As filed with the Securities and Exchange Commission on April 1, 2025

Registration No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM S-3

REGISTRATION STATEMENT
UNDER THE SECURITIES ACT OF 1933

GCT Semiconductor Holding, Inc.

(Exact name of registrant as specified in its charter)

2290 North 1st Street, Suite 201

San Jose, California 95131
(408) 434-6040

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

John Schlaefer

Chief Executive Officer

GCT Semiconductor Holding, Inc.

2290 North 1st Street, Suite 201

San Jose, California 95131

(408) 434-6040

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

Copies to:

Albert Lung, Esq.

Morgan, Lewis & Bockius LLP

1400 Page Mill Road

Palo Alto, CA 94304

(650) 843-4000

Approximate date of commencement of proposed sale to the public:

From time to time after this registration statement becomes effective.

If the 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, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box. x

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.D. or a post-effective amendment thereto that shall become effective upon filing with 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.D. filed to register additional securities or classes of additional securities pursuant to Rule 413(b) under the Securities Act, check the following box. ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

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 registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the registration statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

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 sales agreement prospectus immediately follows the base prospectus. Upon termination of the sales agreement with B. Riley Securities, Inc. and H.C. Wainwright & Co., LLC as sales agents, any portion of the $75,000,000 of securities included in the sales agreement prospectus that remains unsold pursuant to the sales agreement will be available for sale in other offerings pursuant to the base prospectus and a corresponding prospectus supplement, and if no shares are sold under the sales agreement, the full $75,000,000 of securities not sold may be sold in other offerings pursuant to the base prospectus and a corresponding prospectus supplement.

TABLE OF CONTENTS

The distribution of this prospectus and sale of these securities in certain jurisdictions may be restricted. Persons in possession of this prospectus are required to inform themselves about and observe any such restrictions. We are not making an offer of these securities in any jurisdiction where the offer is not permitted.

All references in this prospectus to “we,” “us,” “our,” and “GCT” refer only to GCT Semiconductor Holding, Inc. and not to any existing or future subsidiaries of GCT Semiconductor Holding, Inc., unless the context otherwise requires.

ABOUT THIS PROSPECTUS

This document is called a prospectus and is part of a registration statement on Form S-3 that we filed with the SEC using a “shelf” registration process. Under this shelf process, we may offer and sell, from time to time in one or more offerings, the securities described in this prospectus. This prospectus provides you with a general description of the securities we may offer and the general manner in which these securities may be offered. Each time we sell securities under this prospectus, we will provide you with a prospectus supplement that will contain specific information about the terms of that offering and the offered securities. That prospectus supplement may also supplement, update or amend information contained in or incorporated by reference into this prospectus.

The registration statement of which this prospectus is a part contains additional information about us and the securities we may offer by this prospectus. Specifically, we have filed and incorporated by reference certain legal documents that control the terms of the securities offered by this prospectus as exhibits to the registration statement. We will file or incorporate by reference certain other legal documents that will control the terms of the securities we may offer by this prospectus as exhibits to the registration statement or to reports we file with the SEC that are incorporated by reference into this prospectus.

In addition, we may prepare and deliver one or more “free writing prospectuses” to you in connection with any offering of securities under this prospectus. Any such free writing prospectus may contain additional information about us, our business, the offered securities, the manner in which such securities are being offered, our intended use of the proceeds from the sale of such securities, risks relating to our business or an investment in such securities or other information.

This prospectus and certain of the documents incorporated by reference into this prospectus contain, and any accompanying prospectus supplement or free writing prospectus that we deliver to you may contain, summaries of information contained in documents that we have filed or will file as exhibits to our SEC filings. Such summaries do not purport to be complete and are subject to, and qualified in their entirety by reference to, the actual documents filed with the SEC.

Copies of the registration statement of which this prospectus is a part and of the documents incorporated by reference into this prospectus may be obtained as described below under the heading “Documents Incorporated by Reference” and under the heading “Where You Can Find More Information.”

You should not assume that the information contained in this prospectus, the registration statement to which this prospectus is a part, any accompanying prospectus supplement or any free writing prospectus that we deliver to you is accurate as of any date other than the date of such documents or that the information incorporated by reference into this prospectus is accurate as of any date other than the date of the document incorporated by reference. Our business, operating results, financial condition, capital resources and prospects may have changed since that date.

You should rely only on the information contained in or incorporated by reference into this prospectus, the registration statement of which this prospectus is a part, any accompanying prospectus supplement, and any free writing prospectus that we deliver to you. We have not authorized anyone to provide you with different information. If you receive any other information, you should not rely on it.

RISK FACTORS

Investing in our securities involves risks. Before investing in our securities, you should carefully consider the specific risks set forth under the caption “Risk Factors” in our filings with the Securities and Exchange Commission (which we refer to as the “SEC”) that are incorporated by reference into this prospectus and under the caption “Risk Factors” in any accompanying prospectus supplement or free writing prospectus that we deliver to you. You should also carefully consider all other information contained in or incorporated by reference into this prospectus or in any accompanying prospectus supplement or free writing prospectus that we deliver to you. A discussion of the documents incorporated by reference into this prospectus is set forth below under the heading “Documents Incorporated by Reference.”

WHERE YOU CAN FIND MORE INFORMATION

We are subject to certain information reporting requirements of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and, in accordance with these requirements, we file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to you at the SEC’s website at http://www.sec.gov and our website at https://investors.gctsemi.com/sec-filings. The information contained in, or that can be accessed through, our website is not a part of this prospectus or any accompanying prospectus supplement.

We have filed with the SEC a registration statement on Form S-3 relating to the securities offered by this prospectus. This prospectus is a part of that registration statement, which includes additional information about us and the securities offered by this prospectus. You may review and obtain a copy of the registration statement and the exhibits that are a part of the registration statement through the SEC’s website or our website. You can also call or write us for a copy as described below under “Documents Incorporated by Reference.”

DOCUMENTS INCORPORATED BY REFERENCE

The SEC allows us to “incorporate by reference” the information we file with the SEC under the Exchange Act, which means that we can disclose important information to you by referring you to those documents. Information incorporated by reference is considered to be a part of this prospectus, and information that we file later with the SEC will automatically update, modify and, where applicable, supersede this information. We incorporate by reference into this prospectus the specific documents listed below and all documents filed by us with the SEC pursuant to Section 13(a), 13(c), 14, or 15(d) of the Exchange Act between the date of this prospectus and the termination of the offering of securities under this prospectus (other than, in each case, documents or information deemed to be furnished and not filed in accordance with SEC rules), which future filings shall be deemed to be incorporated by reference into this prospectus and to be part of this prospectus from the date we subsequently file such documents. The SEC file number for these documents is 1-41013.

