Sec Form 3/A Filing - Squarer Ron @ ADC Therapeutics SA - 2024-01-02

FORM 3/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 Squarer Ron 2. Issuer Name and Ticker or Trading Symbol ADC Therapeutics SA [ ADCT] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 430 MOUNTAIN AVENUE, SUITE 404 3. Date of Earliest Transaction (MM/DD/YY) 01/02/2024 (Street) NEW PROVIDENCE, NJ07974 4. If Amendment, Date Original Filed (MM/DD/YY) 01/02/2024 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 Shares 35,806 ( 1 ) 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 (Right to Buy) $ 18.75 ( 2 ) 04/29/2030 Common Shares 966,519 D Stock Options (Right to Buy) $ 28.7 ( 3 ) 03/22/2031 Common Shares 27,412 D Stock Options (Right to Buy) $ 14 ( 4 ) 03/07/2032 Common Shares 29,836 D Stock Options (Right to Buy) $ 18.75 ( 5 ) 04/29/2030 Common Shares 159,026 I By grantor retained annuity trust

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Squarer Ron 430 MOUNTAIN AVENUE SUITE 404 NEW PROVIDENCE, NJ07974 X Signatures /s/ Ameet Mallik, as Attorney-in-Fact for Ron Squarer 06/05/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On January 2, 2024, a Form 3 was filed on behalf of the Reporting Person which inadvertently overstated the number of securities reported in Column 2 of Table I by 11,852 shares due to an administrative error. This Form 3 amendment is being filed to correct the aggregate number of shares beneficially owned by the Reporting Person as of the original transaction date and also applies to the number of shares reported as beneficially owned by the Reporting Person on any Forms 4 filed since January 2, 2024. ( 2 )On January 2, 2024, a Form 3 was filed on behalf of the Reporting Person which inadvertently underreported the number of securities reported in Column 3 of Table II by 468,977 shares due to an administrative error. This Form 3 amendment is being filed to correct the aggregate number of shares beneficially owned by the Reporting Person as of the original transaction date and also applies to the number of shares reported as beneficially owned by the Reporting Person on any Forms 4 filed since January 2, 2024. ( 3 )On January 2, 2024, a Form 3 was filed on behalf of the Reporting Person which inadvertently overstated the number of securities reported in Column 3 of Table II by 16,447 shares due to an administrative error. These options are fully vested and exercisable. This Form 3 amendment is being filed to correct the aggregate number of shares beneficially owned by the Reporting Person as of the original transaction date and also applies to the number of shares reported as beneficially owned by the Reporting Person on any Forms 4 filed since January 2, 2024. ( 4 )On January 2, 2024, a Form 3 was filed on behalf of the Reporting Person which inadvertently overstated the number of securities reported in Column 3 of Table II by 45,539 shares due to an administrative error. These options are fully vested and exercisable. This Form 3 amendment is being filed to correct the aggregate number of shares beneficially owned by the Reporting Person as of the original transaction date and also applies to the number of shares reported as beneficially owned by the Reporting Person on any Forms 4 filed since January 2, 2024. ( 5 )Due to an administrative error, the previous Form 3 filing inadvertently overstated the number of options contributed to a grantor annuity trust for the benefit of the Ron Squarer 2014 Irrevocable Life Insurance Trust by 309,951 options. The correct number of options contributed to the grantor annuity trust for the benefit of the Ron Squarer 2014 Irrevocable Life Insurance Trust is reflected in this filing.

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).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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