Sec Form 4/A Filing - Gregoriou Vassilios @ ADVENT TECHNOLOGIES HOLDINGS, INC. - 2021-06-11

FORM 4/A 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 Gregoriou Vassilios 2. Issuer Name and Ticker or Trading Symbol ADVENT TECHNOLOGIES HOLDINGS, INC. [ ADN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chairman and CEO (Last) (First) (Middle) C/O ADVENT TECHNOLOGIES HOLDINGS, INC., 200 CLARENDON STREET 3. Date of Earliest Transaction (MM/DD/YY) 06/11/2021 (Street) BOSTON, MA02116 4. If Amendment, Date Original Filed (MM/DD/YY) 06/15/2021 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 ( 1 ) ( 2 ) 06/11/2021 02/04/2021 A 922,118 A $ 0 6,387,624 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 Options ( 3 ) $ 922,118 06/11/2021 02/04/2021 A 922,118 02/04/2022 06/11/2031 Common Stock 922,118 $ 10.36 922,118 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Gregoriou Vassilios C/O ADVENT TECHNOLOGIES HOLDINGS, INC. 200 CLARENDON STREET BOSTON, MA02116 X X Chairman and CEO Signatures /s/ Vassilios Gregoriou 06/15/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )This amended Form 4 is being filed only to report that the reporting holder is also a 10% holder. No changes to the originally filed Form 4 are otherwise being reported on this amended Form 4. The line item in Table I is included only to include this footnote in order to gain access to the SEC's filing system. ( 2 )Received pursuant to the Advent Technologies Holdings, Inc. 2021 Equity Incentive Plan, dated as of February 4, 2021. The options will vest 25% upon each anniversary of February 4, 2021, the vesting commencement date, until the fourth anniversary of the vesting commencement date. ( 3 )Received pursuant to the Advent Technologies Holdings, Inc. 2021 Equity Incentive Plan, dated as of February 4, 2021. The restricted stock units will vest 25% upon each anniversary of February 4, 2021, the vesting commencement date, until the fourth anniversary of the vesting commencement date.

Remarks: See Exhibit 24 - Power of Attorney

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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