UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM F-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

OCULIS HOLDING AG

(Exact name of registrant as specified in its charter)

Bahnhofstrasse 20

CH-6300

Zug, Switzerland

Telephone: +41 41 711 39 60

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Oculis US Inc.

One Gateway Center

300 Washington Street, Suite 702

Newton, MA 02458

Telephone: +1 617 928 5886

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this Registration Statement.

If only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box: ☐

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box. ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a registration statement pursuant to General Instruction I.C. or a post-effective amendment thereto that shall become effective upon filing with the Securities and Exchange Commission, or the Commission, pursuant to Rule 462(e) under the Securities Act, check the following box. ☒

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.C. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. ☐

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933. Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards† provided pursuant to Section 7(a)(2)(B) of Securities Act. ☐

† The term “new or revised accounting standard” refers to any update issued by the Financial Accounting Standards Board to its Accounting Standards Codification after April 5, 2012.

EXPLANATORY NOTE

This registration statement contains two prospectuses:

The base prospectus immediately follows this explanatory note. The specific terms of any securities to be offered pursuant to the base prospectus will be specified in a prospectus supplement to the base prospectus.

The prospectus relating to the sales agreement immediately follows the base prospectus. The ordinary shares that may be offered, issued and sold by the registrant under the sales agreement prospectus is included in the securities that may be offered, issued and sold by the registrant under the base prospectus. Upon termination of the sales agreement with Leerink Partners, any portion of the $100,000,000 included in the sales agreement prospectus that is not sold pursuant to the sales agreement will be available for sale in other offerings pursuant to the base prospectus and a corresponding prospectus supplement.

PROSPECTUS

Oculis Holding AG

Ordinary Shares

Debt Securities

Warrants

Units

Oculis Holding AG, a Swiss stock corporation (Aktiengesellschaft) or any selling security holders may offer, from time to time, in one or more offerings, ordinary shares, senior debt securities, subordinated debt securities, warrants and units, which we collectively refer to as the securities. We and/or our selling security holders may offer and sell any combination of the securities described in this prospectus in different series, at times, in amounts, at prices and on terms to be determined at or prior to the time of each offering. This prospectus describes the general terms of these securities and the general manner in which these securities will be offered. We will provide the specific terms of these securities in supplements to this prospectus. The prospectus supplements will also describe the specific manner in which these securities will be offered and may also supplement, update or amend information contained in this prospectus. You should read this prospectus and any applicable prospectus supplement before you invest.

The securities covered by this prospectus may be offered through one or more underwriters, dealers and agents, or directly to purchasers. If any underwriters, dealers or agents are involved in the sale of our securities with respect to which this prospectus is being delivered, the names of such underwriters, dealers or agents and any applicable fees, commissions or discounts and over-allotment options will be set forth in a prospectus supplement. The price to the public of such securities and the net proceeds that we expect to receive from such sale will also be set forth in a prospectus supplement. Unless otherwise set forth in a prospectus supplement, we will not receive any proceeds from the sale of securities by selling security holders. For general information about the distribution of securities offered, please see “Plan of Distribution” beginning on page 14 of this prospectus.

YOU SHOULD READ THIS PROSPECTUS AND ANY SUPPLEMENT TO THIS PROSPECTUS CAREFULLY BEFORE YOU INVEST.

Our ordinary shares are listed on the Nasdaq Global Market, or Nasdaq, and the Nasdaq Iceland Main Market, or Nasdaq Iceland, under the symbol “OCS.” On March 2, 2026, the last sale price of our ordinary shares as reported by was $28.61 per ordinary share. On March 2, 2026, the last sale price of our ordinary shares as reported by Nasdaq Iceland was ISK 3,150.00 per ordinary share. The applicable prospectus supplement will contain information, where applicable, as to any other listing, if any, on Nasdaq or any securities market or other securities exchange of the securities covered by the prospectus supplement. There is currently no market through which debt securities, warrants or units may be sold and purchasers may not be able to resell debt securities, warrants or units purchased under this prospectus. This may affect the pricing of any debt securities, warrants or units in the secondary market, the transparency and availability of trading prices, the liquidity of the debt securities, warrants or units and the extent of issuer regulation. Prospective purchasers of our securities are urged to obtain current information as to the market prices of our securities, where applicable.

We are a “foreign private issuer” as defined under the U.S. Securities and Exchange Commission, or the SEC, and, as such, we have elected to comply with certain reduced public company reporting requirements for this prospectus and future filings. Please see “Implications of Being a Foreign Private Issuer.”

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

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties described under the heading “Risk Factors” beginning on page 3 of this prospectus. In addition, please review any additional risk factors in any accompanying prospectus supplement, any free writing prospectus and any documents we incorporate by reference.

The date of this prospectus is March 4, 2026.

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS

This prospectus is a part of an automatic registration statement that we filed with the SEC using a “shelf” registration process available to us as a “well-known seasoned issuer,” as defined in Rule 405 under the Securities Act of 1933, as amended, or the Securities Act. Under this shelf registration process, we and/or our selling security holders may, from time to time, sell any combination of the securities described in this prospectus. No limit exists on the aggregate number or amount of securities we and/or our selling security holders may sell pursuant to the registration statement of which this prospectus is a part. This prospectus provides you with a general description of the securities that may be offered by us and/or our selling security holders.

Each time we and/or our selling security holders offer a type or series of securities, we will provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities. The prospectus supplement will contain specific information about the nature of the persons offering securities and the terms of the securities being offered at that time. The prospectus supplement may also add, update or change information contained in this prospectus. Before buying any of the securities that we and/or our selling security holders are offering, you should carefully read both this prospectus and any prospectus supplement with all of the information incorporated by reference in this prospectus, as well as the additional information described under the heading “Where You Can Find More Information” and “Incorporation by Reference.” These documents contain important information that you should consider when making your investment decision. We have filed or incorporated by reference exhibits to the registration statement of which this prospectus forms a part. You should read the exhibits carefully for provisions that may be important to you.

To the extent there is a conflict between the information contained in this prospectus, on the one hand, and the information contained in any prospectus supplement or in any document incorporated by reference in this prospectus, on the other hand, you should rely on the information in this prospectus, provided that if any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a prospectus supplement or a document incorporated by reference in this prospectus—the statement in the document having the later date modifies or supersedes the earlier statement.

The information contained in this prospectus, any applicable prospectus supplement or any document incorporated by reference in this prospectus is accurate only as of their respective dates, regardless of the time of delivery of this prospectus, any applicable prospectus supplement or the documents incorporated by reference in this prospectus or the sale of any securities. Our business, financial condition, results of operations and prospects may have changed materially since those dates.

Neither we nor any underwriters, dealers or agents have authorized anyone to provide you with information that is different from that contained in this prospectus, any amendment or supplement to this prospectus, or any free writing prospectus we may authorize to be delivered or made available to you. Neither we nor any underwriters, dealers or agents take responsibility for, or provide assurance as to the reliability of, any other information that others may give you. This prospectus does not constitute an offer to sell or the solicitation of an offer to buy any securities other than the securities described in this prospectus or an offer to sell or the solicitation of an offer to buy such securities in any circumstances in which such offer or solicitation is unlawful.

For investors outside the United States: Neither we nor any underwriters, dealers or agents have taken any action that would permit the offering or possession or distribution of this prospectus in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the offering of the securities described herein and the distribution of this prospectus outside the United States.

Unless otherwise noted or the context otherwise requires, references in this prospectus to “Oculis,” “the Company,” “our Company,” “we,” “us” or “our” refer to Oculis Holding AG and its subsidiaries.

TRADEMARKS AND TRADENAMES

This prospectus includes trademarks, tradenames and service marks, certain of which belong to us and others that are the property of other organizations. Solely for convenience, trademarks, tradenames and service marks referred to in this prospectus appear without the ®, ™ and SM symbols, but the absence of those symbols is not intended to indicate, in any way, that we will not assert our rights or that the applicable owner will not assert its rights to these trademarks, tradenames and service marks to the fullest extent under applicable law. We do not intend our use or display of other parties’ trademarks, tradenames or service marks to imply, and such use or display should not be construed to imply, a relationship with, or endorsement or sponsorship of us by, these other parties.

PRESENTATION OF FINANCIAL INFORMATION

In this prospectus, unless otherwise specified, all monetary amounts are in U.S. dollars, all references to “U.S. dollars,” “$,” “US$” and “USD” mean United States dollars and all references to “CHF” mean Swiss francs.

Our consolidated financial statements are presented in Swiss francs and in accordance with IFRS Accounting Standards, or IFRS, as issued by the International Accounting Standards Board, or IASB. None of the financial statements were prepared in accordance with generally accepted accounting principles in the United States, or U.S. GAAP.

MARKET AND INDUSTRY DATA

This prospectus contains estimates, projections, and other information concerning our industry and business, as well as data regarding market research, estimates, and forecasts prepared by our management. Information that is based on estimates, forecasts, projections, market research, or similar methodologies is inherently subject to uncertainties, and actual events or circumstances may differ materially from events and circumstances that are assumed in this information. The industry in which we operate is subject to a high degree of uncertainty and risk due to a variety of factors, including those described in the section titled “Risk Factors.” Unless otherwise expressly stated, we obtained this industry, business, market, and other data from reports, research surveys, studies, and similar data prepared by market research firms and other third parties, industry and general publications, government data, and similar sources. In some cases, we do not expressly refer to the sources from which this data is derived. In that regard, when we refer to one or more sources of this type of data in any paragraph, you should assume that other data of this type appearing in the same paragraph is derived from sources which we paid for, sponsored, or conducted, unless otherwise expressly stated or the context otherwise requires. While have compiled, extracted, and reproduced industry data from these sources, have not independently verified the data. Forecasts and other forward-looking information with respect to industry, business, market, and other data are subject to the same qualifications and additional uncertainties regarding the other forward-looking statements in this prospectus. See “Special Note Regarding Forward-Looking Statements.”

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus and our financial statements and other documents and information incorporated by reference in this prospectus contain forward-looking statements, including statements concerning our industry, our operations, our anticipated financial performance and financial condition, and our business plans and growth strategy and product development efforts. These statements constitute forward-looking statements within the meaning of Section 27A of the Securities Act, and Section 21E of the Exchange Act. Many of the forward-looking statements contained in this prospectus can be identified by the use of forward-looking words such as “anticipate,” “believe,” “could,” “expect,” “should,” “plan,” “intend,” “estimate” and “potential,” among others. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of their dates. These forward-looking statements are based on estimates and assumptions by our management that, although we believe to be reasonable, are inherently uncertain and subject to a number of risks and uncertainties.