Any statement contained in this prospectus or in any document incorporated by reference into this prospectus shall be deemed to be modified or, where applicable, superseded for the purposes of this prospectus to the extent that a statement contained in this prospectus or any subsequently filed document that also is incorporated by reference into this prospectus modifies or supersedes such prior statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus.

We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, upon written or oral request and without charge, a copy of the documents referred to above that we have incorporated by reference into this prospectus and a copy of the registration statement of which this prospectus is a part. You can request copies of such documents if you write us at our principal executive offices at 2290 North 1st Street, Suite 201 San Jose, CA 95131, or call our telephone number at (408) 434-6040.

Exhibits to the documents will not be sent, however, unless those exhibits have specifically been incorporated by reference into such document. You may also obtain copies of our SEC filings statement as described above under the heading “Where You Can Find More Information.”

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, any accompanying prospectus supplement and the documents incorporated by reference herein and therein may contain forward-looking statements as defined by the Private Securities Litigation Reform Act of 1995. Our forward-looking statements include, but are not limited to, statements regarding our and our management team’s expectations, hopes, beliefs, intentions or strategies regarding the future. In addition, any statements that refer to projections, forecasts or other characterizations of future events or circumstances, including any underlying assumptions, are forward-looking statements. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intends,” “may,” “might,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “will,” “would” and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking.

Forward-looking statements are not guarantees of performance. You should not put undue reliance on these statements which speak only as of the date hereof. You should understand that the following important factors, among others, could affect the Company’s future results and could cause those results or other outcomes to differ materially from those expressed or implied in the Company’s forward-looking statements:

These and other factors that could cause actual results to differ from those implied by the forward-looking statements in this prospectus are more fully described in the “Risk Factors” section. The risks described in “Risk Factors” are not exhaustive. 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. New risk factors emerge from time to time and it is not possible for us to predict all such risk factors, nor can we assess the impact of all such risk factors on our business or the extent to which any factor or combination of factors may cause actual results to differ materially from those contained in any forward-looking statements. All forward-looking statements attributable to us or persons acting on our behalf are expressly qualified in their entirety by the foregoing cautionary statements. We undertake no obligations to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

USE OF PROCEEDS

Unless we inform you otherwise in the prospectus supplement or a free writing prospectus, we intend to use the net proceeds from the sale of the securities for general corporate purposes, including, but not limited to, working capital, capital expenditures, repayment of indebtedness, investments in our subsidiaries, business acquisitions and the repurchase, redemption or retirement of our securities, including shares of our common stock. We may also invest the net proceeds in U.S. government securities, certificates of deposit or other interest-bearing securities. If we decide to use the net proceeds from a particular offering of securities for a specific purpose, we will describe that in the prospectus supplement relating to that offering.

DESCRIPTION OF COMMON STOCK

The following summary of the material terms of our securities is not intended to be a complete summary of the rights and preferences of such securities. The descriptions below are qualified by reference to the actual text of our Second Amended and Restated Certificate of Incorporation (our “Charter”). We urge you to read our Charter in its entirety for a complete description of the rights and preferences of our securities.

Authorized and Outstanding Capital Stock

Our Charter authorizes the issuance of 400,000,000 shares of Common Stock, $0.0001 par value per share and 40,000,000 shares of Preferred Stock, $0.0001 par value.

As of March 20, 2025, there were 48,246,480 shares of Common Stock issued and outstanding and no shares of Preferred Stock issued and outstanding.

Voting Power

Except as otherwise provided by the General Corporate Law of the State of Delaware (the "DGCL") or our Charter and subject to the rights of holders of any series of Preferred Stock, all of the voting power of our stockholders will be vested in the holders of our Common Stock, and each holder of our Common Stock will have one vote for each share held by such holder on all matters voted upon by the stockholders of the Company; provided, however, that, except as otherwise required by law, holders of our Common Stock, as such, will not be entitled to vote on any amendment to our Charter (or on any amendment to a certificate of designations of any series of Preferred Stock) that alters or changes the powers, preferences, rights or other terms of one or more outstanding series of Preferred Stock if the holders of such affected series of Preferred Stock are entitled to vote, either separately or together with the holders of one or more other such series, on such amendment pursuant to our Charter (or pursuant to a certificate of designations of any series of Preferred Stock) or pursuant to the DGCL. There will be no cumulative voting.

Dividends

Except as otherwise provided by the DGCL or our Charter, dividends may be declared and paid on our Common Stock from funds lawfully available therefor if, as and when determined by our Board and subject to any preferential dividend rights of any then outstanding shares of Preferred Stock.

Liquidation

Upon the dissolution or liquidation or winding up of the affairs of the Company, whether voluntary or involuntary, holders of our Common Stock will be entitled to receive all our assets available for distribution to our stockholders equally on a per share basis, subject to any preferential rights of any then outstanding shares of Preferred Stock and after payment or provision for payment of our debts.

Preemptive Rights; Redemption Rights

The holders of our Common Stock will have no preemptive rights to subscribe for any shares of any class of our stock. Our Common Stock will not be convertible into, or exchangeable for, shares of any other class or classes or of any other series of the same class of our capital stock.

Listing

Our Common Stock and our Warrants are currently listed on the NYSE under the symbols “GCTS” and “GCTS-WT,” respectively.

Transfer Agent and Registrar

The transfer agent and registrar for our Common Stock is Continental Stock Transfer & Trust Company.

DESCRIPTION OF PREFERRED STOCK

Our Charter provides that shares of our Preferred Stock may be issued from time to time in one or more series. Our Board will be authorized to establish the voting rights, if any, designations, preferences and relative, participating, optional or other special rights of the shares of such series, and the qualifications, limitations or restrictions thereof, applicable to the shares of each series of our Preferred Stock. Our Board can, without stockholder approval, issue our Preferred Stock with voting and other rights that could adversely affect the voting power and other rights of the holders of our Common Stock and could have anti-takeover effects. The ability of our Board to issue our Preferred Stock without stockholder approval could have the effect of delaying, deferring or preventing a change of control or the removal of existing management. We have no Preferred Stock outstanding at the date hereof.

