Sec Form 3 Filing - ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI @ Sema4 Holdings Corp. - 2021-07-22

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 ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI 2. Issuer Name and Ticker or Trading Symbol Sema4 Holdings Corp. [ SMFR] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 1 GUSTAVE L. LEVY PLACE, 3. Date of Earliest Transaction (MM/DD/YY) 07/22/2021 (Street) NEW YORK, NY10029 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ 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 88,355,473 D ( 1 )

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 Earn-out Shares ( 2 ) $ 0 ( 3 ) ( 4 ) Class A Common Stock 11,597,198 ( 5 ) D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI 1 GUSTAVE L. LEVY PLACE NEW YORK, NY10029 X MOUNT SINAI HEALTH SYSTEM, INC. 150 EAST 42ND STREET SUITE 2-B.17 NEW YORK, NY10017 X Signatures /s/ Stephen Harvey 10/07/2021 Signature of Reporting Person Date /s/ Stephen Harvey 10/07/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The securities reported herein are held directly by the Reporting Person. As its sole member, Mount Sinai Health System, Inc., a NY not-for-profit corporation ("MSHS"), may be deemed to beneficially own securities owned by the Reporting Person; however, MSHS does not have voting or investment power over such securities and disclaims beneficial interest therein except to the extent of its pecuniary interest, if any. ( 2 )Shares of Issuer's Class A common stock that may be issued upon the occurrence of certain triggering events pursuant to the earn-out provisions of that certain Agreement and Plan of Merger, dated February 9, 2021 (the "Merger Agreement"), by and among CM Life Sciences, Inc., S-IV Sub, Inc., and Mount Sinai Genomics, Inc. d/b/a Sema4 (the "Earn Out Shares"). ( 3 )See footnote 2. ( 4 )Not applicable. ( 5 )Maximum number of shares of Class A common stock of Issuer that may be issued to Reporting Person pursuant to the Merger Agreement as a result of the occurrence of certain triggering events set forth therein.

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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