The following represent some, but not necessarily all, of the factors that could cause actual results to differ from historical results or those anticipated or predicted by our forward-looking statements:

These forward-looking statements are based on information available as of the date of this prospectus and current expectations, forecasts and assumptions, and involve a number of judgments, risks and uncertainties. Our actual results or performance could differ materially from those expressed in, or implied by, any forward-looking statements relating to those matters. Accordingly, forward-looking statements should not be relied upon as representing our views as of any subsequent date, and we do not undertake any obligation to update forward-looking statements to reflect events or circumstances after the date they were made, whether as a result of new information, future events or otherwise, except as may be required under applicable securities laws. Accordingly, you should not place undue reliance on these forward-looking statements in deciding to invest in our securities. As a result of a number of known and unknown risks and uncertainties, our actual results or performance may be materially different from those expressed or implied by these forward-looking statements. You should refer to the section titled “Risk Factors” for a discussion of important factors that may cause our actual results to differ materially from those expressed or implied by our forward-looking statements. As a result of these factors, we cannot assure you that the forward-looking statements in this prospectus

will prove to be accurate. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material. In light of the significant uncertainties in these forward-looking statements, you should not regard these statements as a representation or warranty by us or any other person that we will achieve our objectives and plans in any specified time frame, or at all. We undertake no obligation to publicly update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

RISK FACTORS

Investing in our securities involves a high degree of risk. The prospectus supplement and any related free writing prospectus applicable to each offering of our securities will contain a discussion of the risks applicable to an investment in our securities. Prior to making a decision about investing in our securities, you should carefully consider the specific factors discussed under the section in the applicable prospectus supplement captioned “Risk Factors,” together with all of the other information contained or incorporated by reference in the prospectus supplement or appearing or incorporated by reference in this prospectus. See “Where You Can Find More Information” and “Incorporation by Reference.” You should also consider the risks, uncertainties and assumptions discussed under “Part I—Item 3.D—Risk Factors” of our most recent Annual Report on Form 20-F and reports on Form 6-K we file after the date of this prospectus, that are incorporated herein by reference, as may be amended, supplemented or superseded from time to time by other reports we file with the SEC in the future. The risks and uncertainties we have described are not the only ones we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also affect our operations. Past financial performance may not be a reliable indicator of future performance, and historical trends should not be used to anticipate results in future periods. If any of these risks actually occurs, our business, financial condition, results of operations or cash flow could be seriously harmed. This could cause the trading price of our securities to decline, resulting in a loss of all or part of your investment. Please also carefully read the section titled “Special Note Regarding Forward-Looking Statements.”

CAPITALIZATION

We intend to include information about our capitalization and indebtedness in the prospectus supplement relating to the specific offering.

OFFER STATISTICS AND EXPECTED TIMETABLE

We and/or our selling security holders may offer ordinary shares, debt securities, warrants and units, in one or more offerings and on a continuous or delayed basis. The actual price of the securities that we will offer pursuant hereto will depend on a number of factors that may be relevant as of the time of offer. See “Plan of Distribution.”

REASONS FOR THE OFFER AND USE OF PROCEEDS

Unless otherwise indicated in the applicable prospectus supplement or in any free writing prospectus that we may authorize to be provided to you in connection with a specific offering, we intend to use any net proceeds from the sale of securities under this prospectus for research and development, progression of our clinical programs, general corporate purposes and working capital. Accordingly, we will have significant discretion in the use of any net proceeds. Additional information on the use of net proceeds we receive from the sale of securities covered by this prospectus may be set forth in the prospectus supplement relating to the specific offering.

We will not receive any proceeds from the sale by selling security holders of the securities covered by this prospectus.

SELLING SECURITY HOLDERS

Selling security holders are persons or entities that, directly or indirectly, have acquired or will from time to time acquire from us, our securities. Such selling security holders may be parties to registration rights agreements with us, or we otherwise may have agreed or will agree to register their securities for resale. The initial purchasers of our securities, as well as their transferees, pledges, donees or successors, all of whom we refer to as “selling security holders,” may from time to time offer and sell our securities pursuant to this prospectus and any applicable prospectus supplement.

The applicable prospectus supplement will set forth the name of each selling security holder and the number of securities beneficially owned by such selling security holder that are covered by such prospectus supplement. The applicable prospectus supplement will also disclose whether any of the selling security holders have held any position

or office with, has been employed by or otherwise has had a material relationship with us during the three years prior to the date of the applicable prospectus supplement.

THE OFFER AND LISTING

Our ordinary shares are currently traded on Nasdaq and Nasdaq Iceland under the symbol “OCS.” Our ordinary shares began trading on Nasdaq on March 3, 2023 and began trading on Nasdaq Iceland on April 23, 2024.

DESCRIPTION OF SHARE CAPITAL AND ARTICLES OF ASSOCIATION

For information regarding our share capital and Articles of Association, please refer to the description of our securities and the full text of our Articles of Association, which are filed as Exhibit 2.5 and Exhibit 1.1, respectively, to our Annual Report, as well as any amendments thereto reflected in our subsequent filings with the SEC, all of which are incorporated by reference herein.

DESCRIPTION OF DEBT SECURITIES

The debt securities will be our direct general obligations. The debt securities will be either senior debt securities or subordinated debt securities and may be secured or unsecured and may be convertible into and/or exchangeable for other securities, including our ordinary shares. The debt securities will be issued under one or more separate indentures between our company and a financial institution that will act as trustee. Senior debt securities will be issued under a senior indenture. Subordinated debt securities will be issued under a subordinated indenture. Each of the senior indenture and the subordinated indenture is referred to individually as an indenture and collectively as the indentures. Each of the senior debt trustee and the subordinated debt trustee is referred to individually as a trustee and collectively as the trustees. The material terms of any indenture will be set forth in the applicable prospectus supplement.

We have summarized certain terms and provisions of the indentures. The summary is not complete. The indentures are subject to and governed by the Trust Indenture Act of 1939, as amended. The senior indenture and subordinated indenture are substantially identical, except for the provisions relating to subordination.

Neither indenture will limit the amount of debt securities that we may issue. We may issue debt securities up to an aggregate principal amount as we may authorize from time to time. The applicable prospectus supplement will describe the terms of any debt securities being offered. These terms will include some or all of the following:

Senior Debt

We may issue under the senior indenture the debt securities that will constitute part of our senior debt. These senior debt securities will rank equally and pari passu with all our other unsecured and unsubordinated debt.

Subordinated Debt

We may issue under the subordinated indenture the debt securities that will constitute part of our subordinated debt. These subordinated debt securities will be subordinate and junior in right of payment, to the extent and in the manner set forth in the subordinated indenture, to all our “senior indebtedness.” “Senior indebtedness” is defined in the subordinated indenture and generally includes obligations of, or guaranteed by, us for borrowed money, or as evidenced by bonds, debentures, notes or other similar instruments, or in respect of letters of credit or other similar instruments, or to pay the deferred purchase price of property or services, or as a lessee under capital leases, or as secured by a lien on any asset of ours. “Senior indebtedness” does not include the subordinated debt securities or any other obligations specifically designated as being subordinate in right of payment to, or pari passu with, the subordinated debt securities. In general, the holders of all senior indebtedness are first entitled to receive payment in full of such senior indebtedness before the holders of any of the subordinated debt securities are entitled to receive a payment on account of the principal or interest on the indebtedness evidenced by the subordinated debt securities in certain events. These events include:

Authentication and Delivery

We will deliver the debt securities to the trustee for authentication, and the trustee will authenticate and deliver the debt securities upon our written order.

Events of Default

When we use the term “Event of Default” in the indentures with respect to the debt securities of any series, set forth below are some examples of what we mean:

If an Event of Default (other than an Event of Default specified in clause (4) above) with respect to the debt securities of any series then outstanding occurs and is continuing, then either the trustee or the holders of not less than 25% in principal amount of the securities of all such series then outstanding in respect of which an Event of Default has occurred may by notice in writing to us declare the entire principal amount of all debt securities of the affected series, and accrued interest, if any, to be due and payable immediately, and upon any such declaration the same shall become immediately due and payable.

If an Event of Default described in clause (4) above occurs and is continuing, then the principal amount of all the debt securities then outstanding and accrued interest shall be and become due immediately and payable without any declaration, notice or other action by any holder of the debt securities or the trustee.

The trustee will, within 90 days after the occurrence of any default actually known to it, give notice of the default to the holders of the debt securities of that series, unless the default was already cured or waived. Unless there is a default in paying principal or interest when due, the trustee can withhold giving notice to the holders if it determines in good faith that the withholding of notice is in the interest of the holders.

Satisfaction, Discharge and Defeasance

We may discharge our obligations under each indenture, except as to:

when:

In addition, unless the applicable prospectus supplement and supplemental indenture otherwise provide, we may elect either (i) to have our obligations under each indenture discharged with respect to the outstanding debt securities of any series, or legal defeasance, or (ii) to be released from our obligations under each indenture with respect to certain covenants applicable to the outstanding debt securities of any series, or covenant defeasance. Legal defeasance means that we will be deemed to have paid and discharged the entire indebtedness represented by the outstanding debt securities of such series under such indenture and covenant defeasance means that we will no longer be required to comply with the obligations with respect to such covenants (and an omission to comply with such obligations will not constitute a default or event of default).

In order to exercise legal defeasance or covenant defeasance with respect to outstanding debt securities of any series:

in each case sufficient without reinvestment, in the written opinion of a nationally recognized firm of independent public accountants, to pay and discharge, and which shall be applied by the trustee to pay and discharge, all of the principal and interest at due date or maturity or if we have made irrevocable arrangements satisfactory to the trustee for the giving of notice of redemption by the trustee, the redemption date;

We are required to furnish to each trustee an annual statement as to compliance with all conditions and covenants under the indenture.