DESCRIPTION OF WARRANTS

The following summarizes the general terms of stock and debt warrants that we may offer. The particular terms of any stock and debt warrants will be described in an accompanying prospectus supplement. The description below and in any accompanying prospectus supplement is not complete. You should read the form of warrant agreement and any warrant certificate that we will file with the SEC.

Warrants to Purchase Capital Stock

If we offer stock warrants, the prospectus supplement will describe the terms of the stock warrants, including:

The shares of Common Stock or Preferred Stock we issue upon exercise of the stock warrants will, when issued in accordance with the stock warrant agreement, be validly issued, fully paid and nonassessable.

Exercise of Warrants to Purchase Capital Stock

You may exercise stock warrants by surrendering to the stock warrant agent the stock warrant certificate, which indicates your election to exercise all or a portion of the stock warrants evidenced by the certificate. Surrendered stock warrant certificates must be accompanied by payment of the exercise price in the form of cash or check. The stock warrant agent will deliver certificates evidencing duly exercised stock warrants to the transfer agent. Upon receipt of the certificates, the transfer agent will deliver a certificate representing the number of shares of Common Stock or Preferred Stock purchased. If you exercise fewer than all the stock warrants evidenced by any certificate, the stock warrant agent will deliver a new stock warrant certificate representing the unexercised stock warrants.

No Rights as Stockholders

Holders of stock warrants are not entitled to vote, to consent, to receive dividends or to receive notice as stockholders with respect to any meeting of stockholders or to exercise any rights whatsoever as our stockholders.

Warrants to Purchase Debt Securities

If we offer debt warrants, the accompanying prospectus supplement will describe the terms of the warrants, including:

You may exchange debt warrant certificates for new debt warrant certificates of different denominations and may present debt warrant certificates for registration of transfer at the corporate trust office of the debt warrant agent, which will be listed in an accompanying prospectus supplement.

Exercise of Warrants to Purchase Debt Securities

You may exercise debt warrants by surrendering the debt warrant certificate at the corporate trust office of the debt warrant agent, with payment in full of the exercise price. Upon the exercise of debt warrants, the debt warrant agent will, as soon as practicable, deliver the debt securities in authorized denominations in accordance with your instructions and at your sole cost and risk. If less than all the debt warrants evidenced by the debt warrant certificate are exercised, the agent will issue a new debt warrant certificate for the remaining amount of debt warrants.

No Rights as Holders of Debt Securities

Warrant holders do not have any of the rights of holders of debt securities, except to the extent that the consent of warrant holders may be required for certain modifications of the terms of an indenture or form of the debt security, as the case may be, and the series of debt securities issuable upon exercise of the debt warrants. In addition, warrant holders are not entitled to payments of principal of and interest, if any, on the debt securities.

DESCRIPTION OF DEBT SECURITIES

General

We may issue debt securities either separately, or together with, or upon the conversion or exercise of or in exchange for, other securities described in this prospectus. Debt securities may be our senior, senior subordinated or subordinated obligations and may be issued in one or more series. Unless otherwise expressly stated in an accompanying prospectus supplement, the debt securities will represent our general, unsecured obligations and will rank equally with all of our other unsecured indebtedness.

Any debt securities that we issue will be issued under an indenture that will be entered into between us and a bank or trust company, or other trustee that is qualified to act under the Trust Indenture Act of 1939 (the “TIA”), which we select to act as trustee. A copy of the indenture (the “Indenture”) will be filed as an exhibit to a prospectus supplement to the registration statement of which this prospectus forms a part. The Indenture may be modified by one or more supplemental indentures, which we will incorporate by reference as an exhibit to the registration statement of which this prospectus is a part. Any debt securities that we issue will include those stated in the Indenture (including any supplemental indentures that specify the terms of a particular series of debt securities) as well as those made part of the Indenture by reference to the TIA, as in effect on the date of the Indenture. The Indenture will be subject to and governed by the terms of the TIA.

The following description and any description in an accompanying prospectus supplement is a summary only and is subject to, and qualified in its entirety by reference to the terms and provisions of the indentures and any supplemental indentures that we file with the SEC in connection with an issuance of any series of debt securities. You should read all of the provisions of the Indentures, including the definitions of certain terms, as well as any supplemental indentures that we file with the SEC in connection with the issuance of any series of debt securities. These summaries set forth certain general terms and provisions of the securities to which any accompanying prospectus supplement may relate. The specific terms and provisions of a series of debt securities and the extent to which the general terms and provisions may also apply to a particular series of debt securities will be described in the accompanying prospectus supplement. Copies of the Indenture may be obtained from us or the Trustee.

Please read the accompanying prospectus supplement relating to the series of debt securities being offered for specific terms including, when applicable:

As used in this prospectus and any accompanying prospectus supplement relating to the offering of debt securities of any series, references to the principal of and premium, if any, and interest, if any, on the debt securities of the series include the payment of Additional Amounts, if any, required by the debt securities of the series to be paid in that context.

Debt securities may be issued as original issue discount securities to be sold at a substantial discount below their principal amount. In the event of an acceleration of the maturity of any original issue discount security, the amount payable to the holder upon acceleration will be determined in the manner described in the accompanying prospectus supplement. Certain U.S. federal income tax considerations applicable to original issue discount securities will be described in any accompanying prospectus supplement.

If the purchase price of any debt securities is payable in a foreign currency or if the principal of, or premium, if any, or interest, if any, on any debt securities is payable in a foreign currency, the specific terms of those debt securities and the applicable foreign currency will be specified in the accompanying prospectus supplement relating to those debt securities.

The terms of the debt securities of any series may differ from the terms of the debt securities of any other series, and the terms of particular debt securities within any series may differ from each other. Unless otherwise expressly provided in the accompanying prospectus supplement relating to any series of debt securities, we may, without the consent of the holders of the debt securities of any series, reopen an existing series of debt securities and issue additional debt securities of that series.

Unless otherwise described in an accompanying prospectus supplement relating to any series of debt securities, there will be no limitation upon our ability to incur indebtedness or other liabilities or that would afford holders of debt securities protection in the event of a business combination, takeover, recapitalization or highly leveraged or similar transaction involving us. Accordingly, we may in the future enter into transactions that could increase the amount of our consolidated indebtedness and other liabilities or otherwise adversely affect our capital structure or credit rating without the consent of the holders of the debt securities of any series.

Registration, Transfer and Payment

Unless otherwise indicated in the applicable prospectus supplement, each series of debt securities will be issued in registered form only, without coupons.

