance on forward-looking statements as a prediction of actual results.

WE UNDERTAKE NO OBLIGATION TO PUBLICLY UPDATE OR REVISE ANY FORWARD-LOOKING STATEMENTS CONTAINED IN THIS PROSPECTUS OR THE DOCUMENTS TO WHICH WE REFER YOU IN THIS PROSPECTUS, TO REFLECT ANY CHANGE IN OUR EXPECTATIONS WITH RESPECT TO SUCH STATEMENTS OR ANY CHANGE IN EVENTS, CONDITIONS OR CIRCUMSTANCES ON WHICH ANY STATEMENT IS BASED, EXCEPT AS REQUIRED BY LAW.

CAPITALIZATION

Our capitalization will be set forth in a prospectus supplement to this prospectus or in a report of foreign private issuer on Form 6-K subsequently furnished to the SEC and specifically incorporated herein by reference.

USE OF PROCEEDS

Except as otherwise provided in the applicable prospectus supplement, we intend to use the net proceeds of this offering for general corporate purposes, which may include but are not limited to merger and acquisition activities, working capital and research and development expenditure.

The intended application of proceeds from the sale of any particular offering of securities using this prospectus will be described in the accompanying prospectus supplement relating to such offering. The precise amount and timing of the application of these proceeds will depend on our funding requirements and the availability and costs of other funds.

DESCRIPTION OF ORDINARY SHARES

The following description of our share structure is a summary of the material terms of our amended and restated memorandum and articles of association and BVI corporate law regarding our shares and the holders thereof. This description contains all material information concerning our shares but does not purport to be complete.

General

We are a British Virgin Islands Business Company (company number 2095496) and our affairs are governed by our memorandum and articles of association (“Articles”), the BVI Business Companies Act (“BVI Act”) and common law of the British Virgin Islands. Based upon the Articles, we are authorized to issue a maximum of 210,000,000 shares in two classes as follows:

As of the date of this prospectus, 104,508,901 Ordinary Shares are issued and outstanding and 1,499,800 Class F Shares are issued and outstanding. No preferred shares are issued or outstanding or authorized by our Articles. The following description summarizes the material terms of our shares as set out more particularly in our Articles. Because it is only a summary, it may not contain all the information that is important to you.

Share Rights

Each Ordinary Share confers upon the shareholder:

Our Ordinary Shareholders have no conversion, pre-emptive or other subscription rights and there are no sinking fund or redemption provisions applicable to the Ordinary Shares.

Each Class F Share confers upon the shareholder:

The Class F Shares are subject to mandatory and automatic redemption, in the event of a change of control (being the acquisition by any person or entity, alone or jointly, of more than 50% of the voting rights of any Class F Shareholder which is a corporate entity), as determined by the Company’s board of directors, in exchange for the issuance of new Ordinary Shares at a ratio of five (5) Ordinary Shares for each one (1) Class F Share redeemed.

The Class F Shares are non-transferable.

The Company and the holders of the Class F Shares have entered into a Class F Shareholders’ Agreement that provides, among other things, that the holders of Class F Shares:

Register of Members

Under the BVI Act, the shares are deemed to be issued when the name of the shareholder is entered in the register of members. Our register of members will be maintained by our transfer agent, Computershare Inc.

If:

a shareholder of the company, or any person who is aggrieved by the omission, inaccuracy or delay, may apply to the British Virgin Islands Courts for an order that the register be rectified, and the court may either refuse the application or order the rectification of the register, and may direct the Company to pay all costs of the application and any damages the applicant may have sustained.

Dividends

We have not paid any cash dividends on our shares to date. The payment of cash dividends in the future will be dependent upon our revenues and earnings. Under the laws of the British Virgin Islands and our Articles, we may only pay a dividend or make a distribution to our shareholders if, following such dividend or distribution, the value of our assets will exceed our liabilities and we will be able to pay our debts as they fall due. In addition, the Second Tranche Notes prohibit us and our subsidiaries from paying dividends or other cash distributions, except for intercompany transfers to us and payments to WISeKey.