DESCRIPTION OF WARRANTS

We may issue warrants to purchase debt securities, ordinary shares or other securities. We may issue warrants independently or together with other securities. Warrants sold with other securities may be attached to or separate from the other securities. We will issue warrants under one or more warrant agreements between our company and a warrant agent that we will name in the applicable prospectus supplement.

The prospectus supplement relating to any warrants we offer will include specific terms relating to the offering. These terms will include some or all of the following:

The terms of any warrants to be issued and a description of the material provisions of the applicable warrant agreement will be set forth in the applicable prospectus supplement.

DESCRIPTION OF UNITS

We may issue units comprised of one or more of the other securities that may be offered under this prospectus, in any combination. As specified in the applicable prospectus supplement, we may issue units consisting of our ordinary shares, debt securities, warrants or any combination of such securities. 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 provisions described in this section, as well as those described under “Description of Share Capital and Articles of Association” (including the description of our securities and the full text of our articles of association, which are filed as Exhibit 2.5 and Exhibit 1.1, respectively, to our Annual Report, as well as any amendments thereto reflected in our subsequent filings with the SEC, all of which are incorporated by reference herein), “Description of Debt Securities” and “Description of Warrants” will apply to the securities included in each unit, to the extent relevant and as may be updated in any prospectus supplements.

The description in the applicable prospectus supplement of any units we offer will not necessarily be complete and will be qualified in its entirety by reference to the applicable unit agreement, which will be filed with the SEC if we offer 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.”

LIMITATIONS AFFECTING SHAREHOLDERS OF A SWISS COMPANY

Form and Transfer of Shares

Form of the Shares

Ordinary shares may be issued as ordinary uncertificated securities within the meaning of article 973c CO (Wertrechte) and/or global certificates. In accordance with article 973c CO, we maintain a register of uncertificated securities (Wertrechtebuch). We may create intermediated securities (Bucheffekten) for ordinary shares.

Upon its registration with the share register, a shareholder may at any time request that we issue a written confirmation of the ordinary shares held by such shareholder. However, the shareholder has no right to request the printing and delivery of share certificates nor the conversion of ordinary shares issued in one form into another form. We may, however, at any time print and deliver certificates for registered (single certificates or global certificates) and, with the consent of the shareholder, delete without replacement issued share certificates, which have been returned to it. We may convert ordinary shares from one form into another form at any time and without the approval of the shareholders. We shall bear the cost associated with any such conversion.

Transfer of Shares

Ordinary shares in uncertificated form (Wertrechte) may only be transferred by way of assignment. ordinary shares or the beneficial interest in ordinary shares, as applicable, credited in a securities account may only be transferred when a credit of the relevant intermediated securities to the acquirer’s securities account is made in accordance with applicable rules.

Share Register

We maintain a share register (Aktienbuch), or the Share Register, in which the owners of the ordinary shares are registered with name, address and nationality (in case of legal entities the registered office). In relation to the Company, only those shareholders registered in the Share Register are recognized as shareholders.

Pursuant to article 4 of our articles of association, or the Articles of Association, acquirers of ordinary shares are, upon request and presentation of evidence of the transfer, registered as shareholders with voting rights in the Share Register if they explicitly declare to hold ordinary shares in their own name and for their own account.

The board of directors shall implement the necessary directions for maintaining the Share Register and it may issue corresponding regulations or guidelines. The board of directors may delegate such tasks.

In the invitation to the general meeting, the board of directors shall announce the record date for registration in the Share Register that is relevant with respect to the right to attend and vote.

We have the right to delete entries in the Share Register retroactively as of the date of the entry if the registration has been made on the basis of false information. We may give the relevant shareholder or nominee, in advance, the opportunity, to be heard. The relevant shareholder or nominee must be informed of the deletion without delay.

Registration and Voting Right Restrictions

The Articles of Association contain the following registration restrictions:

1. Regulatory Registration and Voting Right Restrictions. According to article 4 of the Articles of Association, the board of directors may refuse the registration of an acquirer of ordinary shares in the Share Register as a shareholder with voting rights or cancel an already occurred registration of ordinary shares with voting rights from the Share Register, if (a) the number of ordinary shares held or acquired directly or indirectly or acting in concert with third parties or as an organized group by such acquirer exceeds 15% of the total number of voting rights of the Company pursuant to the entry in the commercial register, and (b) such acquirer has not submitted prior to the

acquisition of such ordinary shares an orderly tender offer to all shareholders with a minimum price of the higher of (i) the volume weighted average price of the last 60 trading days prior to the publication of the tender offer, or (ii) the highest price paid by such acquirer in the 12 months preceding to the publication of the tender offer.

Those associated through capital, voting power, joint management, beneficial ownership or in any other way, or joining for the acquisition of shares shall be regarded as one acquirer for the purposes of article 4 of the Articles of Association. Acquirers who do not meet the legal or regulatory requirements according to article 4 of the Articles of Association shall be entered in the Share Register as shareholder without voting rights for ordinary shares exceeding the limit of 15%. In case of an already occurred registration, ordinary shares exceeding the limit of 3% may be cancelled from the Share Register as ordinary shares with voting rights and instead be registered as ordinary shares without voting rights. The board of directors may enact regulations governing the details of such registration restriction. Nominees do not constitute as acquirers within the meaning of article 4 of the Articles of Association. After hearing the person concerned, we may cancel the registrations in the Share Register if those registrations were based on false information of the acquirer. In addition, according to article 4 of the Articles of Association, the board of directors may refuse the exercise of voting rights of a shareholder in excess of 15% of the total number of voting rights of the Company pursuant to the entry in the commercial register, if such shareholder does not meet the legal or regulatory requirements according to article 4 of the Articles of Association.

2. Registration and Voting Right Restrictions for ordinary shares held through Nominees. The registration and voting right restrictions in connection with the regulatory registration and voting right restrictions described above are also applicable to ordinary shares held through nominees. Accordingly, article 4 of the Articles of Association provides that, if, any beneficial owner should as a result of such registration of a nominee being made or upheld, directly or indirectly, formally, constructively or beneficially own, or otherwise control or alone or together with third parties, hold a number of shares exceeding 3% of the total number of voting rights of the Company pursuant to the entry in the commercial register and the nominee does not, expressly declare in the registration application that it is holding the shares on its own account, and the nominee does not confirm in writing that it is willing to disclose the names, addresses and shareholdings of the persons on whose account they hold 0.5% or more of the share capital, the board of directors may refuse to register (or cancel an already occurred registration of) the nominee holding ordinary shares for the account of such beneficial owner with respect to any ordinary shares in excess of such restriction. The board of directors may make the registration with voting rights of the ordinary shares held by a nominee subject to conditions, limitations and reporting requirements and may impose or adjust such conditions, limitations and requirements once registered and may enter into agreements with nominees in this regard. Further, the voting right restrictions pursuant to article 4 of the Articles of Association as set out above also apply to ordinary shares, which are held by a nominee for the account of a person exceeding the threshold of 15% (regulatory voting right restrictions).

Apart from the registration and voting rights restrictions as described above, there are no restrictions on the transferability of the ordinary shares in the Articles of Association.

Ownership of Shares by Non-Swiss Residents

Except for the limitations on voting rights described above applicable to shareholders generally and the sanctions referred to below, there is no limitation under Swiss law or our Articles of Association on the right of non-Swiss residents or nationals to own ordinary shares or to exercise voting rights attached to the ordinary shares.

Foreign Investment and Exchange Control Regulations in Switzerland

Other than in connection with government sanctions imposed on certain persons from, in or related to the Republic of Iraq, Myanmar (Burma), Zimbabwe, Sudan, the Democratic Republic of Congo, Belarus, the Democratic People’s Republic of Korea (North Korea), Lebanon, Iran, Somalia, Guinea, Libya, Syria, Guinea-Bissau, Central African Republic, Yemen, Burundi, the Republic of South Sudan, Venezuela, Nicaragua, Haiti, Moldova, Guatemala, persons and organizations with connections to “ISIL” (“Da'esh”) and the “Al-Qaeda” or the Taliban groups, persons and organizations supporting Hamas or the Palestinian Islamic Jihad, certain persons in connection with the assassination of Rafik Hariri as well as measures in connection with the situation in Ukraine, there are currently no governmental laws, decrees or regulations in Switzerland that restrict the export or import of capital, including, but not limited to, Swiss foreign exchange controls on the payment of dividends, interest or liquidation proceeds, if any, to non-resident holders of shares.

Pre-emptive Rights and Advance Subscription Rights

Swiss law provides that any share issue, whether for cash or non-cash consideration, is subject to the prior approval at a general meeting of shareholders. Shareholders are granted certain pre-emptive rights (Bezugsrechte) to subscribe for new issues of shares and advance subscription rights (Vorwegzeichnungsrechte) to subscribe for warrants, convertible bonds or similar debt instruments with option rights in proportion to the nominal amount of shares held. Pursuant to the Articles of Association, a resolution adopted at a general meeting by a majority of two-thirds of the votes represented at the meeting is required to repeal, limit or suspend pre-emptive rights.

PLAN OF DISTRIBUTION

We and/or our selling security holders may offer and sell the securities in one or more of the following ways (or in any combination) from time to time:

The prospectus supplement will state the terms of the offering of the securities, including:

Any public offering price and any discounts or concessions allowed or reallowed or paid to dealers may be changed from time to time.

If underwriters are used in the sale, the securities will be acquired by the underwriters for their own account and may be resold from time to time in one or more transactions, including:

Unless otherwise stated in a prospectus supplement, the obligations of the underwriters to purchase any securities will be conditioned on customary closing conditions and the underwriters will be obligated to purchase all of such series of securities, if any are purchased.

The securities may be sold through agents from time to time. The prospectus supplement will name any agent involved in the offer or sale of the securities and any commissions paid to them. Generally, any agent will be acting on a commercially reasonable efforts basis for the period of its appointment.

Sales to or through one or more underwriters or agents in at-the-market offerings will be made pursuant to the terms of a distribution agreement with the underwriters or agents. Such underwriters or agents may act on an agency basis or on a principal basis. During the term of any such agreement, shares may be sold on a daily basis on any stock exchange, market or trading facility on which the ordinary shares are traded, in privately negotiated transactions or otherwise as agreed with the underwriters or agents. The distribution agreement will provide that any ordinary share sold will be sold at negotiated prices or at prices related to the then prevailing market prices for our ordinary shares. Therefore, exact figures regarding proceeds that will be raised or commissions to be paid cannot be determined at this time and will be described in a prospectus supplement. Pursuant to the terms of the distribution agreement, we and/or our selling security holders may also agree to sell, and the relevant underwriters or agents may agree to solicit offers to purchase, blocks of our ordinary shares or other securities. The terms of each such distribution agreement will be described in a prospectus supplement.

