Sec Form 3 Filing - Martin Ryan @ Fathom Digital Manufacturing Corp - 2021-12-23

FORM 3 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 Martin Ryan 2. Issuer Name and Ticker or Trading Symbol Fathom Digital Manufacturing Corp [ FATH] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Executive Officer (Last) (First) (Middle) C/O FATHOM DIGITAL MANUFACTURING CORP., 1050 WALNUT RIDGE DRIVE 3. Date of Earliest Transaction (MM/DD/YY) 12/23/2021 (Street) HARTLAND, WI53029 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 Class A Common Stock( 1 ) 232,760 D Class A Common Stock( 2 )( 3 ) 1,629,317 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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Martin Ryan C/O FATHOM DIGITAL MANUFACTURING CORP. 1050 WALNUT RIDGE DRIVE HARTLAND, WI53029 X Chief Executive Officer Signatures /s/Ryan Martin, by James R. Brown as Attorney-in-Fact 01/03/2022 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On December 23, 2021 (the "Effective Time"), the Issuer, formerly known as Altimar Acquisition Corp. II, acquired Fathom Holdco, LLC ("Fathom") pursuant to a Business Combination Agreement by and among the Issuer, Fathom and certain other parties thereto (the "Business Combination Agreement"). These shares of Class A Common Stock were issued to the Reporting Person pursuant to the Business Combination Agreement in exchange for vested shares of phantom equity in Fathom. ( 2 )Represents shares of Class A Common Stock underlying Restricted Stock Units ("RSUs") issued under the Fathom Digital Manufacturing Corporation 2021 Omnibus Incentive Plan, as amended and/or restated from time to time. Each RSU represents the contingent right to receive one share of the Issuer's Class A Common Stock. These RSUs were issued to the Reporting Person pursuant to the Business Combination Agreement in exchange for unvested shares of phantom equity in Fathom. 232,759 of these RSUs are time-vesting, with half vesting on January 7, 2022 and half vesting on January 7, 2023, subject to continued service through the applicable vesting date. The remaining 1,396,558 RSUs are subject to performance-based vesting conditions based upon the sell-down percentage of (a) CORE Industrial Partners Fund I, LP, CORE Industrial Partners Fund I Parallel, LP, CORE Fund I Holdings-2, LP and CORE Fund I Holdings-5 LP (collectively, the "CORE Investors"), and ( 3 )(Continued from footnote 2)(b) with respect to the CORE Investors, any person directly controlled by, directly controlling or under direct common control with the CORE Investors (collectively, the "CORE Affiliates") as follows: (1) 25% of the performance-based RSUs will vest if the CORE Investors and the CORE Affiliates collectively sell-down an investor cumulative sale percentage equal or greater than 60%; (2) 25% of the performance-based RSUs will vest if the CORE Investors and the CORE Affiliates collectively sell-down an investor cumulative sale percentage equal or greater than 80%; and (3) 50% of the performance-based RSUs will vest if the CORE Investors and the CORE Affiliates collectively sell-down an investor cumulative sale percentage equal or greater than 95%.

Remarks: Exhibit 24 - Power of Attorney

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