Unless otherwise indicated in the applicable prospectus supplement, debt securities will be issued in denominations of $1,000 or any integral multiples of $1,000 in excess thereof.

Unless otherwise indicated in the accompanying prospectus supplement, the debt securities will be payable and may be surrendered for registration of transfer or exchange and, if applicable, for conversion into or exchange for other securities or property, at an office or agency maintained by us in the United States. However, we may, at our option, make payments of interest on any registered debt security by check mailed to the address of the person entitled to receive that payment or by wire transfer to an account maintained by the payee with a bank located in the United States. Unless otherwise indicated in the accompanying prospectus supplement, no service charge shall be made for any registration of transfer or exchange, redemption or repayment of debt securities, or for any conversion or exchange of debt securities for other securities or property, but we may require payment of a sum sufficient to cover any tax or other governmental charge that may be imposed in connection with that transaction.

Unless otherwise indicated in the applicable prospectus supplement, we will not be required to:

Book-Entry Debt Securities

We may issue the debt securities in whole or in part in the form of one or more global certificates or notes, which we refer to as global securities, that we will deposit with a depository or its nominee that we identify in the applicable prospectus supplement.

We will describe the specific terms of the depository arrangement covering the debt securities in the prospectus supplement relating to that series. We anticipate that the following provisions will apply to all depository arrangements.

Upon the issuance of the debt securities in the form of one or more global securities, the depository or its custodian will credit, on its book-entry registration and transfer system, the number of shares or principal amount of securities of the individual beneficial interests represented by these global securities to the respective accounts of persons who have accounts with the depository. Ownership of beneficial interests in the global securities will be shown on, and the transfer of this ownership will be effected only through, records maintained by the depository or its nominee with respect to interests of participants and the records of participants with respect to interests of persons other than participants. These accounts initially will be designated by or on behalf of the underwriters, initial purchasers or agents, or by us if we offer and sell the debt securities directly, and ownership of beneficial interests in the global securities will be limited to participants or persons who hold interests through participants. Qualified institutional buyers may hold their interests in the global securities directly through the depository if they are participants in this system, or indirectly through organizations which are participants in this system. The laws of some states of the U.S. may require that some purchasers of securities take physical delivery of the debt securities in definitive registered form. These limits and the laws may impair your ability to own, transfer or pledge interests in the global securities.

So long as the depository, or its nominee, is the registered owner or holder of the debt securities, the depository or its nominee, as the case may be, will be considered the sole owner or holder of the debt securities represented by the global securities for all purposes. No beneficial owner of an interest in the global securities will be able to transfer that interest except in accordance with the depository’s procedures.

We will make dividend payments on, or payments of the principal of, and premium, if any, and interest on, the global securities to the depository or its nominee, as the case may be, as the registered owner of the global securities. We will not have any responsibility or liability for any aspect of the records relating to or payments made on account of beneficial ownership interests in the global securities or for maintaining, supervising or reviewing any records relating to the beneficial ownership interest.

We expect that the depository or its nominee, upon receipt of any dividend payment on, or payment of the principal of, and premium, if any, and interest on, the global securities, will credit participants’ accounts with payments in amounts proportionate to their respective beneficial interests in the debt securities as shown on the records of the depository or its nominee. We also expect that payments by participants to owners of beneficial interests in the global securities held through the participants will be governed by standing instructions and customary practice, as is now the case with securities held for the accounts of customers registered in the names of nominees for their customers. These payments will be the responsibility of the participants. Transfers between participants in the depository will be effected in the ordinary way through the depository’s settlement system in accordance with the depository rules and will be settled in same day funds.

We will issue securities in certificated form in exchange for global securities (subject, in the case of the third bullet point, to the procedures of the depository) if:

DESCRIPTION OF RIGHTS

As specified in the applicable prospectus supplement, we may issue rights to purchase the securities offered in this prospectus to our existing stockholders, and such rights may or may not be issued for consideration. The applicable prospectus supplement will describe the terms of any such rights. The description in the prospectus supplement will not purport to be complete and will be qualified in its entirety by reference to the documents pursuant to which such rights will be issued.

DESCRIPTION OF UNITS

As may be specified in an accompanying prospectus supplement, we may issue units consisting of one or more of our securities registered hereby. An accompanying prospectus supplement will describe:

PLAN OF DISTRIBUTION

We may offer and sell the securities under this prospectus from time to time in one or more of the following ways:

The distribution of the securities may be made from time to time in one or more transactions, either:

Through Agents

We and the agents designated by us may solicit offers to purchase securities. Agents that participate in the distribution of securities may be deemed underwriters under the Securities Act of 1933, as amended (which we refer to as the “Securities Act”). Any agent will be acting on a “best efforts” basis for the period of its appointment, unless we indicate differently in the prospectus supplement.

To Dealers

The securities may be sold to a dealer as principal. The dealer may then resell the securities to the public at varying prices determined by it at the time of resale. The dealer may be deemed to be an underwriter under the Securities Act.

To Underwriters

We may sell securities to one or more underwriters under an underwriting agreement that we enter into with them at the time of sale. The names of the underwriters will be set forth in the prospectus supplement, which will be used by the underwriters to resell the securities.

In addition, we may enter into derivative transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement indicates, in connection with such a transaction, that the third parties may sell securities covered by this prospectus and the applicable prospectus supplement, including in short sale transactions. If so, the third party may use securities pledged by us or borrowed from us or others to settle such sales or to close out any related open borrowings of stock, and may use securities received from us in settlement of a derivative transaction to close out any related open borrowings of stock. We otherwise may loan or pledge securities to a financial institution or other third party that in turn may sell the loaned securities or, in an event of default in the case of a pledge, sell the pledged securities, in either case using this prospectus and the applicable prospectus supplement.

Direct Sales

We may sell securities directly to you, without the involvement of underwriters or agents.

General Information

Any underwriters or agents will be identified and their compensation described in the prospectus supplement applicable to such offering.

We may have agreements with the underwriters, dealers and agents to indemnify them against certain civil liabilities, including liabilities under the Securities Act, or to contribute to payments they may be required to make.

Underwriters, dealers and agents (or one or more of their respective affiliates) may engage in transactions with, or perform services for, us or our subsidiaries in the ordinary course of their businesses.

LEGAL MATTERS

Unless otherwise indicated in the applicable prospectus supplement, the validity of the securities offered by this prospectus will be passed upon for us by Morgan, Lewis & Bockius LLP, Palo Alto, California, and for any underwriters or agents by counsel named in the applicable prospectus supplement.