We and/or our selling security holders may authorize underwriters, dealers or agents to solicit offers by certain purchasers to purchase the securities 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. The contracts will be subject only to those conditions set forth in the prospectus supplement, and the prospectus supplement will set forth any commissions paid for solicitation of these contracts.

Underwriters and/or agents may be entitled under agreements entered into with us to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, or to contribution with respect to payments which the underwriters or agents may be required to make.

The prospectus supplement may also set forth whether or not underwriters may over-allot or effect transactions that stabilize, maintain or otherwise affect the market price of the securities at levels above those that might otherwise prevail in the open market, including, for example, by entering stabilizing bids, effecting syndicate covering transactions or imposing penalty bids.

Underwriters and agents may be customers of, engage in transactions with, or perform services for us and our affiliates in the ordinary course of business.

Each series of securities will be a new issue of securities and will have no established trading market, other than our ordinary shares, which are listed on Nasdaq. Any underwriters to whom securities are sold for public offering and sale may make a market in the securities, but such underwriters will not be obligated to do so and may discontinue any market making at any time without notice. The securities, other than our ordinary shares, may or may not be listed on a national securities exchange.

TAXATION

The material U.S. federal income tax and, to the extent applicable, material Swiss tax consequences relating to the purchase, ownership and disposition of any of the securities offered by this prospectus will be set forth in the prospectus supplement pertaining to those securities.

EXPENSES

The following table sets forth the expenses (other than underwriting discounts and commissions or agency fees and other items constituting underwriters’ or agents’ compensation, if any) expected to be incurred by us in connection with a possible offering of securities registered under this registration statement. All amounts are estimated.

(1) This registration statement relates to the registration of securities having an indeterminate maximum aggregate amount. Payment of the registration fee has been deferred and will be calculated and paid in accordance with Rule 456(b) and Rule 457(r) under the Securities Act.

(2) These fees are calculated based on the securities offered and the number of issuances and accordingly cannot be estimated at the time.

LEGAL MATTERS

The validity of the securities offered hereby on behalf of the Company and certain other matters of Swiss law, including matters of Swiss income tax law, will be passed upon for us by VISCHER AG, Basel, Switzerland. Certain matters of U.S. federal law will be passed upon for us by Cooley LLP, New York, New York. Additional legal matters may be passed on for us, or any underwriters, dealers or agents by counsel we will name in the applicable prospectus supplement.

EXPERTS

The financial statements and management’s assessment of the effectiveness of internal control over financial reporting (which is included in Management’s report on internal control over financial reporting) incorporated in this Prospectus by reference to the Annual Report on Form 20-F for the year ended December 31, 2025 have been so incorporated in reliance on the report of PricewaterhouseCoopers SA, an independent registered accounting firm, given on the authority of said firm as experts in auditing and accounting. PricewaterhouseCoopers SA is a member of EXPERTsuisse — Swiss Expert Association for Audit, Tax and Fiduciary.

SERVICE OF PROCESS AND ENFORCEABILITY OF CIVIL LIABILITIES

We are organized under the laws of Switzerland and our registered office and domicile is located in Zug, Switzerland. Moreover, a number of our directors and executive officers are not residents of the United States, and a substantial portion of the assets of such persons are located outside the U.S. As a result, it may not be possible for investors to effect service of process within the United States upon us or upon such persons or to enforce against us or them judgments obtained in United States courts, including judgments in actions predicated upon the civil liability provisions of U.S. federal securities laws.

We have been advised by our Swiss counsel, VISCHER AG, that there is doubt as to the enforceability in Switzerland of original actions, or in actions for enforcement of judgments of U.S. courts, of civil liabilities to the extent solely predicated upon the federal and state securities laws of the United States. Original actions against persons in Switzerland based solely upon the U.S. federal or state securities laws are governed, among other things, by the principles set forth in the Swiss Federal Act on Private International Law of December 18, 1987, as amended, or the PILA. The PILA provides that the application of provisions of non-Swiss law by the courts in Switzerland shall be precluded if the result would be incompatible with Swiss public policy (ordre public). Also, mandatory provisions of Swiss law may be applicable regardless of any other law that would otherwise apply.

We have appointed Oculis US, Inc as our agent to receive service of process with respect to any action brought against us in the United States District Court for the Southern District of New York under the federal securities laws of the United States or of any state in the United States or any action brought against us in the Supreme Court of the State of New York in the County of New York under the securities laws of the State of New York.

Switzerland and the United States do not, as of the date of this proxy statement/prospectus, have a treaty providing for reciprocal recognition of and enforcement of judgments in civil and commercial matters. The recognition and enforcement of a judgment of the courts of the United States in Switzerland is governed by the principles set forth in the PILA. This statute provides in principle that a judgment rendered by a non-Swiss court may be enforced in Switzerland only if:

WHERE YOU CAN FIND MORE INFORMATION

We are subject to the periodic reporting and other information requirements of the Exchange Act as applicable to a “foreign private issuer,” and we will file annual reports and other information from time to time with the SEC in accordance with such requirements. Our SEC filings will be available to the public on the internet at a website maintained by the SEC located at www.sec.gov.

We also maintain a website at www.oculis.com. We will make available on our website, free of charge, the following documents as soon as reasonably practicable after they are electronically filed with, or furnished to, the SEC: our annual reports on Form 20-F; our reports on Form 6-K; amendments to these documents; and other information as may be required by the SEC. The information contained on, or that may be accessed through, our website is not part of, and is not incorporated into, this prospectus. This prospectus is part of a registration statement that we filed with the SEC and does not contain all of the information in the registration statement. You should review the information and exhibits in the registration statement for further information on us and the securities that we are offering. Forms of any indenture or other documents establishing the terms of the offered securities are filed as exhibits to the registration statement of which this prospectus forms a part or under cover of a Report on Form 6-K and incorporated in this prospectus by reference. Statements in this prospectus or any prospectus supplement about these documents are summaries and each statement is qualified in all respects by reference to the document to which it refers. You should read the actual documents for a more complete description of the relevant matters.

INCORPORATION BY REFERENCE

The SEC allows us to incorporate by reference much of the information that we file with the SEC, which means that we can disclose important information to you by referring you to those publicly available documents. The information that we incorporate by reference in this prospectus is considered to be 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 Exchange Act (in each case, other than those documents or the portions of those documents furnished, rather than filed, and, except as may be noted in any such Form 6-K, exhibits filed on such form that are related to such information), until the offering of the securities under the registration statement of which this prospectus forms a part is terminated or completed:

You can obtain any of the filings incorporated by reference in this prospectus through us or from the SEC through the SEC’s website at www.sec.gov. Our filings with the SEC, including our annual reports on Form 20-F and reports on Form 6-K and exhibits incorporated in and amendments to those reports, are also available free of charge on our website (www.oculis.com) as soon as reasonably practicable after they are filed with, or furnished to, the SEC. The reference to our website is an inactive textual reference only, and information contained therein or connected thereto is not incorporated into this prospectus or the registration statement of which it forms a part. We will provide to each person, including any beneficial owner, to whom this prospectus is delivered, a copy of any or all the reports or documents incorporated by reference in this prospectus at no cost, upon written or oral request to us at the following address and telephone number:

Oculis Holding AG
Bahnhofstrasse 20
CH-6300
Zug, Switzerland
Attn: Investor Relations
+41 41 711 39 60

Oculis Holding AG

Ordinary Shares

Debt Securities

Warrants

Units

PROSPECTUS

PROSPECTUS SUPPLEMENT

(TO PROSPECTUS DATED MARCH 4, 2026)

Oculis Holding AG

Up to $100,000,000

Ordinary Shares

We have entered into an amended and restated sales agreement, or the Sales Agreement, with Leerink Partners LLC, or Leerink Partners, dated March 4, 2026, relating to the sale of our ordinary shares, nominal value CHF 0.01 per share, offered by this prospectus supplement. In accordance with the terms of the Sales Agreement, under this prospectus supplement, we may offer and sell ordinary shares having aggregate gross sales proceeds of up to $100,000,000 from time to time through Leerink Partners, acting as our sales agent.

Our ordinary shares are traded on The Nasdaq Global Market, or Nasdaq, and The Nasdaq Iceland Main Market, or Nasdaq Iceland, under the symbol “OCS.” On March 2, 2026, the last sale price of our ordinary shares as reported by Nasdaq was $28.61 per ordinary share. On March 2, 2026, the last sale price of our ordinary shares as reported by Nasdaq Iceland was ISK 3,510.00 per ordinary share.

We are a “foreign private issuer” under applicable Securities and Exchange Commission, or SEC, rules and are eligible for reduced public company disclosure requirements.

Sales of our ordinary shares, if any, under this prospectus supplement and the accompanying base prospectus will be made by any method permitted that is deemed to be an “at the market offering” as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended, or the Securities Act. Leerink Partners is not required to sell any specific number or dollar amount of securities but will act as a sales agent using commercially reasonable efforts consistent with its normal trading and sales practices, on mutually agreed terms between Leerink Partners and us. There is no arrangement for funds to be received in any escrow, trust or similar arrangement.

The compensation to Leerink Partners for sales of ordinary shares sold pursuant to the Sales Agreement will be up to 3.0% of the gross proceeds of any ordinary shares sold under the Sales Agreement. In connection with the sale of the ordinary shares on our behalf, Leerink Partners will be deemed to be an “underwriter” within the meaning of the Securities Act and the compensation of Leerink Partners will be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification and contribution to Leerink Partners with respect to certain liabilities, including liabilities under the Securities Act or the Securities Exchange Act of 1934, as amended, or the Exchange Act. See “Plan of Distribution” beginning on page S-11 for additional information regarding Leerink Partners’ compensation.

