Sec Form 4 Filing - Yoon David @ Concord Acquisition Corp III - 2024-03-26

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Yoon David 2. Issuer Name and Ticker or Trading Symbol Concord Acquisition Corp III [ GCTS] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Vice President of Finance (Last) (First) (Middle) C/O GCT SEMICONDUCTOR HOLDING, INC., 2290 NORTH 1ST STREET, SUITE 201 3. Date of Earliest Transaction (MM/DD/YY) 03/26/2024 (Street) SAN JOSE, CA95131 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock, par value $0.0001 per share 03/26/2024 A( 1 ) 30,093 A $ 0 30,093 D Common Stock, par value $0.0001 per share 03/26/2024 A( 2 ) 8,204 A $ 0 8,204 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Stock Option (Right to Buy) $ 0.11 03/26/2024 A( 3 ) 6,536 ( 4 ) 01/01/2025 Common Stock 6,536 $ 0 6,536 D Stock Option (Right to Buy) $ 0.11 03/26/2024 A( 3 ) 9,431 ( 5 ) 01/01/2028 Common Stock 9,431 $ 0 9,431 D Stock Option (Right to Buy) $ 0.11 03/26/2024 A( 3 ) 13,540 ( 6 ) 01/01/2029 Common Stock 13,540 $ 0 13,540 D Stock Option (Right to Buy) $ 0.11 03/26/2024 A( 3 ) 20,543 ( 7 ) 01/01/2030 Common Stock 20,543 $ 0 20,543 D Stock Option (Right to Buy) $ 0.11 03/26/2024 A( 3 ) 18,676 ( 8 ) 01/01/2031 Common Stock 18,676 $ 0 18,676 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Yoon David C/O GCT SEMICONDUCTOR HOLDING, INC. 2290 NORTH 1ST STREET, SUITE 201 SAN JOSE, CA95131 Vice President of Finance Signatures /s/ Edmond Cheng, attorney-in-fact 03/27/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Pursuant to the Business Combination Agreement, dated as of November 2, 2023 (the "Business Combination Agreement"), by and among Concord Acquisition Corp III, Gibraltar Merger Sub Inc., and GCT Semiconductor, Inc. ("GCT"), at the Effective Time (as defined in the Business Combination Agreement), each share of GCT common stock was automatically converted for the right to receive common stock of the Issuer in the manner set forth in the Business Combination Agreement. ( 2 )Represents the Issuer's common stock subject to restricted stock units (RSUs). Pursuant to the Business Combination Agreement, at the Effective Time (as defined in the Business Combination Agreement), each award of restricted stock units relating to a share of GCT common stock granted under GCT's existing equity plans was automatically converted into an award of restricted stock units covering the number of shares of the common stock of the Issuer in the manner set forth in the Business Combination Agreement. The shares subject to RSUs reported herein will vest in equal annual installments over a four (4) year period measured from December 11, 2023. ( 3 )Pursuant to the Business Combination Agreement, at the Effective Time, each outstanding option to purchase shares of GCT common stock was assumed and converted into an option to purchase shares of common stock of the Issuer with the same terms and conditions as were applicable to such option immediately prior to the Effective Time, subject to the applicable exchange ratio. ( 4 )The option vests with respect to (i) twenty-five percent (25%) of the shares upon completion of one (1) year of service measured from January 1, 2015 and (ii) the balance of the shares subject to the option in a series of thirty-six (36) successive equal monthly installments upon completion of each additional month of service over the thirty-six (36) month period measured from January 1, 2016. ( 5 )The option vests with respect to (i) twenty-five percent (25%) of the shares upon completion of one (1) year of service measured from January 1, 2018 and (ii) the balance of the shares subject to the option in a series of thirty-six (36) successive equal monthly installments upon completion of each additional month of service over the thirty-six (36) month period measured from January 1, 2019. ( 6 )The option vests with respect to (i) twenty-five percent (25%) of the shares upon completion of one (1) year of service measured from January 1, 2019 and (ii) the balance of the shares subject to the option in a series of thirty-six (36) successive equal monthly installments upon completion of each additional month of service over the thirty-six (36) month period measured from January 1, 2020. ( 7 )The option vests with respect to (i) twenty-five percent (25%) of the shares upon completion of one (1) year of service measured from January 1, 2020 and (ii) the balance of the shares subject to the option in a series of thirty-six (36) successive equal monthly installments upon completion of each additional month of service over the thirty-six (36) month period measured from January 1, 2021. ( 8 )The option vests with respect to (i) twenty-five percent (25%) of the shares upon completion of one (1) year of service measured from January 1, 2021 and (ii) the balance of the shares subject to the option in a series of thirty-six (36) successive equal monthly installments upon completion of each additional month of service over the thirty-six (36) month period measured from January 1, 2022.

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