EXPERTS

The consolidated financial statements of the Company as of December 31, 2024 and 2023, and for each of the two years in the period ended December 31, 2024, incorporated in this registration statement by reference to the Annual Report on Form 10-K for the year ended December 31, 2024, have been so incorporated in reliance on the report (which contains an explanatory paragraph relating to the Company’s ability to continue as a going concern as described in Note 1 to the consolidated financial statements) of BPM LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

$200,000,000

GCT Semiconductor Holding, Inc.

Common Stock

Preferred Stock

Debt Securities

Warrants

Rights

Units

Prospectus

_______, 2025

You should rely only on the information contained or incorporated by reference in this prospectus. We have not authorized anyone to provide you with different information. You should not assume that the information contained or incorporated by reference in this prospectus is accurate as of any date other than the date of this prospectus. We are not making an offer of these securities in any state where the offer is not permitted.

TABLE OF CONTENTS

The distribution of this prospectus and sale of these securities in certain jurisdictions may be restricted. Persons in possession of this prospectus are required to inform themselves about and observe any such restrictions. We are not making an offer of these securities in any jurisdiction where the offer is not permitted.

All references in this prospectus to “we,” “us,” “our,” and “GCT” refer only to GCT Semiconductor Holding, Inc. and not to any existing or future subsidiaries of GCT Semiconductor Holding, Inc., unless the context otherwise requires.

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement on Form S-3 that we filed with the Securities and Exchange Commission (the “SEC”) using a “shelf” registration process. Under this prospectus, we may offer shares of our Common Stock having an aggregate offering price set forth on the cover page hereof, 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 shares of Common Stock offered hereby, we urge you to read carefully this prospectus, the accompanying base prospectus and all of the information incorporated herein by reference in this prospectus and the accompanying base prospectus, as well as the additional information described below under the heading “Documents Incorporated by Reference.” These documents contain important information that you should consider when making your investment decision.

We provide information to you about this offering of our Common Stock in two separate documents that are bound together: (1) this prospectus, which describes the specific details regarding this offering; and (2) the accompanying base prospectus, which provides general information, some of which may not apply to this offering. Generally, when we refer to this “prospectus,” we are referring to both documents combined. If information in this prospectus is inconsistent with the accompanying base prospectus, you should rely on this prospectus. To the extent there is a conflict between the information contained in this prospectus, on the one hand, and the information contained in any document incorporated by reference in this prospectus that was filed with the SEC before the date of 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 document incorporated by reference in this prospectus—the statement in the document having the later date modifies or supersedes the earlier statement.

We have not, and the sales agents have not, authorized anyone to provide you with information other than the information that we have provided or incorporated by reference in this prospectus, the accompanying base prospectus or any other prospectus supplement and your reliance on any unauthorized information or representation is at your own risk. This prospectus may be used only in jurisdictions where offers and sales of these securities are permitted. You should assume that the information appearing in this prospectus is accurate only as of the date of this prospectus and that any information we have incorporated by reference is accurate only as of the date of the document incorporated by reference, regardless of the time of delivery of this prospectus, or any sale of our Common Stock. Our business, financial condition and results of operations may have changed since those dates.

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 take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. This prospectus and the accompanying prospectus is an offer to sell only the securities offered hereby and only under circumstances and in jurisdictions where it is lawful to do so. No dealer, salesperson or other person is authorized to give any information or to represent anything not contained in this prospectus, accompanying prospectus, and any free writing prospectuses prepared by or on behalf of us or to which we have referred you or are incorporated by reference. This prospectus is not an offer to sell securities, and it is not soliciting an offer to buy securities, in any jurisdiction where the offer or sale is not permitted.

Unless otherwise stated, all references in this prospectus to “we,” “us,” “our,” “GCT,” the “Company” and similar designations refer to GCT Semiconductor Holding Inc.

RISK FACTORS

Investing in our Common Stock involves substantial risk. You should carefully consider the risk factors disclosed below as well as those contained in our most recent Annual Report on Form 10-K, which is incorporated by reference herein, as updated by our subsequent filings under the Exchange Act, and the other information contained in this prospectus before acquiring any of our common stock. These risks could have a material adverse effect on our business, results of operations or financial condition and cause the value of our common stock to decline. You could lose all or part of your investment.

This prospectus also contains or incorporates by reference forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those anticipated in the forward-looking statements as a result of certain factors, including the risks faced by us described or incorporated by reference in this prospectus. See “Cautionary Note Regarding Forward-Looking Statements.”

Risks Related to our Common Stock and the Offering

Our management will have broad discretion as to the use of proceeds from this offering and we may not use the proceeds effectively.

Our management will have broad discretion in the application of the net proceeds from this offering, if any, and could spend the proceeds in ways that do not improve our results of operations or enhance the value of our Common Stock. You will be relying on the judgment of our management concerning these uses and you will not have the opportunity, as part of your investment decision, to assess whether the proceeds are being used appropriately. The failure of our management to apply these funds effectively could result in unfavorable returns and uncertainty about our prospects, each of which could cause the price of our Common Stock to decline.

There may be future dilution of our Common Stock as a result of future sales of our Common Stock, which could adversely impact our stock price.

The issuance of shares of our Common Stock from time to time pursuant to the sales agreement may have a dilutive effect on our earnings per share, which could adversely impact the market price of our Common Stock. The actual amount of dilution and the effect on the market price of our Common Stock, if any, will be based on numerous factors, particularly the actual number of shares issued pursuant to the sales agreement, the use of proceeds and the return generated by the investments acquired with the net proceeds, and cannot be determined at this time. In addition, the issuance and sale of substantial amounts of our Common Stock, or the perception that such issuances and sales may occur, could adversely affect the market price of our Common Stock and impair our ability to raise capital through the sale of additional equity securities. Additionally, the sale of shares of Common Stock in this offering will increase the supply of available shares, which may result in a decrease in the price of our Common Stock.

The shares of our Common Stock offered under this prospectus will be sold in “at the market offerings”, and investors who buy shares at different times will likely pay different prices.

Investors who purchase shares under this prospectus 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 shares sold, and to determine the minimum sales price for shares sold. Investors may experience declines in the value of their shares as a result of share sales made in connection with “at the market offerings” at prices lower than the prices they paid.