INVESTING IN OUR ORDINARY SHARES INVOLVES SIGNIFICANT RISKS. YOU SHOULD REVIEW CAREFULLY THE RISK FACTORS ON PAGE S-4 OF THIS PROSPECTUS SUPPLEMENT AND UNDER SIMILAR HEADINGS IN OTHER DOCUMENTS THAT ARE INCORPORATED BY REFERENCE INTO THIS PROSPECTUS SUPPLEMENT AND THE BASE PROSPECTUS CONCERNING FACTORS YOU SHOULD CONSIDER BEFORE INVESTING IN OUR ORDINARY SHARES.

Neither the SEC nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus supplement. Any representation to the contrary is a criminal offense.

Leerink Partners

The date of this prospectus supplement is March 4, 2026

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement is part of an automatic registration statement that we have filed with the Securities and Exchange Commission, or the SEC, as a “well-known seasoned issuer” as defined in Rule 405 under the Securities Act. Under the shelf registration process, we may offer ordinary shares having an indeterminate aggregate offering price. Under this prospectus supplement, we may offer ordinary shares having aggregate gross sales proceeds of up to $100,000,000 from time to time at prices and on terms to be determined by market conditions at the time of offering. Before buying any of the ordinary shares that we are offering, we urge you to carefully read this prospectus supplement, the accompanying base prospectus, any free writing prospectus that we have authorized for use in connection with this offering, and the information incorporated by reference as described under the headings “Where You Can Find More Information” and “Incorporation by Reference” in this prospectus supplement. These documents contain important information that you should consider when making your investment decision. Generally, when we refer to this “prospectus,” we are referring to the sales agreement prospectus supplement and the accompanying base prospectus combined.

This prospectus supplement describes the terms of this offering of ordinary shares and also adds to and updates information contained in the documents incorporated by reference into the base prospectus. To the extent there is a conflict between the information contained in this prospectus supplement, on the one hand, and the information contained in any document incorporated by reference that was filed with the SEC before the date of this prospectus supplement, on the other hand, you should rely on the information in this prospectus supplement. If any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a document incorporated by reference into this prospectus supplement —the statement in the document having the later date modifies or supersedes the earlier statement.

We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference herein were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

We have not, and Leerink Partners has not, authorized anyone to provide you with information different than or inconsistent with the information contained in or incorporated by reference into this prospectus or in any free writing prospectus that we have authorized for use in connection with this offering. We and Leerink Partners take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. We are not, and Leerink Partners is not, making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus and the documents incorporated by reference into this prospectus, and in any free writing prospectus that we have authorized for use in connection with this offering, is accurate only as of the date of those respective documents, regardless of the time of delivery of those respective documents. Our business, financial condition, results of operations and prospects may have changed since those dates. You should read this prospectus, the documents incorporated by reference into this prospectus, and any free writing prospectus that we have authorized for use in connection with this offering, in their entirety before making an investment decision. You should also read and consider the information in the documents to which we have referred you to in the section of this prospectus supplement titled “Incorporation by Reference.”

We are offering to sell, and seeking offers to buy, ordinary shares only in jurisdictions where offers and sales are permitted. The distribution of this prospectus supplement and the offering of our ordinary shares in certain jurisdictions may be restricted by law. Persons outside the United States who come into possession of this prospectus supplement must inform themselves about, and observe any restrictions relating to, the offering of our ordinary shares and the distribution of this prospectus supplement outside the United States. This prospectus supplement does not constitute, and may not be used in connection with, an offer to sell, or a solicitation of an offer to buy, any securities offered by this prospectus supplement by any person in any jurisdiction in which it is unlawful for such person to make such an offer or solicitation.

RISK FACTORS

An investment in our securities carries a significant degree of risk. Prior to making a decision about investing in our securities, you should carefully consider the specific factors discussed below, together with all of the other information appearing or incorporated by reference in this prospectus supplement. See “Where You Can Find More Information” and “Incorporation by Reference.” You should also consider the risks, uncertainties and assumptions discussed under “Item 3.D-Risk Factors” of our most recent annual report on Form 20-F and reports on Form 6-K we file after the date of this prospectus supplement, that are incorporated herein by reference, as may be amended, supplemented or superseded from time to time by other reports we file with the SEC in the future. The occurrence of one or more of the events or circumstances described in these risk factors, alone or in combination with other events or circumstances, may have a material adverse effect on our business, reputation, revenue, financial condition, results of operations and future prospects, in which event the market price of our securities could decline, and you could lose part or all of your investment. Additional risks and uncertainties of which we are not presently aware or that we currently deem immaterial could also affect our business operations and financial condition. Please also carefully read the section in this prospectus supplement titled “Special Note Regarding Forward-Looking Statements.”

Risks Related to This Offering

We will have broad discretion in the use of the net proceeds from this offering and may not use them effectively.

Our management will have broad discretion in the application of the net proceeds from this offering, including for any of the purposes described in the section titled “Use of Proceeds,” and you will be relying on the judgment of our management regarding the application of these proceeds. You will not have the opportunity, as part of your investment decision, to assess whether the net proceeds are being used effectively. Our management might not apply the net proceeds in ways that ultimately increase or maintain the value of your investment. If we do not invest or apply the net proceeds from this offering in ways that enhance stockholder value, we may fail to achieve expected financial results, which could cause our stock price to decline. In addition, our failure to effectively apply the net proceeds from this offering could have a material adverse effect on our business, results of operations, financial condition and prospects.

If you purchase our ordinary shares in this offering, you will incur immediate and substantial dilution in the net tangible book value of your ordinary shares.

The offering price per ordinary share in this offering may exceed the net tangible book value per ordinary share of our ordinary shares outstanding prior to this offering. The exercise of outstanding options and warrants would result in further dilution of your investment. See the section titled “Dilution” below for a more detailed illustration of the dilution you would incur if you participate in this offering. Because the sales of the ordinary shares offered hereby will be made directly into the market, the prices at which we sell these ordinary shares will vary and these variations may be significant. Purchasers of the ordinary shares we sell, as well as our existing shareholders, will experience significant dilution if we sell ordinary shares at prices significantly below the price at which they invested.

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

In order to raise additional capital, we expect to in the future offer additional 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.

The actual number of ordinary shares we will sell under the Sales Agreement in this offering, 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 an issuance notice to Leerink Partners at any time throughout the term of the offering under this prospectus supplement. The number of ordinary shares that are sold by Leerink Partners after delivering an issuance notice will fluctuate based on the market price of the ordinary shares during the sales period and limits we set with Leerink Partners. Because the price per ordinary share of each ordinary 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 ordinary shares that will be ultimately sold or the gross proceeds to be raised in connection with those sales.

Future sales or issuances of our ordinary shares in the public markets, or the perception of such sales, could depress the trading price of our ordinary shares.

The sale of a substantial number of our ordinary shares or other equity-related securities in the public markets, or the perception that such sales could occur, could depress the market price of our ordinary shares and impair our ability to raise capital through the sale of additional equity securities. We may sell large quantities of our ordinary shares at any time pursuant to this prospectus supplement or in one or more separate offerings. We cannot predict the effect that future sales of ordinary shares or other equity-related securities would have on the market price of our ordinary shares.

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

Investors who purchase ordinary shares in this offering at different times will likely pay different prices, and so may experience different outcomes in their investment results. We will have discretion, subject to market demand, to vary the timing, prices, and numbers of ordinary shares sold, and there is no predetermined minimum or maximum sales price. Investors may experience a decline in the value of their ordinary shares as a result of ordinary share sales made at prices lower than the prices they paid.

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement and the accompanying base prospectus, including the other documents and information incorporated by reference in this prospectus supplement and the base prospectus, contain forward-looking statements, including statements concerning our industry, our operations, our anticipated financial performance and financial condition, and our business plans and growth strategy and product development efforts. These statements constitute forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Exchange Act. Many of the forward-looking statements contained in this prospectus supplement can be identified by the use of forward-looking words such as “anticipate,” “believe,” “could,” “expect,” “should,” “plan,” “intend,” “estimate” and “potential,” among others. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of their dates. These forward-looking statements are based on estimates and assumptions by our management that, although we believe to be reasonable, are inherently uncertain and subject to a number of risks and uncertainties.

The following represent some, but not necessarily all, of the factors that could cause actual results to differ from historical results or those anticipated or predicted by our forward-looking statements:

We have based these forward-looking statements largely on our current expectations and projections about our business, the industry in which we operate and financial trends that we believe may affect our business, financial condition, results of operations and prospects, and these forward-looking statements are not guarantees of future performance or development. These forward-looking statements speak only as of the date of this prospectus supplement and are subject to a number of risks, uncertainties and assumptions described in the section titled “Risk Factors” and elsewhere in this prospectus supplement. Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified, investors should not rely on these forward-looking statements as predictions of future events. The events and circumstances reflected in our forward-looking statements may not be achieved or occur and actual results could differ materially from those projected in the forward-looking statements. Except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements contained herein until after we distribute this prospectus supplement, whether as a result of any new information, future events or otherwise.

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this prospectus supplement, and while we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain, and investors are cautioned not to unduly rely upon these statements.

USE OF PROCEEDS

We may issue and sell ordinary shares having aggregate sales proceeds of up to $100,000,000 from time to time. Because there is no minimum offering price for the ordinary shares that we may offer from time to time, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. There can be no assurance that we will sell any ordinary shares under or fully utilize the Sales Agreement with Leerink Partners as a source of financing.

We currently intend to use any net proceeds from this offering, together with our existing cash, cash equivalents and short-term financial assets, for pipeline development, general corporate purposes and working capital.

The amounts and timing of our actual expenditures will depend on numerous factors, including our development efforts with respect to our product candidates, as well as the amount of cash used in our operations. We therefore cannot estimate with certainty the amount of net proceeds to be used for the purposes described above. We may find it necessary or advisable to use the net proceeds for other purposes, and we will have broad discretion in the application of the net proceeds. Pending these uses, we intend to invest any net proceeds in short- and intermediate-term, interest-bearing obligations, investment-grade instruments, certificates of deposit or direct or guaranteed obligations.

DILUTION

If you invest in our ordinary shares, your interest will be diluted to the extent of the difference between the price per ordinary share of our ordinary shares you pay in this offering and the as adjusted net tangible book value per ordinary share of our ordinary shares immediately after this offering.

Our net tangible book value as of December 31, 2025 was CHF 182.8 million ($230.6 million), or CHF 3.15 ($3.98) per ordinary share. Net tangible book value per ordinary share represents the amount of our total assets, less our intangible assets and our total liabilities, divided by the number of ordinary shares outstanding as of December 31, 2025.