Comparison of Shareholder Rights

DESCRIPTION OF WARRANTS

The following description, together with the additional information we may include in any applicable prospectus supplements, summarizes the material terms and provisions of the warrants that we may offer under this prospectus and the related warrant agreements and warrant certificates. While the terms summarized below will apply generally to any warrants that we may offer under this prospectus, we will describe the particular terms of any series of warrants that we may offer in more detail in the applicable prospectus supplement. If we indicate in the prospectus supplement, the terms of any warrants offered under that prospectus supplement may differ from the terms described below. However, no prospectus supplement shall fundamentally change the terms that are set forth in this prospectus or offer a security that is not registered and described in this prospectus at the time of its effectiveness. Specific warrant agreements will contain additional important terms and provisions and will be incorporated by reference as an exhibit to the registration statement that includes this prospectus or as an exhibit to a report filed under the Exchange Act.

General

The applicable prospectus supplement will describe the terms of the warrants, including as applicable:

Warrants will be offered and exercisable for U.S. dollars only and will be in registered form only.

Holders of warrants will be able to exchange warrant certificates for new warrant certificates of different denominations, present warrants for registration of transfer, and exercise warrants at the designated office of the warrant agent in the applicable prospectus supplement. Prior to the exercise of any warrants, holders of the warrants to purchase Ordinary Shares will not have any rights of holders of Ordinary Shares, including the right to receive payments of dividends, if any, or to exercise any applicable right to vote.

Certain Risk Considerations

Any warrants we issue will involve a degree of risk, including risks arising from fluctuations in the price of the underlying Ordinary Shares and general risks applicable to the securities market (or markets) on which the underlying securities trade, as applicable. Prospective purchasers of the warrants will need to recognize that the warrants may expire worthless, and, thus, purchasers should be prepared to sustain a total loss of the purchase price of their warrants. This risk reflects the nature of a warrant as an asset that, other factors held constant, tends to decline in value over time and that may, depending on the price of the underlying securities, become worthless when it expires. The trading price of a warrant at any time is expected to increase if the price of or, if applicable, the dividend rate on, the underlying securities increases. Conversely, the trading price of a warrant is expected to decrease as the time remaining to expiration of the warrant decreases and as the price of or, if applicable, the dividend rate on, the underlying securities, decreases. Assuming all other factors are held constant, the more a warrant is “out-of-the-money” (i.e., the more the exercise price exceeds the price of the underlying securities and the shorter its remaining term to expiration), the greater the risk that a purchaser of the warrant will lose all or part of his or her investment. If the price of the underlying securities does not rise before the warrant expires to an extent sufficient to cover a purchaser’s cost of the warrant, the purchaser will lose all or part of his or her investment in the warrant upon expiration.

In addition, prospective purchasers of the warrants should be experienced with respect to options and option transactions, should understand the risks associated with options and should reach an investment decision only after careful consideration, with their financial advisers, of the suitability of the warrants in light of their particular financial circumstances and the information discussed in this prospectus and, if applicable, the prospectus supplement. Before purchasing, exercising or selling any warrants, prospective purchasers and holders of warrants should carefully consider, among other things:

Some of the factors referred to above are in turn influenced by various political, economic and other factors that can affect the trading price of the underlying securities and should be carefully considered prior to making any investment decisions.

Purchasers of the warrants should further consider that the initial offering price of the warrants may be in excess of the price that a purchaser of options might pay for a comparable option in a private, less liquid transaction. In addition, it is not possible to predict the price at which the warrants will trade in the secondary market or whether any such market will be liquid. We may, but will not be obligated to, file an application to list any warrants on a U.S. national securities exchange. To the extent that any warrants are exercised, the number of warrants outstanding will decrease, which may result in a lessening of the liquidity of the warrants. Finally, the warrants will constitute our direct, unconditional and unsecured obligations and, as such, will be subject to any changes in our perceived creditworthiness.