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

Subject to certain limitations in the sales agreement and compliance with applicable law, we and our sales agents may mutually agree to sell shares of our Common Stock under a placement notice at any time throughout the term of the sales agreement. The number of shares that are sold by our sales agents in connection with any placement notice will fluctuate based on the market price of the shares of our Common Stock during the sales period and limits we set with our sales agents. Because the price per share of each share sold will fluctuate based on the market price of our shares of Common Stock during the sales period, it is not possible to predict the number of shares that will ultimately be issued.

Our stock price may fluctuate significantly, and investors may not be able to sell their shares at an attractive price.

The trading price of our Common Stock may be volatile and subject to wide price fluctuations in response to various factors including:

These and other factors may cause the market price and demand for our Common Stock to fluctuate substantially, which may limit or prevent investors from readily selling their shares of our Common Stock and may otherwise negatively affect the liquidity of our Common Stock. In addition, in the past, when the market price of a stock has been volatile, holders of that stock have sometimes instituted securities class action litigation against the company that issued the stock. If any of our stockholders were to bring a lawsuit against us, we could incur substantial costs defending the lawsuit. Such a lawsuit could also divert the time and attention of our management from our business.

An investor’s percentage of ownership in the Company may be diluted in the future.

As with any publicly traded company, an investor’s percentage ownership in the Company may be diluted in the future because of the issuance of additional Common Stock. From time to time, we have issued and we expect we will continue to issue stock options or restricted stock grants or similar awards to employees, officers, and directors pursuant to our equity incentive award plans. Investors in our equity securities may experience dilution as these awards vest and are exercised by their holders and as the restrictions lapse on the restricted stock grants. We also may issue Common Stock, preferred stock or warrants of the Company to purchase Common Stock or preferred stock to raise capital to fund our growth initiatives in connection with acquisitions or the settlement of obligations or indebtedness, which would result in further dilution of existing stockholders. The issuance of any such shares of Common Stock, preferred stock or warrants to purchase Common Stock or preferred stock may result in a reduction of the book value or market price of the outstanding shares of our Common Stock.

We do not expect to pay dividends to holders of our Common Stock.

We currently intend to retain our future earnings, if any, for the foreseeable future, to repay indebtedness and to fund the development and growth of our business. We do not intend to pay any dividends to holders of our Common Stock. As a result, capital appreciation in the price of our Common Stock, if any, will be investors’ only source of gain or income on an investment in our Common Stock.

WHERE YOU CAN FIND MORE INFORMATION

We are subject to certain information reporting requirements of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and, in accordance with these requirements, we file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to you at the SEC’s website at http://www.sec.gov and our website at https://investors.gctsemi.com/sec-filings. The information contained in, or that can be accessed through, our website is not a part of this prospectus or any accompanying prospectus supplement.

We have filed with the SEC a registration statement on Form S-3 relating to the securities offered by this prospectus. This prospectus is a part of that registration statement, which includes additional information about us and the securities offered by this prospectus. You may review and obtain a copy of the registration statement and the exhibits that are a part of the registration statement through the SEC’s website or our website. You can also call or write us for a copy as described below under “Documents Incorporated by Reference.”

DOCUMENTS INCORPORATED BY REFERENCE

The SEC allows us to “incorporate by reference” the information we file with the SEC under the Exchange Act, which means that we can disclose important information to you by referring you to those documents. Information incorporated by reference is considered to be a part of this prospectus, and information that we file later with the SEC will automatically update, modify and, where applicable, supersede this information. We incorporate by reference into this prospectus the specific documents listed below and all documents filed by us with the SEC pursuant to Section 13(a), 13(c), 14, or 15(d) of the Exchange Act between the date of this prospectus and the termination of the offering of securities under this prospectus (other than, in each case, documents or information deemed to be furnished and not filed in accordance with SEC rules), which future filings shall be deemed to be incorporated by reference into this prospectus and to be part of this prospectus from the date we subsequently file such documents. The SEC file number for these documents is 1-41013.

Any statement contained in this prospectus or in any document incorporated by reference into this prospectus shall be deemed to be modified or, where applicable, superseded for the purposes of this prospectus to the extent that a statement contained in this prospectus or any subsequently filed document that also is incorporated by reference into this prospectus modifies or supersedes such prior statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus.

We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, upon written or oral request and without charge, a copy of the documents referred to above that we have incorporated by reference into this prospectus and a copy of the registration statement of which this prospectus is a part. You can request copies of such documents if you write us at our principal executive offices at 2290 North 1st Street, Suite 201 San Jose, CA 95131, or call our telephone number at (408) 434-6040.

Exhibits to the documents will not be sent, however, unless those exhibits have specifically been incorporated by reference into such document. You may also obtain copies of our SEC filings statement as described above under the heading “Where You Can Find More Information.”

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, any accompanying prospectus supplement and the documents incorporated by reference herein and therein may contain forward-looking statements as defined by the Private Securities Litigation Reform Act of 1995. Our forward-looking statements include, but are not limited to, statements regarding our and our management team’s expectations, hopes, beliefs, intentions or strategies regarding the future. In addition, any statements that refer to projections, forecasts or other characterizations of future events or circumstances, including any underlying assumptions, are forward-looking statements. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intends,” “may,” “might,” “plan,” “possible,” “potential,” “predict,” “project,” “should,” “will,” “would” and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking.

Forward-looking statements are not guarantees of performance. You should not put undue reliance on these statements which speak only as of the date hereof. You should understand that the following important factors, among others, could affect the Company’s future results and could cause those results or other outcomes to differ materially from those expressed or implied in the Company’s forward-looking statements:

These and other factors that could cause actual results to differ from those implied by the forward-looking statements in this prospectus are more fully described in the “Risk Factors” section. The risks described in “Risk Factors” are not exhaustive. 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. New risk factors emerge from time to time and it is not possible for us to predict all such risk factors, nor can we assess the impact of all such risk factors on our business or the extent to which any factor or combination of factors may cause actual results to differ materially from those contained in any forward-looking statements. All forward-looking statements attributable to us or persons acting on our behalf are expressly qualified in their entirety by the foregoing cautionary statements. We undertake no obligations to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

USE OF PROCEEDS

We may issue and sell shares of our Common Stock having aggregate gross sale proceeds of up to $75,000,000 from time to time.

There can be no assurance that we will be able to sell any shares under or fully utilize the sales agreement with the sales agents as a source of financing. 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.