After giving effect to the sale of ordinary shares in the aggregate amount of $100 million pursuant to this prospectus supplement at an assumed offering price of $28.61 per ordinary share, the last reported sale price of our ordinary shares as reported by Nasdaq on March 2, 2026, and after deducting the sales commissions and estimated offering expenses payable by us, our as adjusted net tangible book value as of December 31, 2025, would have been CHF 258.5 million ($326.0 million), or CHF 4.20 ($5.30) per ordinary share. This represents an immediate increase in net tangible book value above the net tangible book value of CHF 1.05 ($1.32) per ordinary share to our existing shareholders and an immediate dilution in net tangible book value of CHF 18.48 ($23.31) per ordinary share to investors purchasing ordinary shares in this offering.

The following table illustrates this dilution 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 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.

Swiss Franc amounts have been translated into U.S. dollars at the exchange rate in effect on December 31, 2025. Such U.S. dollar amounts are not necessarily indicative of the amounts of U.S. dollars that could actually have been purchased upon exchange of Swiss Francs on December 31, 2025 and have been provided solely for the convenience of the reader. The ordinary shares subject to the Sales Agreement are being sold from time to time at various prices. This information is supplied for illustrative purposes only and may differ based on the actual offering price and the actual number of ordinary shares offered.

The foregoing table and calculations are based on 57,984,438 ordinary shares outstanding as of December 31, 2025 and excludes:

To the extent that outstanding options and warrants are exercised or new options are issued under the 2023 Plan, investors purchasing our ordinary shares in this offering will experience further dilution. In addition, 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 we raise additional capital through the sale of equity or convertible debt securities, the issuance of these securities could result in further dilution to our shareholders.

PLAN OF DISTRIBUTION

We have entered into an amended and restated Sales Agreement with Leerink Partners under which we may issue and sell shares of our ordinary shares having aggregate gross sales proceeds of up to $100,000,000 of our ordinary shares from time to time through or to Leerink Partners acting as our sales agent or principal.

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

We will pay Leerink Partners commissions, in cash, for its services in acting as agent in the sale of our ordinary shares. Leerink Partners will be entitled to compensation at a fixed commission rate equal to up to 3.0% of the gross proceeds from the sales of any ordinary shares sold pursuant to the Sales Agreement. Because there is no minimum offering amount required as a condition to close this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. Pursuant to the terms of the Sales Agreement, we have also agreed to reimburse Leerink Partners for certain specified expenses, including the fees and disbursements of its legal counsel and FINRA counsel fees in an amount not to exceed $55,000.

Additionally, pursuant to the terms of the Sales Agreement, we agreed to reimburse Leerink Partners for the reasonable and documented fees and costs of its legal counsel reasonably incurred in connection with Leerink Partners’ ongoing diligence arising from the transactions contemplated by the Sales Agreement in an amount not to exceed $25,000 per calendar quarter. We estimate that total expenses for the offering excluding compensation payable to Leerink Partners under the terms of the Sales Agreement will be approximately $1,500,000.

Settlement for sales of our ordinary shares will occur on the second trading day following the date on which any sales are made, or on some other date that is agreed upon by us and Leerink Partners in connection with a particular transaction, in return for payment of the net proceeds to us. Settlement for any securities offered under this prospectus supplement may occur on the first business day that is also a trading day following the date on which any sales were made 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 Leerink Partners may agree upon. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

Leerink Partners will use its commercially reasonable efforts, consistent with its normal 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 shares of ordinary shares on our behalf, Leerink Partners will be deemed to be an “underwriter” within the meaning of the Securities Act and the compensation of Leerink Partners will be deemed to be underwriting commissions or discounts. We have agreed to provide indemnification and contribution to Leerink Partners against certain civil liabilities, including liabilities under the Securities Act.

Leerink Partners and/or its affiliates have provided, and may in the future provide, various investment banking and other financial services for us for which services they have received and, may in the future receive, customary fees. In the course of its business, Leerink Partners may actively trade our securities for its own account or for the accounts of customers, and, accordingly, Leerink Partners may at any time hold long or short positions in such securities.

This offering of our ordinary shares pursuant to Sales Agreement will terminate upon the earlier of (1) sale of all of our ordinary shares subject to this prospectus supplement or (2) the termination of the Sales Agreement as permitted therein. We and Leerink Partners may each terminate the Sales Agreement at any time upon prior written notice.

Any portion of the ordinary shares included in this prospectus supplement that are not previously sold or included in an active placement notice pursuant to the Sales Agreement are available for sale in other offerings pursuant to our registration statement, of which this prospectus supplement forms a part, and the accompanying base prospectus.

Our ordinary shares are listed and traded on The Nasdaq Global Market and The Nasdaq Iceland Main Market under the symbol “OCS.” The transfer agent and registrar of our ordinary shares is Continental Stock Transfer & Trust Company.

MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS FOR U.S. HOLDERS

The following is a discussion of certain material U.S. federal income tax considerations generally applicable to the acquisition, ownership, and disposition of ordinary shares by a “U.S. Holder.” This discussion applies only to ordinary shares that are held by a U.S. Holder as “capital assets” within the meaning of Section 1221 of the Internal Revenue Code of 1986, as amended, or the Code (generally, property held for investment). This discussion does not describe all U.S. federal income tax considerations that may be relevant to a U.S. Holder in light of such U.S. Holder’s particular circumstances, nor does it address any state, local, or non-U.S. tax considerations, any non-income tax (such as gift or estate tax) considerations, any minimum tax provisions of the Code, the special tax accounting rules under Section 451(b) of the Code, the Medicare contribution tax on net investment income, or any tax consequences that may be relevant to U.S. Holders that are subject to special tax rules, including, without limitation:

If a partnership (including an entity or arrangement treated as a partnership for U.S. federal income tax purposes) holds ordinary shares, the tax treatment of a partner in such partnership generally will depend on the status of the

partner and the activities of the partnership and the partner. Partnerships holding ordinary shares should consult their tax advisors regarding the tax consequences in their particular circumstances.

This discussion is based on the Code, the U.S. Treasury regulations promulgated thereunder, administrative rulings, and judicial decisions, all as currently in effect and all of which are subject to change or differing interpretation, possibly with retroactive effect. Any such change or differing interpretation could alter the tax consequences described herein. Furthermore, there can be no assurance that the Internal Revenue Service (the “IRS”) will not challenge the tax considerations described herein and that a court will not sustain such challenge.

For purposes of this discussion, a “U.S. Holder” is a beneficial owner of ordinary shares, that is, for U.S. federal income tax purposes:

THIS DISCUSSION IS FOR GENERAL INFORMATIONAL PURPOSES ONLY AND IS NOT TAX ADVICE. U.S. HOLDERS SHOULD CONSULT THEIR TAX ADVISORS REGARDING THE TAX CONSEQUENCES OF THE ACQUISTION, OWNERSHIP, AND DISPOSITION OF ORDINARY SHARES IN THEIR PARTICULAR CIRCUMSTANCES.

Distributions on Ordinary Shares

Subject to the “passive foreign investment company,” or PFIC, rules discussed below under “—Passive Foreign Investment Company Rules,” distributions on ordinary shares generally will be taxable as dividends for U.S. federal income tax purposes to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. Such distributions in excess of our current and accumulated earnings and profits will constitute a return of capital that will be applied against and reduce (but not below zero) the applicable U.S. Holder’s adjusted tax basis in its ordinary shares. Any remaining excess will be treated as gain realized on the sale or other taxable disposition of ordinary shares and will be treated as described below under “—Sale or Other Taxable Disposition of Ordinary Shares.” The amount of any such distributions will include any amounts required to be withheld by us (or another applicable withholding agent) in respect of any non-U.S. taxes. Any such amount treated as a dividend will be treated as foreign-source dividend income. Any such dividends received by a corporate U.S. Holder generally will not qualify for the dividends-received deduction generally allowed to U.S. corporations in respect of dividends received from other U.S. corporations. With respect to non-corporate U.S. Holders, any such dividends generally will be taxed at currently preferential long-term capital gains rates only if (i) ordinary shares are readily tradable on an established securities market in the United States or we are eligible for benefits under an applicable tax treaty with the United States, (ii) we are not treated as a PFIC with respect to the applicable U.S. Holder at the time the dividend was paid or in the preceding year, and (iii) certain holding period and other requirements are met. The amount of any such dividends paid in a currency other than the U.S. dollar generally will be the U.S. dollar amount calculated by reference to the exchange rate in effect on the date of actual or constructive receipt, regardless of whether the payment is in fact converted into U.S. dollars at that time. A U.S. Holder may have foreign currency gain or loss if the dividend is converted into U.S. dollars after the date of actual or constructive receipt.

As noted above and subject to applicable limitations, taxing jurisdictions other than the United States may withhold taxes from distributions on ordinary shares, and a U.S. Holder may be eligible for a reduced rate of withholding to the extent there is an applicable tax treaty between the applicable taxing jurisdiction and the United States and/or may be eligible for a foreign tax credit against the U.S. Holder’s U.S. federal income tax liability.

Recently issued U.S. Treasury regulations may in some circumstances prohibit a U.S. Holder from claiming a foreign tax credit with respect to certain foreign taxes that are not creditable under applicable tax treaties. However, the IRS has released notices that provide relief from certain of the provisions of the Treasury Regulations described above for taxable years ending before the date that a notice or other guidance withdrawing or modifying the temporary relief is issued (or any later date specified in such notice or other guidance). In lieu of claiming a foreign tax credit, a U.S. Holder may, at such U.S. Holder’s election, deduct foreign taxes in computing such U.S. Holder’s taxable income, subject to generally applicable limitations under U.S. tax law. An election to deduct foreign taxes in lieu of claiming a foreign tax credit applies to all foreign taxes paid or accrued in the taxable year in which such election is made. The foreign tax credit rules are complex and U.S. Holders should consult their tax advisers regarding the application of such rules, including the creditability of foreign taxes, in their particular circumstances.

