Casdin entities add LAB stake with open-market share purchases

Rhea-AI Filing Summary

Standard BioTools Inc. (LAB) reported insider open-market purchases of its common stock by Casdin-affiliated investment entities that are directors and 10% owners. On 11/13/2025, they bought 450,000 shares at a weighted average price of $1.2031 per share. On 11/14/2025, they bought another 250,000 shares at a weighted average price of $1.2392, and on 11/17/2025, they bought 225,000 shares at a weighted average price of $1.2248.

Following these transactions, one indirect position is shown as 62,975,000 shares, with additional direct and indirect holdings of 2,901,062, 13,939,637, and 2,744,219 shares reported for various Casdin-managed funds and Eli Casdin. The filing notes that prices are weighted averages over multiple trades within stated ranges and that the securities of several funds may be deemed beneficially owned by Casdin Capital entities and Eli Casdin.

SEC Form 4

FORM 4

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
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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 for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Casdin Partners Master Fund, L.P.

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

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)

3. Date of Earliest Transaction (Month/Day/Year)
11/13/2025

4. If Amendment, Date of 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

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	11/13/2025		P		450,000	A	$1.2031(1)	62,500,000	I	See footnote(4)
Common Stock, $0.001 par value per share	11/14/2025		P		250,000	A	$1.2392(2)	62,750,000	I	See footnote(4)
Common Stock, $0.001 par value per share	11/17/2025		P		225,000	A	$1.2248(3)	62,975,000	I	See footnote(4)
Common Stock, $0.001 par value per share								2,901,062	D(5)
Common Stock, $0.001 par value per share								13,939,637	I	See footnote(6)
Common Stock, $0.001 par value per share								2,744,219	I	See foonote(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 (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 Securities Underlying Derivative Security (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: 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

1. Name and Address of Reporting Person^*

Casdin Partners Master Fund, L.P.

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Casdin Capital, LLC

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Casdin Partners GP, LLC

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Casdin Private Growth Equity Fund II, L.P.

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Casdin Private Growth Equity Fund II GP, LLC

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS, SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Casdin Private Growth Equity Fund, L.P.

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

CASDIN PRIVATE GROWTH EQUITY FUND GP, LLC

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Casdin Eli

(Last) (First) (Middle)

1350 AVENUE OF THE AMERICAS

SUITE 2600

(Street)

NEW YORK NY 10019

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

X	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

Explanation of Responses:

1. The price reported in Column 4 is a weighted average price. These shares were bought in multiple transactions within the range of $1.1978 to $1.2098. The Reporting Persons undertake 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 price reported in Column 4 is a weighted average price. These shares were bought in multiple transactions within the range of $1.2364 to $1.2434. The Reporting Persons undertake 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.

3. The price reported in Column 4 is a weighted average price. These shares were bought in multiple transactions within the range of $1.2175 to $1.2299. The Reporting Persons undertake 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 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.

5. The securities are owned directly by Eli Casdin.

6. 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.

7. 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.

	Casdin Partners Master Fund, LP, By: Casdin Partners GP, LLC, its General Partner, By: /s/ Eli Casdin, Managing Member	11/17/2025
	Casdin Capital LLC, By: /s/ Eli Casdin, Managing Member	11/17/2025
	Casdin Partners GP LLC, By: /s/ Eli Casdin, Managing Member	11/17/2025
	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	11/17/2025
	Casdin Private Growth Equity Fund GP II, LLC, By: /s/ Eli Casdin, Managing Member	11/17/2025
	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	11/17/2025
	Casdin Private Growth Equity Fund GP, LLC, By: /s/ Eli Casdin, Managing Member	11/17/2025
	/s/ Eli Casdin, Eli Casdin	11/17/2025
	** Signature of Reporting Person	Date
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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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FAQ

What insider transactions were reported for STANDARD BIOTOOLS INC. (LAB)?

The filing reports that Casdin-affiliated entities purchased 450,000 LAB common shares on 11/13/2025, 250,000 shares on 11/14/2025, and 225,000 shares on 11/17/2025 in open-market transactions.

At what prices did the Casdin entities buy LAB shares?

The purchases were made at weighted average prices of $1.2031 per share on 11/13/2025, $1.2392 per share on 11/14/2025, and $1.2248 per share on 11/17/2025, each reflecting multiple trades within disclosed price ranges.

How many STANDARD BIOTOOLS (LAB) shares are shown as indirectly owned after the transactions?

After the reported transactions, one line item shows 62,975,000 LAB common shares held indirectly, with the nature of indirect beneficial ownership described in the footnotes for Casdin Partners Master Fund, L.P. and related entities.

What other LAB share holdings are reported for Eli Casdin and related funds?

The filing lists additional holdings of 2,901,062 LAB shares held directly by Eli Casdin, and indirect positions of 13,939,637 shares for Casdin Private Growth Equity Fund II, L.P. and 2,744,219 shares for Casdin Private Growth Equity Fund, L.P.

Who are the reporting persons in this Form 4 for STANDARD BIOTOOLS (LAB)?

The reporting persons include Casdin Partners Master Fund, L.P., various Casdin private growth equity funds and their general partners, Casdin Capital, LLC, and Eli Casdin, who is identified as a managing member of the relevant entities.

What is the relationship of the Casdin entities to STANDARD BIOTOOLS INC.?

The filing states that the reporting persons are directors and 10% owners, and that Eli Casdin has been deputized to represent the reporting persons on the board of directors of Standard BioTools Inc.

How are weighted average prices described in this LAB insider filing?

For each transaction date, the price in Column 4 is described as a weighted average price, with the shares bought in multiple transactions within specified price ranges, and the reporting persons commit to provide detailed trade-level prices upon request.