We currently intend to use the net proceeds, if any, from this offering, after deducting the sales agent’s commissions and our offering expenses, for general corporate purposes, which may include working capital needs, capital expenditures, repayment or refinancing of indebtedness, acquisitions of complementary businesses or assets, stock repurchases and redemptions of securities. The amounts and timing of our use of proceeds will vary depending on many factors, including regulatory developments, the amount of cash generated or used by our operations, and the rate of growth, if any, of our business and other capital requirements. As a result, we will retain broad discretion in the allocation of the net proceeds, if any, we receive in connection with securities offered pursuant to this prospectus, and investors will be relying on the judgment of our management regarding the application of the proceeds.

DESCRIPTION OF COMMON STOCK

The following summary of the material terms of our securities is not intended to be a complete summary of the rights and preferences of such securities. The descriptions below are qualified by reference to the actual text of our Second Amended and Restated Certificate of Incorporation (our “Charter”). We urge you to read our Charter in its entirety for a complete description of the rights and preferences of our securities.

Authorized and Outstanding Capital Stock

Our Charter authorizes the issuance of 400,000,000 shares of Common Stock, $0.0001 par value per share and 40,000,000 shares of Preferred Stock, $0.0001 par value.

As of March 20, 2025, there were 48,246,480 shares of Common Stock issued and outstanding and no shares of Preferred Stock issued and outstanding.

Voting Power

Except as otherwise provided by the DGCL or our Charter and subject to the rights of holders of any series of Preferred Stock, all of the voting power of our stockholders will be vested in the holders of our Common Stock, and each holder of our Common Stock will have one vote for each share held by such holder on all matters voted upon by the stockholders of the Company; provided, however, that, except as otherwise required by law, holders of our Common Stock, as such, will not be entitled to vote on any amendment to our Charter (or on any amendment to a certificate of designations of any series of Preferred Stock) that alters or changes the powers, preferences, rights or other terms of one or more outstanding series of Preferred Stock if the holders of such affected series of Preferred Stock are entitled to vote, either separately or together with the holders of one or more other such series, on such amendment pursuant to our Charter (or pursuant to a certificate of designations of any series of Preferred Stock) or pursuant to the DGCL. There will be no cumulative voting.

Dividends

Except as otherwise provided by the DGCL or our Charter, dividends may be declared and paid on our Common Stock from funds lawfully available therefor if, as and when determined by our Board and subject to any preferential dividend rights of any then outstanding shares of Preferred Stock.

Liquidation

Upon the dissolution or liquidation or winding up of the affairs of the Company, whether voluntary or involuntary, holders of our Common Stock will be entitled to receive all our assets available for distribution to our stockholders equally on a per share basis, subject to any preferential rights of any then outstanding shares of Preferred Stock and after payment or provision for payment of our debts.

Preemptive Rights; Redemption Rights

The holders of our Common Stock will have no preemptive rights to subscribe for any shares of any class of our stock. Our Common Stock will not be convertible into, or exchangeable for, shares of any other class or classes or of any other series of the same class of our capital stock.

Listing

Our Common Stock and our Warrants are currently listed on the NYSE under the symbols “GCTS” and “GCTS-WT,” respectively.

Transfer Agent and Registrar

The transfer agent and registrar for our Common Stock is Continental Stock Transfer & Trust Company.

PLAN OF DISTRIBUTION

We have entered into an At Market Issuance Sales Agreement (the “sales agreement”) with B. Riley Securities, Inc. and H.C. Wainwright & Co., LLC (the “sales agents”), as our sales agents, under which we may issue and sell shares of our Common Stock having an aggregate offering price of up to $75,000,000 from time to time through or to the sales agents as sales agents or principal. The sales agents may sell the Common Stock by any method that is deemed to be an “at the market offering” as defined in Rule 415 promulgated under the Securities Act.

Each time we wish to issue and sell Common Stock under the sales agreement, we will notify the sales agents of the number or dollar value of shares to be issued, the dates on which such sales are anticipated to be made, any limitation on the number of shares that may be sold in one day, any minimum price below which sales may not be made, and other sales parameters as we deem appropriate. Once we have so instructed a sales agent, unless such sales agent declines to accept the terms of such notice, such sales agent has agreed to use its commercially reasonable efforts consistent with its normal trading and sales practices to sell such shares up to the amount specified on such terms. The obligations of the sales agents under the sales agreement to sell our Common Stock are subject to a number of customary conditions that we must meet. We may instruct the sales agents not to sell our Common Stock if the sales cannot be effected at or above the price designated by us in any such instruction. We and the sales agents may suspend the offering of Common Stock upon proper notice to the other party and subject to other conditions. We and the sales agents each have the right, by giving written notice as specified in the sales agreement, to terminate the sales agreement in each party’s sole discretion at any time upon five days’ prior notice.

Under the terms of the sales agreement, we may also sell our Common Stock to the sales agents, as principal for their own account, at a price negotiated at the time of sale, provided that no sales may be made in a principal transaction without our prior consent.

Unless otherwise specified in the applicable placement notice, settlement for shares of our Common Stock will occur on the trading day following the date on which the sales are made. Sales of our Common Stock as contemplated in this prospectus will be settled through the facilities of The Depository Trust Company or by such other means as we and the sales agents may agree upon. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

We will pay the sales agents a commission for their services in acting as agents in the sale of Common Stock at a commission rate of equal to 3.0% of the gross proceeds from each sale. We also agreed to reimburse the sales agents for certain specified fees and documented expenses, including the fees and documented expenses of their legal counsel in an amount not to exceed $75,000, plus an additional amount not to exceed $5,000 per fiscal quarter on an ongoing basis during the term of the sales agreement, as provided in 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. In addition, we will pay H.C. Wainwright & Co., LLC an additional financial advisory fee equal to 0.27% of the gross proceeds received by us from the sale of Common Stock made through or to the Agents pursuant to the sales agreement. We estimate that the total expenses for the offering, excluding compensation payable to the sales agents and expense reimbursement under the terms of the sales agreement, will be up to approximately $236,120.

In addition, the sales agreement provides that we will not (i) take any action designed to cause or result in, or that constitutes or would reasonably be expected to constitute, the stabilization or manipulation of the price of any of our securities to facilitate the sale or resale of Common Stock, or (ii) sell, bid for, or purchase Common Stock in violation of Regulation M, or pay anyone any compensation for soliciting purchases of the Common Stock under the sales agreement other than the sales agents.

In connection with the sale of the Common Stock on our behalf, each sales agent will be deemed to be an “underwriter” within the meaning of the Securities Act as amended, and its compensation will be deemed to be underwriting commissions or discounts. We have agreed to provide indemnification and contribution to the sales agents with respect to certain liabilities, including civil liabilities under the Securities Act.