Sale or Other Taxable Disposition of Ordinary Shares

Subject to the PFIC rules discussed below under “—Passive Foreign Investment Company Rules,” upon any sale or other taxable disposition of ordinary shares, a U.S. Holder generally will recognize gain or loss in an amount equal to the difference, if any, between (i) the sum of (A) the amount of cash and (B) the fair market value of any other property received in such sale or disposition and (ii) the U.S. Holder’s adjusted tax basis in the ordinary shares. Any such gain or loss generally will be capital gain or loss and will be long-term capital gain or loss if the U.S. Holder’s holding period for such ordinary shares exceeds one year. Long-term capital gain recognized by non-corporate U.S. Holders generally will be taxed at currently preferential long-term capital gains rates. The deductibility of capital losses is subject to limitations. For foreign tax credit purposes, any such gain or loss generally will be treated as U.S. source gain or loss.

If the consideration received by a U.S. Holder upon a sale or other taxable disposition of ordinary shares is not paid in U.S. dollars, the amount realized will be the U.S. dollar value of such payment calculated by reference to the exchange rate in effect on the date of such sale or disposition. A U.S. Holder may have foreign currency gain or loss to the extent of the difference, if any, between (i) the U.S. dollar value of such payment on the date of such sale or disposition and (ii) the U.S. dollar value of such payment calculated by reference to the exchange rate in effect on the date of settlement.

U.S. Holders should consult their tax advisors regarding the tax consequences of a sale or other taxable disposition of ordinary shares, including the creditability of foreign taxes imposed on such sale or disposition by a taxing jurisdiction other than the United States, in their particular circumstances.

Passive Foreign Investment Company Rules

The U.S. federal income tax treatment of U.S. Holders could be materially different from that described above if we are treated as a PFIC for U.S. federal income tax purposes. A non-U.S. corporation generally will be treated as a PFIC for U.S. federal income tax purposes if either (i) at least 75% of its gross income in a taxable year, including its pro rata share of the gross income of any corporation in which it is considered to own at least 25% of the shares by value, is passive income, or (ii) at least 50% of its assets in a taxable year (ordinarily determined based on fair market value and averaged quarterly over the year), including its pro rata share of the assets of any corporation in which it is considered to own at least 25% of the shares by value, are held for the production of, or produce, passive income. Passive income generally includes dividends, interest, rents and royalties (other than rents or royalties derived from the active conduct of a trade or business), and gains from the disposition of passive assets.

Based on our analysis of our income, assets, activities, and market capitalization, we believe that we were not a PFIC for our taxable year ended December 31, 2025. The determination of whether a non-U.S. corporation is a PFIC is a fact-intensive determination made on an annual basis and the applicable law is subject to varying interpretation. In particular, the characterization of our assets as active or passive may depend in part on our current and intended future business plans, which are subject to change. The amount of passive income and passive assets we take into account for PFIC testing purposes depends, in part, on the size of our cash balance (taking into account the timing and manner in which such cash is used) and the interest rates applicable thereto. In addition, the total value of our assets for PFIC testing purposes may be determined in part by reference to our market capitalization from time to time, which may fluctuate considerably. As a result, there can be no assurance with respect to our status as a PFIC for any taxable year, and our U.S. counsel expresses no opinion with respect to our PFIC status for the taxable year ended December

31, 2025, the taxable year ending December 31, 2026, or for future taxable years. Even if we determine that we are not a PFIC for a taxable year, there can be no assurance that the IRS will agree with that conclusion and that the IRS would not successfully challenge our position. U.S. Holders of ordinary shares should be aware of the risk that we may become a PFIC and should review the section and consult their tax advisors concerning the application of the PFIC rules to the ordinary shares in their particular circumstances.

Although PFIC status is generally determined annually, if we are determined to be a PFIC for any taxable year (or portion thereof) that is included in the holding period of a U.S. Holder in its ordinary shares and the U.S. Holder did not make either a mark-to-market election or a qualified electing fund, or QEF, election, which are referred to collectively as the “PFIC Elections” for purposes of this discussion, for the first taxable year in which we are treated as a PFIC, and in which the U.S. Holder held (or was deemed to hold) ordinary shares, or the U.S.

Holder does not otherwise make a purging election, as described below, the U.S. Holder generally will be subject to special and adverse rules with respect to (i) any gain recognized by the U.S. Holder on the sale or other taxable disposition of its ordinary shares and (ii) any “excess distribution” made to the U.S. Holder (generally, any distributions to the U.S. Holder during a taxable year of the U.S. Holder that are greater than 125% of the average annual distributions received by the U.S. Holder in respect of its ordinary shares during the three preceding taxable years of the U.S. Holder or, if shorter, the U.S. Holder’s holding period in its ordinary shares).

Under these rules:

PFIC Elections

If we are treated as a PFIC and ordinary shares constitute “marketable stock,” a U.S. Holder may avoid the adverse PFIC tax consequences discussed above if such U.S. Holder makes a mark-to-market election with respect to its ordinary shares for the first taxable year in which the U.S. Holder holds (or is deemed to hold) ordinary shares and each subsequent taxable year. Such U.S. Holder generally will include for each of its taxable years as ordinary income the excess, if any, of the fair market value of its ordinary shares at the end of such year over its adjusted tax basis in its ordinary shares. The U.S. Holder also will recognize an ordinary loss in respect of the excess, if any, of its adjusted tax basis in its ordinary shares over the fair market value of its ordinary shares at the end of its taxable year (but only to the extent of the net amount of previously included income as a result of the mark-to-market election). The U.S. Holder’s adjusted tax basis in its ordinary shares will be adjusted to reflect any such income or loss amounts, and any further gain recognized on a sale or other taxable disposition of its ordinary shares will be treated as ordinary income.

The mark-to-market election is available only for “marketable stock,” generally, stock that is regularly traded on a national securities exchange that is registered with the SEC, including the Nasdaq (on which ordinary shares are currently listed), or on a foreign exchange or market that the IRS determines has rules sufficient to ensure that the market price represents a legitimate and sound fair market value. As such, such election generally will not apply to any of our non-U.S. subsidiaries, unless the shares in such subsidiaries are themselves “marketable stock.” As such, U.S. Holders may continue to be subject to the adverse PFIC tax consequences discussed above with respect to any lower-tier PFICs, as discussed below, notwithstanding their mark-to-market election with respect to ordinary shares.

If made, a mark-to-market election would be effective for the taxable year for which the election was made and for all subsequent taxable years unless ordinary shares cease to qualify as “marketable stock” for purposes of the PFIC rules or the IRS consents to the revocation of the election. U.S. Holders should consult their tax advisors regarding the availability and tax consequences of a mark-to-market election with respect to ordinary shares in their particular circumstances.

If we are treated as a PFIC, a U.S. Holder may also avoid the adverse PFIC tax consequences discussed above with respect to ordinary shares if the U.S. Holder makes a valid QEF election for the first taxable year in which the U.S. Holder owns (or is treated as owning) ordinary shares.

If a U.S. Holder has made a QEF election with respect to ordinary shares, and the special tax and interest charge rules do not apply to such shares (because the QEF election was made in the U.S. Holder’s first taxable year in which the U.S. Holder owns (or is treated as owning) ordinary shares or a purging election was made, as described below), any gain recognized on the sale of ordinary shares will generally be taxable as capital gain and no interest charge will be imposed under the PFIC rules. A U.S. Holder that makes a QEF election with respect to ordinary shares is currently taxed on its pro rata share of our earnings and profits, whether or not distributed. In such case, a subsequent distribution of such earnings and profits that were previously included in income generally should not be taxable as a dividend to the U.S. Holder. The U.S. Holder’s tax basis in ordinary shares with respect to which a QEF election has been made will be increased by amounts that are included in income, and decreased by amounts distributed but not taxed as dividends, under the above rules. Similar basis adjustments apply to property if by reason of holding such property the U.S. Holder is treated under the applicable attribution rules as owning ordinary shares with respect to which a QEF election has been made. A U.S. Holder generally can make a separate election to defer the payment of taxes on undistributed income inclusions under the QEF election rules, but if deferred, any such taxes will be subject to an interest charge.

In order to comply with the requirements of a QEF election with respect to ordinary shares, a U.S. Holder generally must receive a PFIC Annual Information Statement (as defined in Treasury Regulations Section 1.1295-1(g)) from us. If we are determined to be a PFIC for any taxable year, we will endeavor to make available to U.S. Holders a PFIC Annual Information Statement with respect to such taxable year. However, there is no assurance that we will have timely knowledge of our status as a PFIC in the future or that we will make available a PFIC Annual Information Statement. U.S. Holders are urged to consult their tax advisors regarding the availability and tax consequences of a QEF election with respect to ordinary shares in their particular circumstances.

If we are treated as a PFIC and a U.S. Holder failed or was unable to timely make a PFIC Election for prior periods, the U.S. Holder might seek to make a purging election to rid its ordinary shares of the PFIC taint. Under the purging election, the U.S. Holder will be deemed to have sold its ordinary shares at their fair market value and any gain recognized on such deemed sale will be treated as an excess distribution, as described above. As a result of the purging election, the U.S. Holder will have a new adjusted tax basis and holding period in ordinary shares solely for purposes of the PFIC rules.

Related PFIC Rules

If we are treated as a PFIC and, at any time, have a non-U.S. subsidiary that is treated as a PFIC, a U.S. Holder generally would be deemed to own a proportionate amount of the shares of such lower-tier PFIC, and generally could incur liability for the deferred tax and interest charge described above if we receive a distribution from, or sell or otherwise dispose of all or part of our interest in, such lower-tier PFIC, or the U.S. Holder otherwise was deemed to have sold or otherwise disposed of an interest in such lower-tier PFIC. U.S. Holders should consult their tax advisors regarding the application of the lower-tier PFIC rules in their particular circumstances.

A U.S. Holder that owns (or is deemed to own) shares in a PFIC during any taxable year may have to file an IRS Form 8621 (whether or not a QEF election or a mark-to-market election is made) and to provide such other information as may be required by the U.S. Treasury Department. Failure to do so, if required, will extend the statute of limitations applicable to such U.S. Holder until such required information is furnished to the IRS and could result in penalties.

THE PFIC RULES ARE VERY COMPLEX. U.S. HOLDERS SHOULD CONSULT THEIR TAX ADVISORS REGARDING THE APPLICATION OF SUCH RULES IN THEIR PARTICULAR CIRCUMSTANCES.