Exercise of Warrants

Each holder of a warrant will be entitled to purchase that number or amount of underlying securities, at the exercise price, as will in each case be described in the prospectus supplement relating to the offered warrants. After the close of business on the warrant expiration date (which may be extended by us), unexercised warrants will become void.

Holders may exercise warrants by delivering to the warrant agent payment as provided in the applicable prospectus supplement of the amount required to purchase the underlying securities purchasable upon exercise, together with the information set forth on the reverse side of the warrant certificate. Warrants will be deemed to have been exercised upon receipt of payment of the exercise price, subject to the receipt of the warrant certificate evidencing the exercised warrants. Upon receipt of payment and the warrant certificate properly completed and duly executed at the designated office of the warrant agent in the applicable prospectus supplement, we will, as soon as practicable, issue and deliver the underlying securities purchasable upon such exercise. If fewer than all of the warrants represented by a warrant certificate are exercised, we will issue a new warrant certificate for the remaining amount of warrants.

Amendments and Supplements to Warrant Agreements

We may amend or supplement the warrant agreement without the consent of the holders of the warrants issued under the agreement to effect changes that are not inconsistent with the provisions of the warrants and that do not adversely affect the interests of the holders of warrants.

DESCRIPTION OF SUBSCRIPTION RIGHTS

We may issue subscription rights to purchase our Ordinary Shares. These subscription rights may be issued independently or together with any other security offered hereby and may or may not be transferable by the shareholder receiving the subscription rights in such offering. In connection with any offering of subscription rights, we may enter into a standby arrangement with one or more underwriters or other purchasers pursuant to which the underwriters or other purchasers may be required to purchase any securities remaining unsubscribed for after such offering.

The prospectus supplement relating to any subscription rights we offer, if any, will, to the extent applicable, include specific terms relating to the offering, including some or all of the following:

The description in the applicable prospectus supplement of any subscription rights we offer will not necessarily be complete and will be qualified in its entirety by reference to the applicable subscription right agreement, which will be filed with the SEC if we offer subscription rights. For more information on how you can obtain copies of the applicable subscription right agreement if we offer subscription rights, see “Where You Can Find More Information” below and “Incorporation of Certain Documents by Reference” below. We urge you to read the applicable subscription right agreement and any applicable prospectus supplement in their entirety.

DESCRIPTION OF UNITS

We may issue units comprised of one or more of the other securities described in this prospectus in any combination. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each included security. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately, at any time or at any time before a specified date.

The applicable prospectus supplement will describe:

The applicable prospectus supplement will describe the terms of any units. The preceding description and any description of units in the applicable prospectus supplement does not purport to be complete and is subject to and is qualified in its entirety by reference to the unit agreement and, if applicable, collateral arrangements and depositary arrangements relating to such units. For more information on how you can obtain copies of the applicable unit agreement if we offer units, see “Where You Can Find More Information” below and “Incorporation of Certain Documents by Reference” below. We urge you to read the applicable unit agreement and any applicable prospectus supplement in their entirety.

TAXATION

The material BVI and U.S. federal income tax consequences relating to the purchase, ownership and disposition of any of the securities offered by this prospectus will be set forth in the applicable prospectus supplement offering those securities or incorporated by reference from our Annual Report on Form 20-F or other public filings we make with the SEC.

PLAN OF DISTRIBUTION

We may sell the securities described in this prospectus through underwriters or dealers, through agents, directly to one or more purchasers, “at-the-market” offerings, negotiated transactions, block trades or through a combination of these methods. The applicable prospectus supplement will describe the terms of the offering of the securities, including:

We may distribute the securities from time to time in one or more transactions at:

Only underwriters named in the prospectus supplement will be underwriters of the securities offered by the prospectus supplement.

If we use underwriters in the sale, the underwriters will either acquire the securities for their own account and may resell the securities from time to time in one or more transactions at a fixed public offering price or at varying prices determined at the time of sale, or sell the securities on a “best efforts, minimum/maximum basis” when the underwriters agree to do their best to sell the securities to the public. We may offer the securities to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. Any public offering price and any discounts or concessions allowed or re- allowed or paid to dealers may change from time to time.

