Sec Form 4 Filing - Casdin Eli @ STANDARD BIOTOOLS INC. - 2024-06-28

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 Casdin Eli 2. Issuer Name and Ticker or Trading Symbol STANDARD BIOTOOLS INC. [ LAB] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O STANDARD BIOTOOLS INC., 2 TOWER PLACE, STE 2000 3. Date of Earliest Transaction (MM/DD/YY) 06/28/2024 (Street) SOUTH SAN FRANCISCO, CA94080 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 06/28/2024 A 43,128 ( 1 ) A $ 0 2,750,744 ( 2 ) D Common Stock 13,939,637 I Casdin Private Growth Equity Fund II, L.P. ( 3 ) Common Stock 2,744,219 I By Casdin Private Growth Equity Fund, L.P. ( 4 ) Common Stock 18,870 I See footnote ( 5 ) Common Stock 46,730,821 I Casdin Partners Master Fund, L.P ( 6 ) Common Stock 545,000 I Casdin Amplify Fund, LP ( 7 )

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) $ 1.77 06/28/2024 A 72,213 ( 8 ) 06/28/2034 Common Stock 72,213 $ 0 72,213 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Casdin Eli C/O STANDARD BIOTOOLS INC. 2 TOWER PLACE, STE 2000 SOUTH SAN FRANCISCO, CA94080 X X Signatures /s/ Eli Casdin by Agnieszka Gallagher, Attorney-in-Fact 07/02/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents Restricted Stock Units ("RSUs") that vest in full on the earlier to occur of June 28, 2025 and one day prior to the date of the Company's next annual meeting of stockholders, subject to the Reporting Person's continued service through the applicable vesting date. Each RSU represents the right to receive one share of common stock upon vesting. ( 2 )Includes 2,604,060 shares of common stock received in a pro rata distribution for no consideration by C-LSH II LLC in accordance with the exemptions afforded by Rule 16a-9 of the Securities Exchange Act of 1934, as amended. ( 3 )The securities are owned directly by Casdin Private Growth Equity Fund II, L.P. (the "Equity Fund II") and may be deemed to be indirectly beneficially owned by (i) Casdin Capital, LLC ("Casdin"), the investment adviser to the Equity Fund II, and (ii) Eli Casdin, the managing member of Casdin. ( 4 )The securities are owned directly by Casdin Private Growth Equity Fund, L.P. (the "Equity Fund") and may be deemed to be indirectly beneficially owned by (i) Casdin, the investment adviser to the Equity Fund, and (ii) Eli Casdin, the managing member of Casdin. ( 5 )The securities are indirectly owned by Eli Casdin who has voting and investment discretion with respect to the securities. ( 6 )The securities are owned directly by Casdin Partners Master Fund, L.P. (the "Master Fund") and may be deemed to be indirectly beneficially owned by (i) Casdin, the investment adviser to the Master Fund, (ii) Casdin Partners GP, LLC, the general partner of the Master Fund (the "GP"), and (iii) Eli Casdin, the managing member of Casdin and the GP. ( 7 )The securities are owned directly by Casdin Amplify Fund, LP ("Amplify") and are deemed to be indirectly beneficially owned by (i) Casdin, the investment adviser to Amplify, (ii) the GP, the general partner of Amplify, and (iii) Eli Casdin, the managing member of Casdin and the GP. ( 8 )The Option becomes exercisable in twelve equal monthly installments beginning on July 28, 2024, subject to the Reporting Person's continued service through the applicable vesting date.

Remarks: The Reporting Person disclaims beneficial ownership in the securities reported on this Form 4 except to the extent of his pecuniary interest, if any, therein, and this report shall not be deemed to be an admission that the Reporting Person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.

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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