Information Reporting and Backup Withholding

Payments of dividends and sales proceeds that are made within the United States or through certain U.S.-related financial intermediaries are subject to information reporting, and may be subject to backup withholding, unless (i) the U.S. Holder is a corporation or other exempt recipient or (ii) in the case of backup withholding, the U.S. Holder provides a correct taxpayer identification number and certifies that it is not subject to backup withholding.

Backup withholding is not an additional tax. The amount of any backup withholding from a payment to a U.S. Holder will be allowed as a credit against the U.S. Holder’s U.S. federal income tax liability and may entitle the U.S. Holder to a refund, provided that the required information is timely furnished to the IRS.

U.S. Holders should consult their tax advisors regarding the information reporting requirements and the application of the backup withholding rules in their particular circumstances.

THIS DISCUSSION IS FOR GENERAL INFORMATIONAL PURPOSES ONLY AND IS NOT TAX ADVICE. U.S. HOLDERS SHOULD CONSULT THEIR TAX ADVISORS REGARDING THE U.S. FEDERAL, STATE, AND LOCAL AND NON-U.S. INCOME AND NON-INCOME TAX CONSEQUENCES OF THE ACQUISITION, OWNERSHIP, AND DISPOSITION OF ORDINARY SHARES, INCLUDING THE IMPACT OF ANY POTENTIAL CHANGE IN LAW, IN THEIR PARTICULAR CIRCUMSTANCES.

MATERIAL SWISS INCOME TAX IMPLICATIONS

Please see the section entitled “Item 10. Additional Information – E. Taxation - Material Swiss Tax Considerations” incorporated by reference from our Annual Report, as well as any amendments thereto reflected in our subsequent filings with the SEC.

DIVIDEND POLICY

We have not paid any cash dividends on the Ordinary Shares to date and do not intend to pay cash dividends for the foreseeable future. Dividends may be paid only if we have sufficient distributable profit from previous years or sufficient free reserves to allow the distribution of a dividend. Swiss law requires that we retain at least 5% of our annual net profit as general reserves for so long as these reserves amount to less than 20% of our paid-in nominal share capital.

LEGAL MATTERS

The validity of the securities offered hereby on behalf of Oculis Holding AG and certain other matters of Swiss law will be passed upon for us by VISCHER AG, Basel, Switzerland. Certain matters of U.S. federal law will be passed upon for us by Cooley LLP, New York, New York. Leerink Partners LLC is being represented in connection with this offering by Davis Polk & Wardwell LLP, New York, New York.

EXPERTS

The financial statements and management’s assessment of the effectiveness of internal control over financial reporting (which is included in Management’s report on internal control over financial reporting) incorporated in this prospectus supplement by reference to the Annual Report on Form 20-F for the year ended December 31, 2025 have been so incorporated in reliance on the report of PricewaterhouseCoopers SA, an independent registered accounting firm, given on the authority of said firm as experts in auditing and accounting. PricewaterhouseCoopers SA is a member of EXPERTsuisse — Swiss Expert Association for Audit, Tax and Fiduciary.

WHERE YOU CAN FIND MORE INFORMATION

We file annual reports on Form 20-F and current reports on Form 6-K and other information from time to time with the SEC in accordance with such requirements. Our SEC filings are available to the public on the internet at a website maintained by the SEC located at www.sec.gov. We also maintain a website at www.oculis.com. The information contained on, or that can be accessible through, our website is not a part of this prospectus supplement and the inclusion of our website address in this prospectus supplement is an inactive textual reference only.

This prospectus supplement is part of a registration statement that we filed with the SEC and does not contain all of the information in the registration statement. You should review the information and exhibits in the registration statement for further information on us and the securities that we are offering. Statements in this prospectus supplement about these documents are summaries and each statement is qualified in all respects by reference to the document to which it refers. You should read the actual documents for a more complete description of the relevant matters.

INCORPORATION BY REFERENCE

The SEC allows us to incorporate by reference much of the information that we file with the SEC, which means that we can disclose important information to you by referring you to those publicly available documents. The information that we incorporate by reference in this prospectus supplement is considered to be 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 Exchange Act (in each case, other than those documents or the portions of those documents furnished, rather than filed, and, except as may be noted in any such Form 6-K, exhibits filed on such form that are related to such information), until the offering of the securities under the registration statement of which this prospectus supplement forms a part is terminated or completed:

You can obtain any of the filings incorporated by reference in this prospectus supplement through us or from the SEC through the SEC’s website at www.sec.gov. Our filings with the SEC, including our annual reports on Form 20-F and reports on Form 6-K and exhibits incorporated in and amendments to those reports, are also available free of charge on our website (www.oculis.com) as soon as reasonably practicable after they are filed with, or furnished to, the SEC. The reference to our website is an inactive textual reference only, and information contained therein or connected thereto is not incorporated into this prospectus supplement or the registration statement of which it forms a part. We will provide to each person, including any beneficial owner, to whom this prospectus supplement is delivered, a copy of any or all the reports or documents incorporated by reference in this prospectus supplement at no cost, upon written or oral request to us at the following address and telephone number:

Oculis Holding AG
Bahnhofstrasse 20
CH-6300
Zug, Switzerland
Attn: Investor Relations
+41 41 711 39 60

Oculis Holding AG

Up to $100,000,000

Ordinary Shares

PROSPECTUS SUPPLEMENT

Leerink Partners

March 4, 2026

PART II
INFORMATION NOT REQUIRED IN PROSPECTUS

Item 8. Indemnification of Board of Directors and Executive Committee

Under Swiss corporate law, an indemnification by the corporation of a director or member of the executive committee in relation to potential personal liability is not effective to the extent the director or member of the executive committee intentionally or grossly negligently violated his or her corporate duties towards the corporation. Furthermore, the general meeting of shareholders may discharge the directors and members of the executive committee from liability for their conduct to the extent the respective facts are known to shareholders. Such discharge is effective only with respect to claims of the company and of those shareholders who approved the discharge or who have since acquired their shares in full knowledge of the discharge. Most violations of corporate law are regarded as violations of duties towards the corporation rather than towards the shareholders. In addition, indemnification of other controlling persons is not permitted under Swiss corporate law, including shareholders of the corporation.

Our Articles of Association provide for indemnification of the existing and former members of the board of directors or the executive committee against liabilities arising in connection with the performance of their duties in such capacity. In addition, under general principles of Swiss employment law, an employer may be required to indemnify an employee against losses and expenses incurred by such employee in the proper execution of his or her duties under the employment agreement with the employer.

We have entered into indemnification agreements with each of the members of our board of directors and executive officers, the form of which has been filed as an exhibit to our annual report on Form 20-F filed with the Securities and Exchange Commission.

Item 9. Exhibits

* To be subsequently filed, if applicable, by an amendment to this registration statement or by a Report on Form 6-K.

** To be filed, if applicable, in accordance with the requirements of Section 305(b)(2) of the Trust Indenture Act of 1939 and Rule 5b-3 thereunder.

Item 10. Undertakings

(a) The undersigned registrant hereby undertakes:

(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i) To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;

(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the SEC pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than 20% change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement; and

(iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement; provided, however, that paragraphs (a)(1)(i), (a)(1)(ii) and (a)(1)(iii) of this section do not apply if the registration statement is on Form F-3 and information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the SEC by the registrant pursuant to section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

(2) That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

(4) To file a post-effective amendment to the registration statement to include any financial statements required by Item 8.A. of Form 20-F at the start of any delayed offering or throughout a continuous offering. Financial statements and information otherwise required by Section 10(a)(3) of the Act need not be furnished, provided, that the registrant includes in the prospectus, by means of a post-effective amendment, financial statements required pursuant to this paragraph (a)(4) and other information necessary to ensure that all other information in the prospectus is at least as current as the date of those financial statements. Notwithstanding the foregoing, with respect to registration

statements on Form F-3, a post-effective amendment need not be filed to include financial statements and information required by Section 10(a)(3) of the Act or Item 8.A of Form 20-F if such financial statements and information are contained in periodic reports filed with or furnished to the Commission by the registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the Form F-3.

(5) That, for the purpose of determining liability under the Securities Act of 1933 to any purchaser:

(i) If the registrant is relying on Rule 430B:

(A) Each prospectus filed by the registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

(B) Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5) or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii) or (x) for the purpose of providing the information required by Section 10(a) of the Securities Act of 1933 shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date; or

(6) That, for the purpose of determining liability of the registrant under the Securities Act of 1933 to any purchaser in the initial distribution of the securities, the undersigned registrant undertakes that in a primary offering of securities of the undersigned registrant pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

(i) Any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424;

(ii) Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;

(iii) The portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by or on behalf of the undersigned registrant; and

(iv) Any other communication that is an offer in the offering made by the undersigned registrant to the purchaser.

(b) The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the registrant’s annual report pursuant to Section 13(a) or Section 15(d)

of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to Section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(c) Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act of 1933 and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding), is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act of 1933 and will be governed by the final adjudication of such issue.

(d) To file an application for the purpose of determining the eligibility of the trustee to act under subsection (a) of Section 310 of the Trust Indenture Act of 1939, or the Act, in accordance with the rules and regulations prescribed by the Commission under Section 305(b)(2) of the Act.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form F-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in Lausanne, Switzerland, on March 4, 2026.

OCULIS HOLDING AG

By: /s/ Riad Sherif

Riad Sherif

Chief Executive Officer

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints Riad Sherif and Sylvia Cheung, and each of them acting individually, as his or her true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for him or her and in his or her name, place and stead, in any and all capacities, to sign any and all amendments to this registration statement, including post-effective amendments, and registration statements filed pursuant to Rule 462 under the Securities Act, and to file the same, with all exhibits thereto, and all other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorney-in-fact and agent and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith and about the premises, as fully for all intents and purposes as they, he or she might or could do in person, hereby ratifying and confirming all that said attorney-in-fact and agent or any of them, or their, his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed by the following persons in the capacities and on the dates indicated:

SIGNATURE OF AUTHORIZED REPRESENTATIVE IN THE UNITED STATES

Pursuant to the requirements of the Securities Act of 1933, as amended, the undersigned has signed this registration statement, solely in the capacity as the duly authorized representative of the Registrant, in Boston, Massachusetts, on March 4, 2026.

OCULIS US INC

By: /s/ Sylvia Cheung

Sylvia Cheung

Chief Financial Officer