If we use a dealer in the sale of the securities being offered pursuant to this prospectus or any prospectus supplement, the securities will be sold directly to the dealer, as principal. The dealer may then resell the securities to the public at varying prices to be determined by the dealer at the time of resale.

Our ordinary shares are listed on the Nasdaq Capital Market. Unless otherwise specified in the related prospectus supplement, all securities we offer, other than ordinary shares, will be new issues of securities with no established trading market. Any underwriter may make a market in these securities, but will not be obligated to do so and may discontinue any market making at any time without notice. We may apply to list securities that we offer on an exchange, but we are not obligated to do so. Therefore, there may not be liquidity or a trading market for any series of securities.

We may sell the securities directly or through agents we designate from time to time. We will name any agent involved in the offering and sale of securities and we will describe any commissions we may pay the agent in the applicable prospectus supplement.

We may authorize agents or underwriters to solicit offers by institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. We will describe the conditions to these contracts and the commissions we must pay for solicitation of these contracts in the applicable prospectus supplement.

In connection with the sale of the securities, underwriters, dealers or agents may receive compensation from us or from purchasers of the securities for whom they act as agents in the form of discounts, concessions or commissions. Underwriters may sell the securities to or through dealers, and those dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters or commissions from the purchasers for whom they may act as agents. Underwriters, dealers and agents that participate in the distribution of the securities, and any institutional investors or others that purchase securities directly and then resell the securities, may be deemed to be underwriters, and any discounts or commissions received by them from us and any profit on the resale of the securities by them may be deemed to be underwriting discounts and commissions under the Securities Act of 1933.

LEGAL MATTERS

Certain legal matters with respect to British Virgin Islands law in connection with this offering are being passed upon for us by Harney Westwood & Riegels LP. Certain matters of U.S. federal and New York law are being passed upon for us by Patterson Belknap Webb & Tyler LLP, New York, New York.

EXPERTS

The financial statements of SEALSQ Corp as of and for the year ended December 31, 2024 and December 31, 2023, in each case incorporated by reference in this prospectus from the Company’s Annual Report on Form 20-F for the year ended December 31, 2024 have been so incorporated in reliance on the reports of BDO Ltd, an independent registered public accounting firm, given upon the authority of said firm as experts in accounting and auditing. The financial statements of SEALSQ Corp Predecessor as of and for the year ended December 31, 2022, incorporated by reference in this prospectus from the Company’s Annual Report on Form 20-F for the year ended December 31, 2024 have been so incorporated in reliance on the report of BDO Rhône Alpes, an independent registered public accounting firm, given upon their authority as experts in accounting and auditing.

INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

The SEC allows us to incorporate by reference our publicly filed reports into this prospectus, which means that information included in those reports is considered part of this prospectus. Because we are incorporating by reference future filings with the SEC, this prospectus is continually updated and those future filings may modify or supersede some of the information included or incorporated by reference in this prospectus. This means that you must look at all of the SEC filings that we incorporate by reference to determine if any of the statements in this prospectus or in any document previously incorporated by reference have been modified or superseded. This prospectus incorporates by reference the documents listed below and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934 (the “Exchange Act”) (in each case, other than those documents or the portions of those documents furnished, rather than filed), and, to the extent designated therein, reports on Form 6-K, until the offering of the securities under the registration statement of which this prospectus forms a part is terminated or completed:

The SEC maintains an Internet site at http://www.sec.gov that contains reports, proxy and information statements, and other information regarding issuers like us that file electronically with the SEC.

We will also incorporate by reference all subsequent Annual Reports on Form 20-F that we file with the SEC. In addition, we will incorporate by reference certain future materials furnished to the SEC on Form 6-K after the date of the initial registration statement, but only to the extent specifically indicated in those submissions or in a future prospectus supplement. Each subsequently filed Annual Report should be deemed to supersede entirely each earlier filed Annual Report and the materials furnished on an earlier Form 6-K and, unless explicitly stated otherwise, such earlier reports should not be deemed to be part of this prospectus or any accompanying prospectus supplement and you should not rely upon statements made in those earlier periodic reports. In all cases, you should rely on the later information over different information in this prospectus or any accompanying prospectus supplement.

