Sec Form 4 Filing - Casdin Partners Master Fund, L.P. @ STANDARD BIOTOOLS INC. - 2022-04-04

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 Partners Master Fund, L.P. 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) 1350 AVENUE OF THE AMERICAS, SUITE 2600 3. Date of Earliest Transaction (MM/DD/YY) 04/04/2022 (Street) NEW YORK, NY10019 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

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 Series B-1 Convertible Preferred Stock ( 1 ) 04/04/2022 A 127,780 ( 1 ) ( 1 ) Common Stock 37,582,346( 1 ) ( 2 ) 127,780 D( 3 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Casdin Partners Master Fund, L.P. 1350 AVENUE OF THE AMERICAS, SUITE 2600 NEW YORK, NY10019 X X Casdin Capital, LLC 1350 AVENUE OF THE AMERICAS, SUITE 2600 NEW YORK, NY10019 X X Casdin Partners GP, LLC 1350 AVENUE OF THE AMERICAS, SUITE 2600 NEW YORK, NY10019 X X Casdin Private Growth Equity Fund II, L.P. 1350 AVENUE OF THE AMERICAS, SUITE 2600 NEW YORK, NY10019 X X Casdin Private Growth Equity Fund II GP, LLC 1350 AVENUE OF THE AMERICAS, SUITE 2600 NEW YORK, NY10019 X X Signatures Casdin Partners Master Fund, L.P., By: Casdin Partners GP, LLC, Its: General Partner, By: /s/ Eli Casdin, Its: Managing Member 04/06/2022 Signature of Reporting Person Date Casdin Capital, LLC, By: /s/ Eli Casdin, Its: Managing Member 04/06/2022 Signature of Reporting Person Date Casdin Partners GP, LLC, By: /s/ Eli Casdin, Its: Managing Member 04/06/2022 Signature of Reporting Person Date Casdin Private Growth Equity Fund II, L.P., By: Casdin Private Growth Equity Fund II GP, LLC, By: /s/ Eli Casdin, Its: Managing Member 04/06/2022 Signature of Reporting Person Date Casdin Private Growth Equity Fund II GP, LLC, By: /s/ Eli Casdin, Its: Managing Member 04/06/2022 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each share of the Issuer's Series B-1 Convertible Preferred Stock (the "Series B-1 Preferred Stock") is convertible at the option of the Reporting Person at any time into a number of shares of the Issuer's common stock, par value $0.001 per share, equal to the conversion rate, which is initially 294.1176, subject to certain anti-dilution adjustments and limitations on conversion pursuant to the Certificate of Designation for the Series B-1 Preferred Stock. ( 2 )On April 4, 2022, the Issuer issued the Series B-1 Preferred Stock (i) in exchange for aggregate cash consideration of $112.5 million, pursuant to the Series B-1 Convertible Preferred Stock Purchase Agreement, dated as of January 23, 2022, among the Issuer, Casdin Partners Master Fund, L.P. ("Casdin Master Fund") and Casdin Private Growth Equity Fund II, L.P. ("Casdin Private Growth Fund") and (ii) upon the conversion of $12.5 million aggregate principal amount of term loans, including accrued and unpaid interest, pursuant to the Series B-1 Loan Agreement, dated as of January 23, 2022, among the Issuer, Casdin Master Fund and Casdin Private Growth Fund. ( 3 )These shares are held by Casdin Master Fund and Casdin Private Growth Fund. Casdin Capital, LLC ("Casdin Capital") is the investment adviser to Casdin Master Fund and Casdin Private Growth Fund. Casdin Partners GP, LLC ("Casdin Partners GP") is the general partner of Casdin Master Fund and Casdin Private Growth Equity Fund II GP, LLC ("Casdin Private Growth GP") is the general partner of Casdin Private Growth Fund. Eli Casdin is the managing member of Casdin Capital, Casdin Partners GP and Casdin Private Growth GP. Each of Casdin Capital, Casdin Partners GP, Casdin Private Growth GP and Eli Casdin disclaims beneficial ownership of such securities except to the extent of their respective pecuniary interest therein, if any.

Remarks: Eli Casdin has been deputized to represent the Reporting Persons on the board of directors of the Issuer. By virtue of Mr. Casdin's representation, for purposes of Section 16 of the Securities Exchange Act of 1934 (the "Exchange Act"), each of the Reporting Persons may be deemed directors by deputization of the Issuer. Mr. Casdin files separate Section 16 reports disclosing securities of the Issuer that he may be deemed to beneficially own for Section 16 purposes.

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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