Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 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 (Month/Day/Year) 09/03/2025 (Street) NEW YORK, NY 10019 4. If Amendment, Date Original Filed (Month/Day/Year) 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 (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 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, $0.001 par value per share 09/03/2025 P 250,000 A $1.2656(1) 60,525,000 I See footnote(2) Common Stock, $0.001 par value per share 09/04/2025 P 250,000 A $1.2774(3) 60,775,000 I See footnote(2) Common Stock, $0.001 par value per share 2,901,062 D(4) Common Stock, $0.001 par value per share 13,939,637 I See footnote(5) Common Stock, $0.001 par value per share 2,744,219 I See footnote(6)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

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 (Month/Day/Year)

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
Casdin Partners Master Fund, L.P. 1350 AVENUE OF THE AMERICAS SUITE 2600 NEW YORK, NY 10019	X	X
Casdin Capital, LLC 1350 AVENUE OF THE AMERICAS SUITE 2600 NEW YORK, NY 10019	X	X
Casdin Partners GP, LLC 1350 AVENUE OF THE AMERICAS SUITE 2600 NEW YORK, NY 10019	X	X
Casdin Private Growth Equity Fund II, L.P. 1350 AVENUE OF THE AMERICAS SUITE 2600 NEW YORK, NY 10019	X
Casdin Private Growth Equity Fund II GP, LLC 1350 AVENUE OF THE AMERICAS, SUITE 2600 NEW YORK, NY 10019	X
Casdin Private Growth Equity Fund, L.P. 1350 AVENUE OF THE AMERICAS SUITE 2600 NEW YORK, NY 10019	X
CASDIN PRIVATE GROWTH EQUITY FUND GP, LLC 1350 AVENUE OF THE AMERICAS SUITE 2600 NEW YORK, NY 10019	X
Casdin Eli 1350 AVENUE OF THE AMERICAS SUITE 2600 NEW YORK, NY 10019	X	X

Signatures

Casdin Partners Master Fund, LP, By: Casdin Partners GP, LLC, its General Partner, By: /s/ Eli Casdin, Managing Member		09/05/2025
**Signature of Reporting Person		Date
Casdin Capital LLC, By: /s/ Eli Casdin, Managing Member		09/05/2025
**Signature of Reporting Person		Date
Casdin Partners GP LLC, By: /s/ Eli Casdin, Managing Member		09/05/2025
**Signature of Reporting Person		Date
Casdin Private Growth Equity Fund II, L.P., By: Casdin Private Growth Equity Fund II GP, LLC, its General Partner, By: /s/ Eli Casdin, Managing Member		09/05/2025
**Signature of Reporting Person		Date
Casdin Private Growth Equity Fund GP II, LLC, By: /s/ Eli Casdin, Managing Member		09/05/2025
**Signature of Reporting Person		Date
Casdin Private Growth Equity Fund, L.P., By: Casdin Private Growth Equity Fund II GP, LLC, its General Partner, By: /s/ Eli Casdin, Managing Member		09/05/2025
**Signature of Reporting Person		Date
Casdin Private Growth Equity Fund GP, LLC, By: /s/ Eli Casdin, Managing Member		09/05/2025
**Signature of Reporting Person		Date
/s/ Eli Casdin, Eli Casdin		09/05/2025
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(1)	The price reported in Column 4 is a weighted average price. These shares were bought in multiple transactions within the range of $1.2414 to $1.2765. The Reporting Persons undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares bought at each separate price within the range set forth in this footnote.
(2)	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 Capital, LLC ("Casdin"), the investment adviser to the Master Fund, (ii) Casdin Partners GP, LLC (the "GP"), the general partner of the Master Fund, and (iii) Eli Casdin, the managing member of Casdin and the GP.
(3)	The price reported in Column 4 is a weighted average price. These shares were bought in multiple transactions within the range of $1.2621 to $1.2930. The Reporting Persons undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares bought at each separate price within the range set forth in this footnote.
(4)	The securities are owned directly by Eli Casdin.
(5)	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, the investment adviser to the Equity Fund II, and (ii) Eli Casdin, the managing member of Casdin.
(6)	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.
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. Each Reporting Person disclaims beneficial ownership in the securities reported on this Form 4 except to the extent of its pecuniary interest, if any, therein, and this report shall not be deemed to be an admission that such Reporting Person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.

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