The offering of our Common Stock pursuant to the sales agreement will terminate upon the earlier of (1) the issuance and sale of all Common Stock subject to the sales agreement; and (2) the termination of the sales agreement as described therein.

In April 2024, the Company entered into a common stock purchase agreement (the “Purchase Agreement”) and a related registration rights agreement (the “Registration Rights Agreement”) with B. Riley Principal Capital II, LLC, an affiliate of B. Riley Securities, Inc. (“B. Riley Principal Capital II”). Upon the terms and subject to the satisfaction of the conditions set forth in the Purchase Agreement, the Company has the right, in its sole discretion, to sell to B. Riley Principal Capital II, from time to time, up to $50.0 million in aggregate gross purchase price of shares of the Company’s common stock, subject to certain limitations contained in the Purchase Agreement, during the term of 24 months. Pursuant to the Registration Rights Agreement, the Company has filed a registration statement on Form S-1 to register the resale of shares of common stock that are sold to B. Riley Principal Capital II under the Purchase Agreement. Sales of common stock by the Company to B. Riley Principal Capital II pursuant to the Purchase Agreement, and the timing of any such sales, are solely at the option of the Company, and the Company is under no obligation to sell any securities to B. Riley Principal Capital II under the Purchase Agreement. As of March 20, 2025, the Company has sold an aggregate of 2,438,037 shares of Common Stock pursuant to the Purchase Agreement.

The sales agents and its respective affiliates have in the past and may in the future provide various investment banking and/or other financial services for us and/or our affiliates, for which services they may in the future receive customary fees. To the extent required by Regulation M under the Exchange Act, the sales agents will not engage in any market making activities involving our Common Stock while the offering is ongoing under this prospectus.

This summary of the material provisions of the sales agreement does not purport to be a complete statement of its terms and conditions. A copy of the sales agreement is filed with the SEC as an exhibit to the registration statement of which this prospectus is a part. See “Where You Can Find More Information.”

LEGAL MATTERS

The validity of the shares of Common Stock offered by this prospectus were passed upon by Morgan, Lewis & Bockius LLP, Palo Alto, California. Certain matters will be passed upon for the sales agents by Duane Morris LLP, New York, New York.

EXPERTS

The consolidated financial statements of the Company as of December 31, 2024 and 2023, and for each of the two years in the period ended December 31, 2024, incorporated in this prospectus and elsewhere in the registration statement by reference to the Annual Report on Form 10-K for the year ended December 31, 2024, have been so incorporated in reliance on the report (which contains an explanatory paragraph relating to the Company’s ability to continue as a going concern as described in Note 1 to the consolidated financial statements) of BPM LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

GCT Semiconductor Holding, Inc.

Up to $75,000,000 of Common Stock

Prospectus

B. Riley Securities H.C. Wainwright & Co.

_______, 2025

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution.

Set forth below are the estimated fees and expenses (other than underwriting discounts and commissions) to be incurred by the registrant in connection with the issuance and distribution of the securities registered hereby:

Item 15. Indemnification of Directors and Officers.

Section 145 of the General Corporation Law of the State of Delaware (the “DGCL”) provides, generally, that a corporation shall have the power to indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of the corporation) by reason of the fact that such person is or was a director, officer, employee or agent of the corporation against all expenses, judgments, fines and amounts paid in settlement actually and reasonably incurred by such person in connection with such action, suit or proceeding if such person acted in good faith and in a manner such person reasonably believed to be in or not opposed to the best interests of the corporation and, with respect to any criminal action or proceeding, had no reasonable cause to believe his or her conduct was unlawful. A corporation may similarly indemnify such person for expenses actually and reasonably incurred by such person in connection with the defense or settlement of any action or suit by or in the right of the corporation, provided that such person acted in good faith and in a manner he or she reasonably believed to be in or not opposed to the best interests of the corporation, and, in the case of claims, issues and matters as to which such person shall have been adjudged liable to the corporation, provided that a court shall have determined, upon application, that, despite the adjudication of liability but in view of all of the circumstances of the case, such person is fairly and reasonably entitled to indemnity for such expenses which such court shall deem proper.

In accordance with Section 102(b)(7) of the DGCL, the Charter provides that a director will not be personally liable to us or our stockholders for monetary damages for breach of fiduciary duty as a director, except for liability (i) for any breach of the director’s duty of loyalty to us or our stockholders, (ii) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (iii) under Section 174 of the DGCL, or (iv) for any transaction from which the director derived an improper personal benefit. No such provision shall eliminate or limit the liability of a director for any act or omission occurring prior to the date when such provision became effective. Accordingly, these provisions will have no effect on the availability of equitable remedies such as an injunction or rescission based on a director’s breach of his or her duty of care.

The Charter provides that we will indemnify our present and former directors and officers to the maximum extent permitted by the DGCL and that such indemnification will not be exclusive of any other rights to which those seeking indemnification may be entitled under any bylaw provision, agreement, vote of stockholders or disinterested directors or otherwise.

The Company entered, and expects to continue to enter into, indemnification agreements with its directors, executive officers, and other employees as determined by the Board. Each indemnification agreement provides for indemnification and advancements by the Company of certain expenses and costs, if the basis of the indemnitee’s involvement was by reason of the fact that the indemnitee is or was a director, officer, employee, or agent of the Company or any of its subsidiaries or was serving at the Company’s request in an official capacity for another entity, to the fullest extent permitted by the laws of the state of Delaware.

Item 16. Exhibits

Exhibit Index

* To be filed, if necessary, by amendment or as an exhibit to a report pursuant to section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended, and incorporated herein by reference.

** Filed herewith.

Item 17. Undertakings.

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 S-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in San Jose, California on April 1, 2025.

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints John Schlaefer and Edmond Cheng, and each one of them, as his or her true and lawful attorneys-in-fact and agents, with full power to act alone, with full powers 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 (including post-effective amendments) to this registration statement on Form S-3, and to sign any registration statement for the same offering covered by this registration statement that is to be effective on filing pursuant to Rule 462(b) under the Securities Act of 1933, as amended, and all post-effective amendments thereto, and to file the same, with all exhibits thereto and other documents in connection therewith, with the SEC, granting unto said attorneys-in-fact and agents, and each one 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, as fully for all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or any of them, or her substitute or resubstitute, 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.