We will furnish without charge to you, on written or oral request, a copy of any or all of the above documents, other than exhibits to such documents which are not specifically incorporated by reference therein. You should direct any requests for documents to:

SEALSQ Corp

Avenue Louis-Casaï 58

1216 Cointrin

Switzerland

Tel: 011-41-22-594-3000

Fax: 011-41-22-594-3001

The information relating to us contained in this prospectus is not comprehensive and should be read together with the information contained in the incorporated documents. Descriptions contained in the incorporated documents as to the contents of any contract or other document may not contain all of the information which is of interest to you. You should refer to the copy of such contract or other document filed as an exhibit to our filings.

WHERE YOU CAN FIND MORE INFORMATION

We have filed with the SEC a registration statement on Form F-3 under the Securities Act, relating to this offering of securities. As permitted by SEC rules, this prospectus does not contain all of the information contained in the registration statement of which this prospectus forms a part. Statements made in this prospectus concerning the contents of any contract, agreement or other document are summaries of all material information about the documents summarized, but are not complete descriptions of all terms of these documents. If we filed any of these documents as an exhibit to the registration statement, you may read the document itself for a complete description of its terms.

We are subject to the informational requirements of the Exchange Act applicable to foreign private issuers. In accordance with the Exchange Act, we file reports, including annual reports on Form 20-F containing financial statements audited by an independent accounting firm. We also furnish to the SEC, under cover of Reports of Foreign Private Issuer on Form 6-K, material information required to be made public by us or filed by us with and made public by any stock exchange or distributed by us to our shareholders. Such reports and other information filed with the SEC are available to the public over the internet at the SEC’s website at http://www.sec.gov. We also generally make available on our own website (www.sealsq.com) our half-year and year-end financial statements as well as other information.

As a foreign private issuer, we are exempt from the rules under the Exchange Act prescribing the furnishing and content of proxy statements to shareholders, and our officers, directors and principal shareholders are exempt from the “short-swing profits” reporting and liability provisions contained in Section 16 of the Exchange Act and related Exchange Act rules. In addition, we are not required under the Exchange Act to file periodic reports and financial statements as frequently or as promptly as U.S. companies whose securities are registered under the Exchange Act.

We maintain a corporate website at www.sealsq.com. Information contained on, or that can be accessed through, our website does not constitute a part of this prospectus. We have included our website address in this prospectus solely as an inactive textual reference.

ENFORCEABILITY OF CIVIL LIABILITIES

We are incorporated under the laws of the British Virgin Islands and our principal executive offices are located outside the United States. Most of our directors and officers and those of our subsidiaries are residents of countries other than the United States. Substantially all of our and our subsidiaries’ assets and a substantial portion of the assets of our directors and officers are located outside the United States. As a result, it may be difficult or impossible for United States investors to effect service of process within the United States upon us, our directors or officers or our subsidiaries, or to realize against us or them judgments obtained in United States courts, including judgments predicated upon the civil liability provisions of the securities laws of the United States or any state in the United States.

Furthermore, there is substantial doubt that courts in jurisdictions outside the U.S. (i) would enforce judgments of U.S. courts obtained in actions against us or our directors or officers based upon the civil liability provisions of applicable U.S. federal and state securities laws or (ii) would enforce, in original actions, liabilities against us or our directors or officers based on those laws.

EXPENSES

The following is an estimate of the expenses (all of which are to be paid by us) that we may incur in connection with the securities being registered hereby. Each prospectus supplement describing an offering of securities will reflect the estimated expenses related to the offering of securities under that prospectus supplement.

SEALSQ Corp

Up to $100,000,000 Ordinary Shares

Prospectus Supplement

Cantor

Maxim Group LLC

May 19, 2025